diff --git a/src/common/pico_base/include/pico/types.h b/src/common/pico_base/include/pico/types.h
index 37a4c30..40856bd 100644
--- a/src/common/pico_base/include/pico/types.h
+++ b/src/common/pico_base/include/pico/types.h
@@ -76,4 +76,6 @@ typedef struct {
     int8_t sec;      ///< 0..59
 } datetime_t;
 
+#define bool_to_bit(x) ((uint)!!(x))
+
 #endif
diff --git a/src/common/pico_sync/critical_section.c b/src/common/pico_sync/critical_section.c
index 5f47090..893afb6 100644
--- a/src/common/pico_sync/critical_section.c
+++ b/src/common/pico_sync/critical_section.c
@@ -11,7 +11,7 @@ static_assert(sizeof(critical_section_t) == 8, "");
 #endif
 
 void critical_section_init(critical_section_t *critsec) {
-    critical_section_init_with_lock_num(critsec, spin_lock_claim_unused(true));
+    critical_section_init_with_lock_num(critsec, (uint)spin_lock_claim_unused(true));
 }
 
 void critical_section_init_with_lock_num(critical_section_t *critsec, uint lock_num) {
diff --git a/src/common/pico_sync/mutex.c b/src/common/pico_sync/mutex.c
index 531666f..4b4bb27 100644
--- a/src/common/pico_sync/mutex.c
+++ b/src/common/pico_sync/mutex.c
@@ -23,7 +23,7 @@ void __time_critical_func(mutex_enter_blocking)(mutex_t *mtx) {
     do {
         uint32_t save = spin_lock_blocking(mtx->core.spin_lock);
         if (mtx->owner < 0) {
-            mtx->owner = get_core_num();
+            mtx->owner = (int8_t)get_core_num();
             block = false;
         }
         spin_unlock(mtx->core.spin_lock, save);
@@ -37,10 +37,10 @@ bool __time_critical_func(mutex_try_enter)(mutex_t *mtx, uint32_t *owner_out) {
     bool entered;
     uint32_t save = spin_lock_blocking(mtx->core.spin_lock);
     if (mtx->owner < 0) {
-        mtx->owner = get_core_num();
+        mtx->owner = (int8_t)get_core_num();
         entered = true;
     } else {
-        if (owner_out) *owner_out = mtx->owner;
+        if (owner_out) *owner_out = (uint32_t) mtx->owner;
         entered = false;
     }
     spin_unlock(mtx->core.spin_lock, save);
@@ -57,7 +57,7 @@ bool __time_critical_func(mutex_enter_block_until)(mutex_t *mtx, absolute_time_t
     do {
         uint32_t save = spin_lock_blocking(mtx->core.spin_lock);
         if (mtx->owner < 0) {
-            mtx->owner = get_core_num();
+            mtx->owner = (int8_t)get_core_num();
             block = false;
         }
         spin_unlock(mtx->core.spin_lock, save);
diff --git a/src/common/pico_sync/sem.c b/src/common/pico_sync/sem.c
index 4ed7285..195cd9a 100644
--- a/src/common/pico_sync/sem.c
+++ b/src/common/pico_sync/sem.c
@@ -63,7 +63,7 @@ bool __time_critical_func(sem_release)(semaphore_t *sem) {
     uint32_t save = spin_lock_blocking(sem->core.spin_lock);
     int32_t count = sem->permits;
     if (count < sem->max_permits) {
-        sem->permits = count + 1;
+        sem->permits = (int16_t)(count + 1);
         __sev();
         rc = true;
     } else {
diff --git a/src/common/pico_time/include/pico/time.h b/src/common/pico_time/include/pico/time.h
index bac1fb3..bacddf3 100644
--- a/src/common/pico_time/include/pico/time.h
+++ b/src/common/pico_time/include/pico/time.h
@@ -152,7 +152,7 @@ static inline absolute_time_t make_timeout_time_ms(uint32_t ms) {
  * in case of overflow)
  */
 static inline int64_t absolute_time_diff_us(absolute_time_t from, absolute_time_t to) {
-    return to_us_since_boot(to) - to_us_since_boot(from);
+    return (int64_t)(to_us_since_boot(to) - to_us_since_boot(from));
 }
 
 /*! \brief The timestamp representing the end of time; no timestamp is after this
diff --git a/src/common/pico_time/time.c b/src/common/pico_time/time.c
index 043f6e7..0cc7efd 100644
--- a/src/common/pico_time/time.c
+++ b/src/common/pico_time/time.c
@@ -71,12 +71,12 @@ bool timer_pool_entry_comparator(void *user_data, pheap_node_id_t a, pheap_node_
 }
 
 static inline alarm_id_t make_public_id(uint8_t id_high, pheap_node_id_t id) {
-    return ((uint)id_high << 8u * sizeof(id)) | id;
+    return (alarm_id_t)(((uint)id_high << 8u * sizeof(id)) | id);
 }
 
-static alarm_id_t add_alarm_under_lock(alarm_pool_t *pool, absolute_time_t time, alarm_callback_t callback,
-                                       void *user_data, alarm_id_t reuse_id, bool create_if_past, bool *missed) {
-    alarm_id_t id;
+static pheap_node_id_t add_alarm_under_lock(alarm_pool_t *pool, absolute_time_t time, alarm_callback_t callback,
+                                       void *user_data, pheap_node_id_t reuse_id, bool create_if_past, bool *missed) {
+    pheap_node_id_t id;
     if (reuse_id) {
         assert(!ph_contains(pool->heap, reuse_id));
         id = reuse_id;
@@ -137,10 +137,10 @@ static void alarm_pool_alarm_callback(uint alarm_num) {
             // todo think more about whether we want to keep calling
             if (repeat < 0 && pool->alarm_in_progress) {
                 assert(pool->alarm_in_progress == make_public_id(id_high, next_id));
-                add_alarm_under_lock(pool, delayed_by_us(target, -repeat), callback, user_data, next_id, true, NULL);
+                add_alarm_under_lock(pool, delayed_by_us(target, (uint64_t)-repeat), callback, user_data, next_id, true, NULL);
             } else if (repeat > 0 && pool->alarm_in_progress) {
                 assert(pool->alarm_in_progress == make_public_id(id_high, next_id));
-                add_alarm_under_lock(pool, delayed_by_us(get_absolute_time(), repeat), callback, user_data, next_id,
+                add_alarm_under_lock(pool, delayed_by_us(get_absolute_time(), (uint64_t)repeat), callback, user_data, next_id,
                                      true, NULL);
             } else {
                 // need to return the id to the heap
@@ -164,7 +164,7 @@ alarm_pool_t *alarm_pool_create(uint hardware_alarm_num, uint max_timers) {
     pool->heap = ph_create(max_timers, timer_pool_entry_comparator, pool);
     pool->entries = (alarm_pool_entry_t *)calloc(max_timers, sizeof(alarm_pool_entry_t));
     pool->entry_ids_high = (uint8_t *)calloc(max_timers, sizeof(uint8_t));
-    pool->hardware_alarm_num = hardware_alarm_num;
+    pool->hardware_alarm_num = (uint8_t)hardware_alarm_num;
     pools[hardware_alarm_num] = pool;
     return pool;
 }
@@ -185,7 +185,7 @@ alarm_id_t alarm_pool_add_alarm_at(alarm_pool_t *pool, absolute_time_t time, ala
                                    void *user_data, bool fire_if_past) {
     bool missed = false;
 
-    uint public_id;
+    alarm_id_t public_id;
     do {
         uint8_t id_high = 0;
         uint32_t save = spin_lock_blocking(pool->lock);
@@ -205,9 +205,9 @@ alarm_id_t alarm_pool_add_alarm_at(alarm_pool_t *pool, absolute_time_t time, ala
                 public_id = 0;
                 break;
             } else if (repeat < 0) {
-                time = delayed_by_us(time, -repeat);
+                time = delayed_by_us(time, (uint64_t)-repeat);
             } else {
-                time = delayed_by_us(get_absolute_time(), repeat);
+                time = delayed_by_us(get_absolute_time(), (uint64_t)repeat);
             }
         } else {
             break;
@@ -270,7 +270,8 @@ bool alarm_pool_add_repeating_timer_us(alarm_pool_t *pool, int64_t delay_us, rep
     out->callback = callback;
     out->delay_us = delay_us;
     out->user_data = user_data;
-    out->alarm_id = alarm_pool_add_alarm_at(pool, make_timeout_time_us(delay_us >= 0 ? delay_us : -delay_us), repeating_timer_callback, out, true);
+    out->alarm_id = alarm_pool_add_alarm_at(pool, make_timeout_time_us((uint64_t)(delay_us >= 0 ? delay_us : -delay_us)),
+                                            repeating_timer_callback, out, true);
     return out->alarm_id > 0;
 }
 
diff --git a/src/common/pico_util/include/pico/util/queue.h b/src/common/pico_util/include/pico/util/queue.h
index d65548e..8281d8b 100644
--- a/src/common/pico_util/include/pico/util/queue.h
+++ b/src/common/pico_util/include/pico/util/queue.h
@@ -71,7 +71,7 @@ static inline uint queue_get_level_unsafe(queue_t *q) {
     if (rc < 0) {
         rc += + q->element_count + 1;
     }
-    return rc;
+    return (uint)rc;
 }
 
 /*! \brief Check of level of the specified queue.
diff --git a/src/common/pico_util/pheap.c b/src/common/pico_util/pheap.c
index 8e9c686..6ddc0cb 100644
--- a/src/common/pico_util/pheap.c
+++ b/src/common/pico_util/pheap.c
@@ -11,7 +11,7 @@
 pheap_t *ph_create(uint max_nodes, pheap_comparator comparator, void *user_data) {
     invalid_params_if(PHEAP, !max_nodes || max_nodes >= (1u << sizeof(pheap_node_id_t)));
     pheap_t *heap = calloc(1, sizeof(pheap_t));
-    heap->max_nodes = max_nodes;
+    heap->max_nodes = (pheap_node_id_t) max_nodes;
     heap->comparator = comparator;
     heap->nodes = calloc(max_nodes, sizeof(pheap_node_t));
     heap->user_data = user_data;
@@ -23,8 +23,8 @@ void ph_clear(pheap_t *heap) {
     heap->root_id = 0;
     heap->free_head_id = 1;
     heap->free_tail_id = heap->max_nodes;
-    for(uint i = 1; i < heap->max_nodes; i++) {
-        ph_get_node(heap, i)->sibling = i + 1;
+    for(pheap_node_id_t i = 1; i < heap->max_nodes; i++) {
+        ph_get_node(heap, i)->sibling = (pheap_node_id_t)(i + 1);
     }
     ph_get_node(heap, heap->max_nodes)->sibling = 0;
 }
diff --git a/src/common/pico_util/queue.c b/src/common/pico_util/queue.c
index 785e7f0..4b1c27e 100644
--- a/src/common/pico_util/queue.c
+++ b/src/common/pico_util/queue.c
@@ -11,8 +11,8 @@
 void queue_init_with_spinlock(queue_t *q, uint element_size, uint element_count, uint spinlock_num) {
     q->lock = spin_lock_instance(spinlock_num);
     q->data = (uint8_t *)calloc(element_count + 1, element_size);
-    q->element_count = element_count;
-    q->element_size = element_size;
+    q->element_count = (uint16_t)element_count;
+    q->element_size = (uint16_t)element_size;
     q->wptr = 0;
     q->rptr = 0;
 }
diff --git a/src/host/pico_platform/include/hardware/platform_defs.h b/src/host/pico_platform/include/hardware/platform_defs.h
index 1ca575e..c1451be 100644
--- a/src/host/pico_platform/include/hardware/platform_defs.h
+++ b/src/host/pico_platform/include/hardware/platform_defs.h
@@ -21,4 +21,8 @@
 
 #define NUM_SPIN_LOCKS 32u
 
+#ifndef _U
+#define _U(x) x ## u
+#endif
+
 #endif
diff --git a/src/rp2040/hardware_regs/include/hardware/platform_defs.h b/src/rp2040/hardware_regs/include/hardware/platform_defs.h
index 51c0272..9d503fe 100644
--- a/src/rp2040/hardware_regs/include/hardware/platform_defs.h
+++ b/src/rp2040/hardware_regs/include/hardware/platform_defs.h
@@ -40,6 +40,14 @@
 #define PICO_NO_RAM_VECTOR_TABLE 0
 #endif
 
+#ifndef _U
+#ifdef __ASSEMBLER__
+#define _U(x) x
+#else
+#define _U(x) x ## u
+#endif
+#endif
+
 #ifndef PICO_FLASH_SIZE_BYTES
 #define PICO_FLASH_SIZE_BYTES (2 * 1024 * 1024)
 #endif
diff --git a/src/rp2_common/hardware_adc/include/hardware/adc.h b/src/rp2_common/hardware_adc/include/hardware/adc.h
index 13d7c41..1e1864a 100644
--- a/src/rp2_common/hardware_adc/include/hardware/adc.h
+++ b/src/rp2_common/hardware_adc/include/hardware/adc.h
@@ -127,7 +127,7 @@ static inline uint16_t adc_read(void) {
     while (!(adc_hw->cs & ADC_CS_READY_BITS))
         tight_loop_contents();
 
-    return adc_hw->result;
+    return (uint16_t) adc_hw->result;
 }
 
 /*! \brief Enable or disable free-running sampling mode
@@ -166,13 +166,13 @@ static inline void adc_set_clkdiv(float clkdiv) {
  * \param err_in_fifo If enabled, bit 15 of the FIFO contains error flag for each sample
  * \param byte_shift Shift FIFO contents to be one byte in size (for byte DMA) - enables DMA to byte buffers.
  */
-static inline void adc_fifo_setup(bool en, bool dreq_en, uint16_t dreq_thresh, bool err_in_fifo, bool byte_shift) {
+ static inline void adc_fifo_setup(bool en, bool dreq_en, uint16_t dreq_thresh, bool err_in_fifo, bool byte_shift) {
     hw_write_masked(&adc_hw->fcs,
-                   (!!en << ADC_FCS_EN_LSB) |
-                   (!!dreq_en << ADC_FCS_DREQ_EN_LSB) |
-                   (dreq_thresh << ADC_FCS_THRESH_LSB) |
-                   (!!err_in_fifo << ADC_FCS_ERR_LSB) |
-                   (!!byte_shift << ADC_FCS_SHIFT_LSB),
+                   (bool_to_bit(en) << ADC_FCS_EN_LSB) |
+                   (bool_to_bit(dreq_en) << ADC_FCS_DREQ_EN_LSB) |
+                   (((uint)dreq_thresh) << ADC_FCS_THRESH_LSB) |
+                   (bool_to_bit(err_in_fifo) << ADC_FCS_ERR_LSB) |
+                   (bool_to_bit(byte_shift) << ADC_FCS_SHIFT_LSB),
                    ADC_FCS_EN_BITS |
                    ADC_FCS_DREQ_EN_BITS |
                    ADC_FCS_THRESH_BITS |
@@ -205,7 +205,7 @@ static inline uint8_t adc_fifo_get_level(void) {
  * Pops the latest result from the ADC FIFO.
  */
 static inline uint16_t adc_fifo_get(void) {
-    return adc_hw->fifo;
+    return (uint16_t)adc_hw->fifo;
 }
 
 /*! \brief Wait for the ADC FIFO to have data.
@@ -216,7 +216,7 @@ static inline uint16_t adc_fifo_get(void) {
 static inline uint16_t adc_fifo_get_blocking(void) {
     while (adc_fifo_is_empty())
         tight_loop_contents();
-    return adc_hw->fifo;
+    return (uint16_t)adc_hw->fifo;
 }
 
 /*! \brief Drain the ADC FIFO
diff --git a/src/rp2_common/hardware_claim/claim.c b/src/rp2_common/hardware_claim/claim.c
index 2c5c8ed..96f341e 100644
--- a/src/rp2_common/hardware_claim/claim.c
+++ b/src/rp2_common/hardware_claim/claim.c
@@ -20,7 +20,7 @@ bool hw_is_claimed(uint8_t *bits, uint bit_index) {
     if (bits[bit_index >> 3u] & (1u << (bit_index & 7u))) {
         rc = false;
     } else {
-        bits[bit_index >> 3u] |= (1u << (bit_index & 7u));
+        bits[bit_index >> 3u] |= (uint8_t)(1u << (bit_index & 7u));
         rc = true;
     }
     hw_claim_unlock(save);
@@ -32,7 +32,7 @@ void hw_claim_or_assert(uint8_t *bits, uint bit_index, const char *message) {
     if (bits[bit_index >> 3u] & (1u << (bit_index & 7u))) {
         panic(message, bit_index);
     } else {
-        bits[bit_index >> 3u] |= (1u << (bit_index & 7u));
+        bits[bit_index >> 3u] |= (uint8_t)(1u << (bit_index & 7u));
     }
     hw_claim_unlock(save);
 }
@@ -43,8 +43,8 @@ int hw_claim_unused_from_range(uint8_t *bits, bool required, uint bit_lsb, uint
     int found_bit = -1;
     for(uint bit=bit_lsb; bit <= bit_msb; bit++) {
         if (!(bits[bit >> 3u] & (1u << (bit & 7u)))) {
-            bits[bit >> 3u] |= (1u << (bit & 7u));
-            found_bit = bit;
+            bits[bit >> 3u] |= (uint8_t)(1u << (bit & 7u));
+            found_bit = (int)bit;
             break;
         }
     }
@@ -58,7 +58,7 @@ int hw_claim_unused_from_range(uint8_t *bits, bool required, uint bit_lsb, uint
 void hw_claim_clear(uint8_t *bits, uint bit_index) {
     uint32_t save = hw_claim_lock();
     assert(bits[bit_index >> 3u] & (1u << (bit_index & 7u)));
-    bits[bit_index >> 3u] &= ~(1u << (bit_index & 7u));
+    bits[bit_index >> 3u] &= (uint8_t) ~(1u << (bit_index & 7u));
     hw_claim_unlock(save);
 }
 
diff --git a/src/rp2_common/hardware_divider/include/hardware/divider.h b/src/rp2_common/hardware_divider/include/hardware/divider.h
index 5693e07..0be2ef8 100644
--- a/src/rp2_common/hardware_divider/include/hardware/divider.h
+++ b/src/rp2_common/hardware_divider/include/hardware/divider.h
@@ -53,8 +53,8 @@ typedef uint64_t divmod_result_t;
  */
 static inline void hw_divider_divmod_s32_start(int32_t a, int32_t b) {
     check_hw_layout( sio_hw_t, div_sdividend, SIO_DIV_SDIVIDEND_OFFSET);
-    sio_hw->div_sdividend = a;
-    sio_hw->div_sdivisor = b;
+    sio_hw->div_sdividend = (uint32_t)a;
+    sio_hw->div_sdivisor = (uint32_t)b;
 }
 
 /*! \brief Start an unsigned asynchronous divide
@@ -142,7 +142,7 @@ static inline uint32_t hw_divider_u32_quotient_wait(void) {
  */
 static inline int32_t hw_divider_s32_quotient_wait(void) {
     hw_divider_wait_ready();
-    return sio_hw->div_quotient;
+    return (int32_t)sio_hw->div_quotient;
 }
 
 /*! \brief Return result of last asynchronous HW divide, unsigned remainder only
@@ -154,7 +154,7 @@ static inline int32_t hw_divider_s32_quotient_wait(void) {
  */
 static inline uint32_t hw_divider_u32_remainder_wait(void) {
     hw_divider_wait_ready();
-    int32_t rc = sio_hw->div_remainder;
+    uint32_t rc = sio_hw->div_remainder;
     sio_hw->div_quotient; // must read quotient to cooperate with other SDK code
     return rc;
 }
@@ -168,7 +168,7 @@ static inline uint32_t hw_divider_u32_remainder_wait(void) {
  */
 static inline int32_t hw_divider_s32_remainder_wait(void) {
     hw_divider_wait_ready();
-    int32_t rc = sio_hw->div_remainder;
+    int32_t rc = (int32_t)sio_hw->div_remainder;
     sio_hw->div_quotient; // must read quotient to cooperate with other SDK code
     return rc;
 }
@@ -334,7 +334,7 @@ static inline uint32_t hw_divider_u32_quotient_inlined(uint32_t a, uint32_t b) {
 static inline uint32_t hw_divider_u32_remainder_inlined(uint32_t a, uint32_t b) {
     hw_divider_divmod_u32_start(a, b);
     hw_divider_pause();
-    int32_t rc = sio_hw->div_remainder;
+    uint32_t rc = sio_hw->div_remainder;
     sio_hw->div_quotient; // must read quotient to cooperate with other SDK code
     return rc;
 }
@@ -351,7 +351,7 @@ static inline uint32_t hw_divider_u32_remainder_inlined(uint32_t a, uint32_t b)
 static inline int32_t hw_divider_s32_quotient_inlined(int32_t a, int32_t b) {
     hw_divider_divmod_s32_start(a, b);
     hw_divider_pause();
-    return sio_hw->div_quotient;
+    return (int32_t)sio_hw->div_quotient;
 }
 
 /*! \brief Do a hardware signed HW divide, wait for result, return remainder
@@ -366,7 +366,7 @@ static inline int32_t hw_divider_s32_quotient_inlined(int32_t a, int32_t b) {
 static inline int32_t hw_divider_s32_remainder_inlined(int32_t a, int32_t b) {
     hw_divider_divmod_s32_start(a, b);
     hw_divider_pause();
-    int32_t rc = sio_hw->div_remainder;
+    int32_t rc = (int32_t)sio_hw->div_remainder;
     sio_hw->div_quotient; // must read quotient to cooperate with other SDK code
     return rc;
 }
diff --git a/src/rp2_common/hardware_dma/include/hardware/dma.h b/src/rp2_common/hardware_dma/include/hardware/dma.h
index dfb2de5..7c04728 100644
--- a/src/rp2_common/hardware_dma/include/hardware/dma.h
+++ b/src/rp2_common/hardware_dma/include/hardware/dma.h
@@ -186,7 +186,7 @@ static inline void channel_config_set_chain_to(dma_channel_config *c, uint chain
  */
 static inline void channel_config_set_transfer_data_size(dma_channel_config *c, enum dma_channel_transfer_size size) {
     assert(size == DMA_SIZE_8 || size == DMA_SIZE_16 || size == DMA_SIZE_32);
-    c->ctrl = (c->ctrl & ~DMA_CH0_CTRL_TRIG_DATA_SIZE_BITS) | (size << DMA_CH0_CTRL_TRIG_DATA_SIZE_LSB);
+    c->ctrl = (c->ctrl & ~DMA_CH0_CTRL_TRIG_DATA_SIZE_BITS) | (((uint)size) << DMA_CH0_CTRL_TRIG_DATA_SIZE_LSB);
 }
 
 /*! \brief  Set address wrapping parameters
diff --git a/src/rp2_common/hardware_flash/flash.c b/src/rp2_common/hardware_flash/flash.c
index c4cf830..c397fbb 100644
--- a/src/rp2_common/hardware_flash/flash.c
+++ b/src/rp2_common/hardware_flash/flash.c
@@ -149,7 +149,7 @@ static void __no_inline_not_in_flash_func(flash_do_cmd)(const uint8_t *txbuf, ui
             --tx_remaining;
         }
         if (can_get && rx_remaining) {
-            *rxbuf++ = ssi_hw->dr0;
+            *rxbuf++ = (uint8_t)ssi_hw->dr0;
             --rx_remaining;
         }
     }
diff --git a/src/rp2_common/hardware_gpio/gpio.c b/src/rp2_common/hardware_gpio/gpio.c
index 34be86c..b6335d0 100644
--- a/src/rp2_common/hardware_gpio/gpio.c
+++ b/src/rp2_common/hardware_gpio/gpio.c
@@ -50,7 +50,7 @@ void gpio_set_pulls(uint gpio, bool up, bool down) {
     invalid_params_if(GPIO, gpio >= NUM_BANK0_GPIOS);
     hw_write_masked(
             &padsbank0_hw->io[gpio],
-            (!!up << PADS_BANK0_GPIO0_PUE_LSB) | (!!down << PADS_BANK0_GPIO0_PDE_LSB),
+            (bool_to_bit(up) << PADS_BANK0_GPIO0_PUE_LSB) | (bool_to_bit(down) << PADS_BANK0_GPIO0_PDE_LSB),
             PADS_BANK0_GPIO0_PUE_BITS | PADS_BANK0_GPIO0_PDE_BITS
     );
 }
diff --git a/src/rp2_common/hardware_i2c/i2c.c b/src/rp2_common/hardware_i2c/i2c.c
index cc4212a..bcd9054 100644
--- a/src/rp2_common/hardware_i2c/i2c.c
+++ b/src/rp2_common/hardware_i2c/i2c.c
@@ -115,6 +115,7 @@ static int i2c_write_blocking_internal(i2c_inst_t *i2c, uint8_t addr, const uint
     // Synopsys hw accepts start/stop flags alongside data items in the same
     // FIFO word, so no 0 byte transfers.
     invalid_params_if(I2C, len == 0);
+    invalid_params_if(I2C, ((int)len) < 0);
 
     i2c->hw->enable = 0;
     i2c->hw->tar = addr;
@@ -124,15 +125,16 @@ static int i2c_write_blocking_internal(i2c_inst_t *i2c, uint8_t addr, const uint
     bool timeout = false;
 
     uint32_t abort_reason;
-    size_t byte_ctr;
+    int byte_ctr;
 
-    for (byte_ctr = 0; byte_ctr < len; ++byte_ctr) {
+    int ilen = (int)len;
+    for (byte_ctr = 0; byte_ctr < ilen; ++byte_ctr) {
         bool first = byte_ctr == 0;
-        bool last = byte_ctr == len - 1;
+        bool last = byte_ctr == ilen - 1;
 
         i2c->hw->data_cmd =
-                !!(first && i2c->restart_on_next) << I2C_IC_DATA_CMD_RESTART_LSB |
-                !!(last && !nostop) << I2C_IC_DATA_CMD_STOP_LSB |
+                bool_to_bit(first && i2c->restart_on_next) << I2C_IC_DATA_CMD_RESTART_LSB |
+                bool_to_bit(last && !nostop) << I2C_IC_DATA_CMD_STOP_LSB |
                 *src++;
 
         do {
@@ -203,6 +205,7 @@ static int i2c_read_blocking_internal(i2c_inst_t *i2c, uint8_t addr, uint8_t *ds
     invalid_params_if(I2C, addr >= 0x80); // 7-bit addresses
     invalid_params_if(I2C, i2c_reserved_addr(addr));
     invalid_params_if(I2C, len == 0);
+    invalid_params_if(I2C, ((int)len) < 0);
 
     i2c->hw->enable = 0;
     i2c->hw->tar = addr;
@@ -211,17 +214,17 @@ static int i2c_read_blocking_internal(i2c_inst_t *i2c, uint8_t addr, uint8_t *ds
     bool abort = false;
     bool timeout = false;
     uint32_t abort_reason;
-    size_t byte_ctr;
-
-    for (byte_ctr = 0; byte_ctr < len; ++byte_ctr) {
+    int byte_ctr;
+    int ilen = (int)len;
+    for (byte_ctr = 0; byte_ctr < ilen; ++byte_ctr) {
         bool first = byte_ctr == 0;
-        bool last = byte_ctr == len - 1;
+        bool last = byte_ctr == ilen - 1;
         while (!i2c_get_write_available(i2c))
             tight_loop_contents();
 
         i2c->hw->data_cmd =
-                !!(first && i2c->restart_on_next) << I2C_IC_DATA_CMD_RESTART_LSB |
-                !!(last && !nostop) << I2C_IC_DATA_CMD_STOP_LSB |
+                bool_to_bit(first && i2c->restart_on_next) << I2C_IC_DATA_CMD_RESTART_LSB |
+                bool_to_bit(last && !nostop) << I2C_IC_DATA_CMD_STOP_LSB |
                 I2C_IC_DATA_CMD_CMD_BITS; // -> 1 for read
 
         do {
@@ -236,7 +239,7 @@ static int i2c_read_blocking_internal(i2c_inst_t *i2c, uint8_t addr, uint8_t *ds
         if (abort)
             break;
 
-        *dst++ = i2c->hw->data_cmd;
+        *dst++ = (uint8_t) i2c->hw->data_cmd;
     }
 
     int rval;
diff --git a/src/rp2_common/hardware_i2c/include/hardware/i2c.h b/src/rp2_common/hardware_i2c/include/hardware/i2c.h
index dda598c..5f4a74c 100644
--- a/src/rp2_common/hardware_i2c/include/hardware/i2c.h
+++ b/src/rp2_common/hardware_i2c/include/hardware/i2c.h
@@ -293,7 +293,7 @@ static inline void i2c_read_raw_blocking(i2c_inst_t *i2c, uint8_t *dst, size_t l
     for (size_t i = 0; i < len; ++i) {
         while (!i2c_get_read_available(i2c))
             tight_loop_contents();
-        *dst++ = i2c_get_hw(i2c)->data_cmd;
+        *dst++ = (uint8_t)i2c_get_hw(i2c)->data_cmd;
     }
 }
 
diff --git a/src/rp2_common/hardware_irq/irq.c b/src/rp2_common/hardware_irq/irq.c
index 9b68796..54b1125 100644
--- a/src/rp2_common/hardware_irq/irq.c
+++ b/src/rp2_common/hardware_irq/irq.c
@@ -24,7 +24,7 @@ static inline void *add_thumb_bit(void *addr) {
 }
 
 static inline void *remove_thumb_bit(void *addr) {
-    return (void *) (((uintptr_t) addr) & ~0x1);
+    return (void *) (((uintptr_t) addr) & (uint)~0x1);
 }
 
 static void set_raw_irq_handler_and_unlock(uint num, irq_handler_t handler, uint32_t save) {
@@ -139,7 +139,7 @@ static uint16_t make_branch(uint16_t *from, void *to) {
     uint32_t ui_to = (uint32_t)to;
     uint32_t delta = (ui_to - ui_from - 4) / 2;
     assert(!(delta >> 11u));
-    return 0xe000 | (delta & 0x7ff);
+    return (uint16_t)(0xe000 | (delta & 0x7ff));
 }
 
 static void insert_branch_and_link(uint16_t *from, void *to) {
@@ -147,8 +147,8 @@ static void insert_branch_and_link(uint16_t *from, void *to) {
     uint32_t ui_to = (uint32_t)to;
     uint32_t delta = (ui_to - ui_from - 4) / 2;
     assert(!(delta >> 11u));
-    from[0] = 0xf000 | ((delta >> 11u) & 0x7ffu);
-    from[1] = 0xf800 | (delta & 0x7ffu);
+    from[0] = (uint16_t)(0xf000 | ((delta >> 11u) & 0x7ffu));
+    from[1] = (uint16_t)(0xf800 | (delta & 0x7ffu));
 }
 
 static inline void *resolve_branch(uint16_t *inst) {
@@ -174,7 +174,11 @@ static inline int8_t slot_diff(struct irq_handler_chain_slot *to, struct irq_han
         : "l" (from)
         :
         );
-    return result;
+    return (int8_t)result;
+}
+
+static inline int8_t get_slot_index(struct irq_handler_chain_slot *slot) {
+    return slot_diff(slot, irq_handler_chain_slots);
 }
 
 void irq_add_shared_handler(uint num, irq_handler_t handler, uint8_t order_priority) {
@@ -189,7 +193,7 @@ void irq_add_shared_handler(uint num, irq_handler_t handler, uint8_t order_prior
     uint32_t save = spin_lock_blocking(lock);
     hard_assert(irq_hander_chain_free_slot_head >= 0);
     struct irq_handler_chain_slot *slot = &irq_handler_chain_slots[irq_hander_chain_free_slot_head];
-    int slot_index = irq_hander_chain_free_slot_head;
+    int8_t slot_index = irq_hander_chain_free_slot_head;
     irq_hander_chain_free_slot_head = slot->link;
     irq_handler_t vtable_handler = get_vtable()[16 + num];
     if (!is_shared_irq_raw_handler(vtable_handler)) {
@@ -237,7 +241,7 @@ void irq_add_shared_handler(uint num, irq_handler_t handler, uint8_t order_prior
                     .inst1 = 0xa100,                                                    // add r1, pc, #0
                     .inst2 = make_branch(&slot->inst2, irq_handler_chain_first_slot),   // b irq_handler_chain_first_slot
                     .inst3 = make_branch(&slot->inst3, existing_vtable_slot),           // b existing_slot
-                    .link = slot_diff(existing_vtable_slot, irq_handler_chain_slots),
+                    .link = get_slot_index(existing_vtable_slot),
                     .priority = order_priority,
                     .handler = handler
             };
@@ -286,14 +290,14 @@ void irq_remove_handler(uint num, irq_handler_t handler) {
             struct irq_handler_chain_slot *prev_slot = NULL;
             struct irq_handler_chain_slot *existing_vtable_slot = remove_thumb_bit(vtable_handler);
             struct irq_handler_chain_slot *to_free_slot = existing_vtable_slot;
-            int to_free_slot_index = to_free_slot - irq_handler_chain_slots;
+            int8_t to_free_slot_index = get_slot_index(to_free_slot);
             while (to_free_slot->handler != handler) {
                 prev_slot = to_free_slot;
                 if (to_free_slot->link < 0) break;
                 to_free_slot = &irq_handler_chain_slots[to_free_slot->link];
             }
             if (to_free_slot->handler == handler) {
-                int next_slot_index = to_free_slot->link;
+                int8_t next_slot_index = to_free_slot->link;
                 if (next_slot_index >= 0) {
                     // There is another slot in the chain, so copy that over us, so that our inst3 points at something valid
                     // Note this only matters in the exception case anyway, and it that case, we will skip the next handler,
@@ -365,11 +369,11 @@ void irq_add_tail_to_free_list(struct irq_handler_chain_slot *slot) {
     irq_handler_t slot_handler = (irq_handler_t) add_thumb_bit(slot);
     assert(is_shared_irq_raw_handler(slot_handler));
 
-    int exception = __get_current_exception();
+    uint exception = __get_current_exception();
     assert(exception);
     spin_lock_t *lock = spin_lock_instance(PICO_SPINLOCK_ID_IRQ);
     uint32_t save = spin_lock_blocking(lock);
-    int slot_index = slot - irq_handler_chain_slots;
+    int8_t slot_index = get_slot_index(slot);
     if (slot_handler == get_vtable()[exception]) {
         get_vtable()[exception] = __unhandled_user_irq;
     } else {
diff --git a/src/rp2_common/hardware_pio/include/hardware/pio.h b/src/rp2_common/hardware_pio/include/hardware/pio.h
index df4db7d..59717c1 100644
--- a/src/rp2_common/hardware_pio/include/hardware/pio.h
+++ b/src/rp2_common/hardware_pio/include/hardware/pio.h
@@ -185,8 +185,8 @@ static inline void sm_config_set_sideset(pio_sm_config *c, uint bit_count, bool
                  (bit_count << PIO_SM0_PINCTRL_SIDESET_COUNT_LSB);
 
     c->execctrl = (c->execctrl & ~(PIO_SM0_EXECCTRL_SIDE_EN_BITS | PIO_SM0_EXECCTRL_SIDE_PINDIR_BITS)) |
-                  (!!optional << PIO_SM0_EXECCTRL_SIDE_EN_LSB) |
-                  (!!pindirs << PIO_SM0_EXECCTRL_SIDE_PINDIR_LSB);
+                  (bool_to_bit(optional) << PIO_SM0_EXECCTRL_SIDE_EN_LSB) |
+                  (bool_to_bit(pindirs) << PIO_SM0_EXECCTRL_SIDE_PINDIR_LSB);
 }
 
 /*! \brief Set the state machine clock divider (from a floating point value) in a state machine configuration
@@ -205,8 +205,8 @@ static inline void sm_config_set_sideset(pio_sm_config *c, uint bit_count, bool
  *  although it will depend on the use case.
  */
 static inline void sm_config_set_clkdiv(pio_sm_config *c, float div) {
-    uint16_t div_int = (uint16_t) div;
-    uint8_t div_frac = (uint8_t) ((div - div_int) * (1u << 8u));
+    uint div_int = (uint)div;
+    uint div_frac = (uint)((div - (float)div_int) * (1u << 8u));
     c->clkdiv =
             (div_frac << PIO_SM0_CLKDIV_FRAC_LSB) |
             (div_int << PIO_SM0_CLKDIV_INT_LSB);
@@ -227,8 +227,8 @@ static inline void sm_config_set_clkdiv(pio_sm_config *c, float div) {
  */
 static inline void sm_config_set_clkdiv_int_frac(pio_sm_config *c, uint16_t div_int, uint8_t div_frac) {
     c->clkdiv =
-            (div_frac << PIO_SM0_CLKDIV_FRAC_LSB) |
-            (div_int << PIO_SM0_CLKDIV_INT_LSB);
+            (((uint)div_frac) << PIO_SM0_CLKDIV_FRAC_LSB) |
+            (((uint)div_int) << PIO_SM0_CLKDIV_INT_LSB);
 }
 
 /*! \brief Set the wrap addresses in a state machine configuration
@@ -273,8 +273,8 @@ static inline void sm_config_set_in_shift(pio_sm_config *c, bool shift_right, bo
                     ~(PIO_SM0_SHIFTCTRL_IN_SHIFTDIR_BITS |
                       PIO_SM0_SHIFTCTRL_AUTOPUSH_BITS |
                       PIO_SM0_SHIFTCTRL_PUSH_THRESH_BITS)) |
-                   (!!shift_right << PIO_SM0_SHIFTCTRL_IN_SHIFTDIR_LSB) |
-                   (!!autopush << PIO_SM0_SHIFTCTRL_AUTOPUSH_LSB) |
+                   (bool_to_bit(shift_right) << PIO_SM0_SHIFTCTRL_IN_SHIFTDIR_LSB) |
+                   (bool_to_bit(autopush) << PIO_SM0_SHIFTCTRL_AUTOPUSH_LSB) |
                    ((push_threshold & 0x1fu) << PIO_SM0_SHIFTCTRL_PUSH_THRESH_LSB);
 }
 
@@ -292,8 +292,8 @@ static inline void sm_config_set_out_shift(pio_sm_config *c, bool shift_right, b
                     ~(PIO_SM0_SHIFTCTRL_OUT_SHIFTDIR_BITS |
                       PIO_SM0_SHIFTCTRL_AUTOPULL_BITS |
                       PIO_SM0_SHIFTCTRL_PULL_THRESH_BITS)) |
-                   (!!shift_right << PIO_SM0_SHIFTCTRL_OUT_SHIFTDIR_LSB) |
-                   (!!autopull << PIO_SM0_SHIFTCTRL_AUTOPULL_LSB) |
+                   (bool_to_bit(shift_right) << PIO_SM0_SHIFTCTRL_OUT_SHIFTDIR_LSB) |
+                   (bool_to_bit(autopull) << PIO_SM0_SHIFTCTRL_AUTOPULL_LSB) |
                    ((pull_threshold & 0x1fu) << PIO_SM0_SHIFTCTRL_PULL_THRESH_LSB);
 }
 
@@ -305,8 +305,8 @@ static inline void sm_config_set_out_shift(pio_sm_config *c, bool shift_right, b
  */
 static inline void sm_config_set_fifo_join(pio_sm_config *c, enum pio_fifo_join join) {
     assert(join >= 0 && join <= 2);
-    c->shiftctrl = (c->shiftctrl & ~(PIO_SM0_SHIFTCTRL_FJOIN_TX_BITS | PIO_SM0_SHIFTCTRL_FJOIN_RX_BITS)) |
-                   (join << PIO_SM0_SHIFTCTRL_FJOIN_TX_LSB);
+    c->shiftctrl = (c->shiftctrl & (uint)~(PIO_SM0_SHIFTCTRL_FJOIN_TX_BITS | PIO_SM0_SHIFTCTRL_FJOIN_RX_BITS)) |
+                   (((uint)join) << PIO_SM0_SHIFTCTRL_FJOIN_TX_LSB);
 }
 
 /*! \brief Set special 'out' operations in a state machine configuration
@@ -317,12 +317,12 @@ static inline void sm_config_set_fifo_join(pio_sm_config *c, enum pio_fifo_join
  * \param has_enable_pin true to enable auxiliary OUT enable pin 
  * \param enable_pin_index pin index for auxiliary OUT enable
  */
-static inline void sm_config_set_out_special(pio_sm_config *c, bool sticky, bool has_enable_pin, int enable_pin_index) {
+static inline void sm_config_set_out_special(pio_sm_config *c, bool sticky, bool has_enable_pin, uint enable_pin_index) {
     c->execctrl = (c->execctrl &
-                   ~(PIO_SM0_EXECCTRL_OUT_STICKY_BITS | PIO_SM0_EXECCTRL_INLINE_OUT_EN_BITS |
+                   (uint)~(PIO_SM0_EXECCTRL_OUT_STICKY_BITS | PIO_SM0_EXECCTRL_INLINE_OUT_EN_BITS |
                      PIO_SM0_EXECCTRL_OUT_EN_SEL_BITS)) |
-                  (!!sticky << PIO_SM0_EXECCTRL_OUT_STICKY_LSB) |
-                  (!!has_enable_pin << PIO_SM0_EXECCTRL_INLINE_OUT_EN_LSB) |
+                  (bool_to_bit(sticky) << PIO_SM0_EXECCTRL_OUT_STICKY_LSB) |
+                  (bool_to_bit(has_enable_pin) << PIO_SM0_EXECCTRL_INLINE_OUT_EN_LSB) |
                   ((enable_pin_index << PIO_SM0_EXECCTRL_OUT_EN_SEL_LSB) & PIO_SM0_EXECCTRL_OUT_EN_SEL_BITS);
 }
 
@@ -336,7 +336,7 @@ static inline void sm_config_set_out_special(pio_sm_config *c, bool sticky, bool
 static inline void sm_config_set_mov_status(pio_sm_config *c, enum pio_mov_status_type status_sel, uint status_n) {
     c->execctrl = (c->execctrl
                    & ~(PIO_SM0_EXECCTRL_STATUS_SEL_BITS | PIO_SM0_EXECCTRL_STATUS_N_BITS))
-                  | ((status_sel << PIO_SM0_EXECCTRL_STATUS_SEL_LSB) & PIO_SM0_EXECCTRL_STATUS_SEL_BITS)
+                  | ((((uint)status_sel) << PIO_SM0_EXECCTRL_STATUS_SEL_LSB) & PIO_SM0_EXECCTRL_STATUS_SEL_BITS)
                   | ((status_n << PIO_SM0_EXECCTRL_STATUS_N_LSB) & PIO_SM0_EXECCTRL_STATUS_N_BITS);
 }
 
@@ -515,7 +515,7 @@ void pio_sm_init(PIO pio, uint sm, uint initial_pc, const pio_sm_config *config)
  * \param enabled true to enable the state machine; false to disable
  */
 static inline void pio_sm_set_enabled(PIO pio, uint sm, bool enabled) {
-    pio->ctrl = (pio->ctrl & ~(1u << sm)) | (!!enabled << sm);
+    pio->ctrl = (pio->ctrl & ~(1u << sm)) | (bool_to_bit(enabled) << sm);
 }
 
 /*! \brief Enable or disable multiple PIO state machines
@@ -853,7 +853,7 @@ static inline bool pio_sm_is_rx_fifo_empty(PIO pio, uint sm) {
  */
 static inline uint pio_sm_get_rx_fifo_level(PIO pio, uint sm) {
     check_sm_param(sm);
-    int bitoffs = PIO_FLEVEL_RX0_LSB + sm * (PIO_FLEVEL_RX1_LSB - PIO_FLEVEL_RX0_LSB);
+    uint bitoffs = PIO_FLEVEL_RX0_LSB + sm * (PIO_FLEVEL_RX1_LSB - PIO_FLEVEL_RX0_LSB);
     const uint32_t mask = PIO_FLEVEL_RX0_BITS >> PIO_FLEVEL_RX0_LSB;
     return (pio->flevel >> bitoffs) & mask;
 }
@@ -945,8 +945,8 @@ void pio_sm_drain_tx_fifo(PIO pio, uint sm);
  */
 static inline void pio_sm_set_clkdiv(PIO pio, uint sm, float div) {
     check_sm_param(sm);
-    uint16_t div_int = (uint16_t) div;
-    uint8_t div_frac = (uint8_t) ((div - div_int) * (1u << 8u));
+    uint div_int = (uint16_t) div;
+    uint div_frac = (uint8_t) ((div - (float)div_int) * (1u << 8u));
     pio->sm[sm].clkdiv =
             (div_frac << PIO_SM0_CLKDIV_FRAC_LSB) |
             (div_int << PIO_SM0_CLKDIV_INT_LSB);
@@ -963,8 +963,8 @@ static inline void pio_sm_set_clkdiv(PIO pio, uint sm, float div) {
 static inline void pio_sm_set_clkdiv_int_frac(PIO pio, uint sm, uint16_t div_int, uint8_t div_frac) {
     check_sm_param(sm);
     pio->sm[sm].clkdiv =
-            (div_frac << PIO_SM0_CLKDIV_FRAC_LSB) |
-            (div_int << PIO_SM0_CLKDIV_INT_LSB);
+            (((uint)div_frac) << PIO_SM0_CLKDIV_FRAC_LSB) |
+            (((uint)div_int) << PIO_SM0_CLKDIV_INT_LSB);
 }
 
 /*! \brief Clear a state machine's TX and RX FIFOs
diff --git a/src/rp2_common/hardware_pio/pio.c b/src/rp2_common/hardware_pio/pio.c
index 0ae79db..a707928 100644
--- a/src/rp2_common/hardware_pio/pio.c
+++ b/src/rp2_common/hardware_pio/pio.c
@@ -43,11 +43,11 @@ void pio_sm_unclaim(PIO pio, uint sm) {
 
 int pio_claim_unused_sm(PIO pio, bool required) {
     // PIO index is 0 or 1.
-    int which = (int)pio_get_index(pio);
-    int base = which * NUM_PIO_STATE_MACHINES;
+    uint which = pio_get_index(pio);
+    uint base = which * NUM_PIO_STATE_MACHINES;
     int index = hw_claim_unused_from_range((uint8_t*)&claimed, required, base,
                                       base + NUM_PIO_STATE_MACHINES - 1, "No PIO state machines are available");
-    return index >= base ? index - base : -1;
+    return index >= (int)base ? index - (int)base : -1;
 }
 
 static_assert(PIO_INSTRUCTION_COUNT <= 32, "");
@@ -113,9 +113,9 @@ uint pio_add_program(PIO pio, const pio_program_t *program) {
     if (offset < 0) {
         panic("No program space");
     }
-    _pio_add_program_at_offset(pio, program, offset);
+    _pio_add_program_at_offset(pio, program, (uint)offset);
     hw_claim_unlock(save);
-    return offset;
+    return (uint)offset;
 }
 
 void pio_add_program_at_offset(PIO pio, const pio_program_t *program, uint offset) {
@@ -166,7 +166,7 @@ void pio_sm_set_pins(PIO pio, uint sm, uint32_t pins) {
 void pio_sm_set_pins_with_mask(PIO pio, uint sm, uint32_t pinvals, uint32_t pin_mask) {
     uint32_t pinctrl_saved = pio->sm[sm].pinctrl;
     while (pin_mask) {
-        uint base = __builtin_ctz(pin_mask);
+        uint base = (uint)__builtin_ctz(pin_mask);
         pio->sm[sm].pinctrl =
                 (1u << PIO_SM0_PINCTRL_SET_COUNT_LSB) |
                 (base << PIO_SM0_PINCTRL_SET_BASE_LSB);
@@ -179,7 +179,7 @@ void pio_sm_set_pins_with_mask(PIO pio, uint sm, uint32_t pinvals, uint32_t pin_
 void pio_sm_set_pindirs_with_mask(PIO pio, uint sm, uint32_t pindirs, uint32_t pin_mask) {
     uint32_t pinctrl_saved = pio->sm[sm].pinctrl;
     while (pin_mask) {
-        uint base = __builtin_ctz(pin_mask);
+        uint base = (uint)__builtin_ctz(pin_mask);
         pio->sm[sm].pinctrl =
                 (1u << PIO_SM0_PINCTRL_SET_COUNT_LSB) |
                 (base << PIO_SM0_PINCTRL_SET_BASE_LSB);
diff --git a/src/rp2_common/hardware_pll/include/hardware/pll.h b/src/rp2_common/hardware_pll/include/hardware/pll.h
index 023e340..ee0c3ae 100644
--- a/src/rp2_common/hardware_pll/include/hardware/pll.h
+++ b/src/rp2_common/hardware_pll/include/hardware/pll.h
@@ -39,7 +39,7 @@ typedef pll_hw_t *PLL;
  * \param post_div1 Post Divider 1 - range 1-7. Must be >= post_div2
  * \param post_div2 Post Divider 2 - range 1-7
  */
-void pll_init(PLL pll, uint32_t ref_div, uint32_t vco_freq, uint32_t post_div1, uint8_t post_div2);
+void pll_init(PLL pll, uint ref_div, uint vco_freq, uint post_div1, uint post_div2);
 
 /*! \brief Release/uninitialise specified PLL.
  *  \ingroup hardware_pll
diff --git a/src/rp2_common/hardware_pll/pll.c b/src/rp2_common/hardware_pll/pll.c
index a55ed5c..4daeb51 100644
--- a/src/rp2_common/hardware_pll/pll.c
+++ b/src/rp2_common/hardware_pll/pll.c
@@ -9,7 +9,7 @@
 #include "hardware/pll.h"
 
 /// \tag::pll_init_calculations[]
-void pll_init(PLL pll, uint32_t refdiv, uint32_t vco_freq, uint32_t post_div1, uint8_t post_div2) {
+void pll_init(PLL pll, uint refdiv, uint vco_freq, uint post_div1, uint post_div2) {
     // Turn off PLL in case it is already running
     pll->pwr = 0xffffffff;
     pll->fbdiv_int = 0;
diff --git a/src/rp2_common/hardware_pwm/include/hardware/pwm.h b/src/rp2_common/hardware_pwm/include/hardware/pwm.h
index 58aa6e8..768dae5 100644
--- a/src/rp2_common/hardware_pwm/include/hardware/pwm.h
+++ b/src/rp2_common/hardware_pwm/include/hardware/pwm.h
@@ -102,7 +102,7 @@ static inline uint pwm_gpio_to_channel(uint gpio) {
  */
 static inline void pwm_config_set_phase_correct(pwm_config *c, bool phase_correct) {
     c->csr = (c->csr & ~PWM_CH0_CSR_PH_CORRECT_BITS)
-        | (!!phase_correct << PWM_CH0_CSR_PH_CORRECT_LSB);
+        | (bool_to_bit(phase_correct) << PWM_CH0_CSR_PH_CORRECT_LSB);
 }
 
 /** \brief Set clock divider in a PWM configuration
@@ -146,7 +146,7 @@ static inline void pwm_config_set_clkdiv_int(pwm_config *c, uint div) {
 static inline void pwm_config_set_clkdiv_mode(pwm_config *c, enum pwm_clkdiv_mode mode) {
     valid_params_if(PWM, mode >= PWM_DIV_FREE_RUNNING && mode <= PWM_DIV_B_FALLING);
     c->csr = (c->csr & ~PWM_CH0_CSR_DIVMODE_BITS)
-        | (mode << PWM_CH0_CSR_DIVMODE_LSB);
+        | (((uint)mode) << PWM_CH0_CSR_DIVMODE_LSB);
 }
 
 /** \brief Set output polarity in a PWM configuration
@@ -158,7 +158,7 @@ static inline void pwm_config_set_clkdiv_mode(pwm_config *c, enum pwm_clkdiv_mod
  */
 static inline void pwm_config_set_output_polarity(pwm_config *c, bool a, bool b) {
     c->csr = (c->csr & ~(PWM_CH0_CSR_A_INV_BITS | PWM_CH0_CSR_B_INV_BITS))
-        | ((!!a << PWM_CH0_CSR_A_INV_LSB) | (!!b << PWM_CH0_CSR_B_INV_LSB));
+        | ((bool_to_bit(a) << PWM_CH0_CSR_A_INV_LSB) | (bool_to_bit(b) << PWM_CH0_CSR_B_INV_LSB));
 }
 
 /** \brief Set PWM counter wrap value in a PWM configuration
@@ -192,7 +192,7 @@ static inline void pwm_init(uint slice_num, pwm_config *c, bool start) {
     pwm_hw->slice[slice_num].cc = PWM_CH0_CC_RESET;
     pwm_hw->slice[slice_num].top = c->top;
     pwm_hw->slice[slice_num].div = c->div;
-    pwm_hw->slice[slice_num].csr = c->csr | (!!start << PWM_CH0_CSR_EN_LSB);
+    pwm_hw->slice[slice_num].csr = c->csr | (bool_to_bit(start) << PWM_CH0_CSR_EN_LSB);
 }
 
 /** \brief Get a set of default values for PWM configuration
@@ -252,7 +252,7 @@ static inline void pwm_set_chan_level(uint slice_num, uint chan, uint16_t level)
     check_slice_num_param(slice_num);
     hw_write_masked(
         &pwm_hw->slice[slice_num].cc,
-        level << (chan ? PWM_CH0_CC_B_LSB : PWM_CH0_CC_A_LSB),
+        ((uint)level) << (chan ? PWM_CH0_CC_B_LSB : PWM_CH0_CC_A_LSB),
         chan ? PWM_CH0_CC_B_BITS : PWM_CH0_CC_A_BITS
     );
 }
@@ -274,7 +274,7 @@ static inline void pwm_set_chan_level(uint slice_num, uint chan, uint16_t level)
  */
 static inline void pwm_set_both_levels(uint slice_num, uint16_t level_a, uint16_t level_b) {
     check_slice_num_param(slice_num);
-    pwm_hw->slice[slice_num].cc = (level_b << PWM_CH0_CC_B_LSB) | (level_a << PWM_CH0_CC_A_LSB);
+    pwm_hw->slice[slice_num].cc = (((uint)level_b) << PWM_CH0_CC_B_LSB) | (((uint)level_a) << PWM_CH0_CC_A_LSB);
 }
 
 /** \brief Helper function to set the PWM level for the slice and channel associated with a GPIO.
@@ -310,7 +310,7 @@ static inline void pwm_set_gpio_level(uint gpio, uint16_t level) {
  */
 static inline uint16_t pwm_get_counter(uint slice_num) {
     check_slice_num_param(slice_num);
-    return (pwm_hw->slice[slice_num].ctr);
+    return (uint16_t)(pwm_hw->slice[slice_num].ctr);
 }
 
 /** \brief Set PWM counter
@@ -373,7 +373,7 @@ static inline void pwm_retard_count(uint slice_num) {
 static inline void pwm_set_clkdiv_int_frac(uint slice_num, uint8_t integer, uint8_t fract) {
     check_slice_num_param(slice_num);
     valid_params_if(PWM, fract < 16);
-    pwm_hw->slice[slice_num].div = (integer << PWM_CH0_DIV_INT_LSB) | (fract << PWM_CH0_DIV_FRAC_LSB);
+    pwm_hw->slice[slice_num].div = (((uint)integer) << PWM_CH0_DIV_INT_LSB) | (((uint)fract) << PWM_CH0_DIV_FRAC_LSB);
 }
 
 /** \brief Set PWM clock divider
@@ -401,7 +401,7 @@ static inline void pwm_set_clkdiv(uint slice_num, float divider) {
  */
 static inline void pwm_set_output_polarity(uint slice_num, bool a, bool b) {
     check_slice_num_param(slice_num);
-    hw_write_masked(&pwm_hw->slice[slice_num].csr, !!a << PWM_CH0_CSR_A_INV_LSB | !!b << PWM_CH0_CSR_B_INV_LSB,
+    hw_write_masked(&pwm_hw->slice[slice_num].csr, bool_to_bit(a) << PWM_CH0_CSR_A_INV_LSB | bool_to_bit(b) << PWM_CH0_CSR_B_INV_LSB,
                      PWM_CH0_CSR_A_INV_BITS | PWM_CH0_CSR_B_INV_BITS);
 }
 
@@ -415,7 +415,7 @@ static inline void pwm_set_output_polarity(uint slice_num, bool a, bool b) {
 static inline void pwm_set_clkdiv_mode(uint slice_num, enum pwm_clkdiv_mode mode) {
     check_slice_num_param(slice_num);
     valid_params_if(PWM, mode >= PWM_DIV_FREE_RUNNING && mode <= PWM_DIV_B_FALLING);
-    hw_write_masked(&pwm_hw->slice[slice_num].csr, mode << PWM_CH0_CSR_DIVMODE_LSB, PWM_CH0_CSR_DIVMODE_BITS);
+    hw_write_masked(&pwm_hw->slice[slice_num].csr, ((uint)mode) << PWM_CH0_CSR_DIVMODE_LSB, PWM_CH0_CSR_DIVMODE_BITS);
 }
 
 /** \brief Set PWM phase correct on/off
@@ -429,7 +429,7 @@ static inline void pwm_set_clkdiv_mode(uint slice_num, enum pwm_clkdiv_mode mode
  */
 static inline void pwm_set_phase_correct(uint slice_num, bool phase_correct) {
     check_slice_num_param(slice_num);
-    hw_write_masked(&pwm_hw->slice[slice_num].csr, phase_correct << PWM_CH0_CSR_PH_CORRECT_LSB, PWM_CH0_CSR_PH_CORRECT_BITS);
+    hw_write_masked(&pwm_hw->slice[slice_num].csr, bool_to_bit(phase_correct) << PWM_CH0_CSR_PH_CORRECT_LSB, PWM_CH0_CSR_PH_CORRECT_BITS);
 }
 
 /** \brief Enable/Disable PWM
@@ -440,7 +440,7 @@ static inline void pwm_set_phase_correct(uint slice_num, bool phase_correct) {
  */
 static inline void pwm_set_enabled(uint slice_num, bool enabled) {
     check_slice_num_param(slice_num);
-    hw_write_masked(&pwm_hw->slice[slice_num].csr, !!enabled << PWM_CH0_CSR_EN_LSB, PWM_CH0_CSR_EN_BITS);
+    hw_write_masked(&pwm_hw->slice[slice_num].csr, bool_to_bit(enabled) << PWM_CH0_CSR_EN_LSB, PWM_CH0_CSR_EN_BITS);
 }
 
 /** \brief Enable/Disable multiple PWM slices simultaneously
@@ -500,7 +500,7 @@ static inline void pwm_clear_irq(uint slice_num) {
  *
  * \return Bitmask of all PWM interrupts currently set
  */
-static inline int32_t pwm_get_irq_status_mask(void) {
+static inline uint32_t pwm_get_irq_status_mask(void) {
     return pwm_hw->ints;
 }
 
diff --git a/src/rp2_common/hardware_rtc/rtc.c b/src/rp2_common/hardware_rtc/rtc.c
index 91bd199..5337d33 100644
--- a/src/rp2_common/hardware_rtc/rtc.c
+++ b/src/rp2_common/hardware_rtc/rtc.c
@@ -65,13 +65,13 @@ bool rtc_set_datetime(datetime_t *t) {
     }
 
     // Write to setup registers
-    rtc_hw->setup_0 = (t->year  << RTC_SETUP_0_YEAR_LSB ) |
-                      (t->month << RTC_SETUP_0_MONTH_LSB) |
-                      (t->day   << RTC_SETUP_0_DAY_LSB);
-    rtc_hw->setup_1 = (t->dotw  << RTC_SETUP_1_DOTW_LSB) |
-                      (t->hour  << RTC_SETUP_1_HOUR_LSB) |
-                      (t->min   << RTC_SETUP_1_MIN_LSB)  |
-                      (t->sec   << RTC_SETUP_1_SEC_LSB);
+    rtc_hw->setup_0 = (((uint)t->year)  << RTC_SETUP_0_YEAR_LSB ) |
+                      (((uint)t->month) << RTC_SETUP_0_MONTH_LSB) |
+                      (((uint)t->day)   << RTC_SETUP_0_DAY_LSB);
+    rtc_hw->setup_1 = (((uint)t->dotw)  << RTC_SETUP_1_DOTW_LSB) |
+                      (((uint)t->hour)  << RTC_SETUP_1_HOUR_LSB) |
+                      (((uint)t->min)   << RTC_SETUP_1_MIN_LSB)  |
+                      (((uint)t->sec)   << RTC_SETUP_1_SEC_LSB);
 
     // Load setup values into rtc clock domain
     rtc_hw->ctrl = RTC_CTRL_LOAD_BITS;
@@ -131,13 +131,13 @@ static void rtc_irq_handler(void) {
 static bool rtc_alarm_repeats(datetime_t *t) {
     // If any value is set to -1 then we don't match on that value
     // hence the alarm will eventually repeat
-    if (t->year  == -1) return true;
-    if (t->month == -1) return true;
-    if (t->day   == -1) return true;
-    if (t->dotw  == -1) return true;
-    if (t->hour  == -1) return true;
-    if (t->min   == -1) return true;
-    if (t->sec   == -1) return true;
+    if (t->year  < 0) return true;
+    if (t->month < 0) return true;
+    if (t->day   < 0) return true;
+    if (t->dotw  < 0) return true;
+    if (t->hour  < 0) return true;
+    if (t->min   < 0) return true;
+    if (t->sec   < 0) return true;
     return false;
 }
 
@@ -145,22 +145,22 @@ void rtc_set_alarm(datetime_t *t, rtc_callback_t user_callback) {
     rtc_disable_alarm();
 
     // Only add to setup if it isn't -1
-    rtc_hw->irq_setup_0 = ((t->year  == -1) ? 0 : (t->year  << RTC_IRQ_SETUP_0_YEAR_LSB )) |
-                          ((t->month == -1) ? 0 : (t->month << RTC_IRQ_SETUP_0_MONTH_LSB)) |
-                          ((t->day   == -1) ? 0 : (t->day   << RTC_IRQ_SETUP_0_DAY_LSB  ));
-    rtc_hw->irq_setup_1 = ((t->dotw  == -1) ? 0 : (t->dotw  << RTC_IRQ_SETUP_1_DOTW_LSB)) |
-                          ((t->hour  == -1) ? 0 : (t->hour  << RTC_IRQ_SETUP_1_HOUR_LSB)) |
-                          ((t->min   == -1) ? 0 : (t->min   << RTC_IRQ_SETUP_1_MIN_LSB )) |
-                          ((t->sec   == -1) ? 0 : (t->sec   << RTC_IRQ_SETUP_1_SEC_LSB ));
+    rtc_hw->irq_setup_0 = ((t->year  < 0) ? 0 : (((uint)t->year)  << RTC_IRQ_SETUP_0_YEAR_LSB )) |
+                          ((t->month < 0) ? 0 : (((uint)t->month) << RTC_IRQ_SETUP_0_MONTH_LSB)) |
+                          ((t->day   < 0) ? 0 : (((uint)t->day)   << RTC_IRQ_SETUP_0_DAY_LSB  ));
+    rtc_hw->irq_setup_1 = ((t->dotw  < 0) ? 0 : (((uint)t->dotw)  << RTC_IRQ_SETUP_1_DOTW_LSB)) |
+                          ((t->hour  < 0) ? 0 : (((uint)t->hour)  << RTC_IRQ_SETUP_1_HOUR_LSB)) |
+                          ((t->min   < 0) ? 0 : (((uint)t->min)   << RTC_IRQ_SETUP_1_MIN_LSB )) |
+                          ((t->sec   < 0) ? 0 : (((uint)t->sec)   << RTC_IRQ_SETUP_1_SEC_LSB ));
 
     // Set the match enable bits for things we care about
-    if (t->year  != -1) hw_set_bits(&rtc_hw->irq_setup_0, RTC_IRQ_SETUP_0_YEAR_ENA_BITS);
-    if (t->month != -1) hw_set_bits(&rtc_hw->irq_setup_0, RTC_IRQ_SETUP_0_MONTH_ENA_BITS);
-    if (t->day   != -1) hw_set_bits(&rtc_hw->irq_setup_0, RTC_IRQ_SETUP_0_DAY_ENA_BITS);
-    if (t->dotw  != -1) hw_set_bits(&rtc_hw->irq_setup_1, RTC_IRQ_SETUP_1_DOTW_ENA_BITS);
-    if (t->hour  != -1) hw_set_bits(&rtc_hw->irq_setup_1, RTC_IRQ_SETUP_1_HOUR_ENA_BITS);
-    if (t->min   != -1) hw_set_bits(&rtc_hw->irq_setup_1, RTC_IRQ_SETUP_1_MIN_ENA_BITS);
-    if (t->sec   != -1) hw_set_bits(&rtc_hw->irq_setup_1, RTC_IRQ_SETUP_1_SEC_ENA_BITS);
+    if (t->year  >= 0) hw_set_bits(&rtc_hw->irq_setup_0, RTC_IRQ_SETUP_0_YEAR_ENA_BITS);
+    if (t->month >= 0) hw_set_bits(&rtc_hw->irq_setup_0, RTC_IRQ_SETUP_0_MONTH_ENA_BITS);
+    if (t->day   >= 0) hw_set_bits(&rtc_hw->irq_setup_0, RTC_IRQ_SETUP_0_DAY_ENA_BITS);
+    if (t->dotw  >= 0) hw_set_bits(&rtc_hw->irq_setup_1, RTC_IRQ_SETUP_1_DOTW_ENA_BITS);
+    if (t->hour  >= 0) hw_set_bits(&rtc_hw->irq_setup_1, RTC_IRQ_SETUP_1_HOUR_ENA_BITS);
+    if (t->min   >= 0) hw_set_bits(&rtc_hw->irq_setup_1, RTC_IRQ_SETUP_1_MIN_ENA_BITS);
+    if (t->sec   >= 0) hw_set_bits(&rtc_hw->irq_setup_1, RTC_IRQ_SETUP_1_SEC_ENA_BITS);
 
     // Does it repeat? I.e. do we not match on any of the bits
     _alarm_repeats = rtc_alarm_repeats(t);
diff --git a/src/rp2_common/hardware_spi/include/hardware/spi.h b/src/rp2_common/hardware_spi/include/hardware/spi.h
index a4cf986..0d29043 100644
--- a/src/rp2_common/hardware_spi/include/hardware/spi.h
+++ b/src/rp2_common/hardware_spi/include/hardware/spi.h
@@ -143,9 +143,9 @@ static inline void spi_set_format(spi_inst_t *spi, uint data_bits, spi_cpol_t cp
     invalid_params_if(SPI, cpol != SPI_CPOL_0 && cpol != SPI_CPOL_1);
     invalid_params_if(SPI, cpha != SPI_CPHA_0 && cpha != SPI_CPHA_1);
     hw_write_masked(&spi_get_hw(spi)->cr0,
-        (data_bits - 1) << SPI_SSPCR0_DSS_LSB |
-        cpol << SPI_SSPCR0_SPO_LSB |
-        cpha << SPI_SSPCR0_SPH_LSB,
+                    ((uint)(data_bits - 1)) << SPI_SSPCR0_DSS_LSB |
+                    ((uint)cpol) << SPI_SSPCR0_SPO_LSB |
+                    ((uint)cpha) << SPI_SSPCR0_SPH_LSB,
         SPI_SSPCR0_DSS_BITS |
         SPI_SSPCR0_SPO_BITS |
         SPI_SSPCR0_SPH_BITS);
diff --git a/src/rp2_common/hardware_spi/spi.c b/src/rp2_common/hardware_spi/spi.c
index b0cad30..175d199 100644
--- a/src/rp2_common/hardware_spi/spi.c
+++ b/src/rp2_common/hardware_spi/spi.c
@@ -68,6 +68,8 @@ uint spi_set_baudrate(spi_inst_t *spi, uint baudrate) {
 // Write len bytes from src to SPI. Simultaneously read len bytes from SPI to dst.
 // Note this function is guaranteed to exit in a known amount of time (bits sent * time per bit)
 int __not_in_flash_func(spi_write_read_blocking)(spi_inst_t *spi, const uint8_t *src, uint8_t *dst, size_t len) {
+    invalid_params_if(SPI, 0 > (int)len);
+
     // Never have more transfers in flight than will fit into the RX FIFO,
     // else FIFO will overflow if this code is heavily interrupted.
     const size_t fifo_depth = 8;
@@ -84,11 +86,12 @@ int __not_in_flash_func(spi_write_read_blocking)(spi_inst_t *spi, const uint8_t
         }
     }
 
-    return len;
+    return (int)len;
 }
 
 // Write len bytes directly from src to the SPI, and discard any data received back
 int __not_in_flash_func(spi_write_blocking)(spi_inst_t *spi, const uint8_t *src, size_t len) {
+    invalid_params_if(SPI, 0 > (int)len);
     // Write to TX FIFO whilst ignoring RX, then clean up afterward. When RX
     // is full, PL022 inhibits RX pushes, and sets a sticky flag on
     // push-on-full, but continues shifting. Safe if SSPIMSC_RORIM is not set.
@@ -109,7 +112,7 @@ int __not_in_flash_func(spi_write_blocking)(spi_inst_t *spi, const uint8_t *src,
     // Don't leave overrun flag set
     spi_get_hw(spi)->icr = SPI_SSPICR_RORIC_BITS;
 
-    return len;
+    return (int)len;
 }
 
 // Read len bytes directly from the SPI to dst.
@@ -117,6 +120,7 @@ int __not_in_flash_func(spi_write_blocking)(spi_inst_t *spi, const uint8_t *src,
 // Generally this can be 0, but some devices require a specific value here,
 // e.g. SD cards expect 0xff
 int __not_in_flash_func(spi_read_blocking)(spi_inst_t *spi, uint8_t repeated_tx_data, uint8_t *dst, size_t len) {
+    invalid_params_if(SPI, 0 > (int)len);
     const size_t fifo_depth = 8;
     size_t rx_remaining = len, tx_remaining = len;
 
@@ -131,11 +135,12 @@ int __not_in_flash_func(spi_read_blocking)(spi_inst_t *spi, uint8_t repeated_tx_
         }
     }
 
-    return len;
+    return (int)len;
 }
 
 // Write len halfwords from src to SPI. Simultaneously read len halfwords from SPI to dst.
 int __not_in_flash_func(spi_write16_read16_blocking)(spi_inst_t *spi, const uint16_t *src, uint16_t *dst, size_t len) {
+    invalid_params_if(SPI, 0 > (int)len);
     // Never have more transfers in flight than will fit into the RX FIFO,
     // else FIFO will overflow if this code is heavily interrupted.
     const size_t fifo_depth = 8;
@@ -152,11 +157,12 @@ int __not_in_flash_func(spi_write16_read16_blocking)(spi_inst_t *spi, const uint
         }
     }
 
-    return len;
+    return (int)len;
 }
 
 // Write len bytes directly from src to the SPI, and discard any data received back
 int __not_in_flash_func(spi_write16_blocking)(spi_inst_t *spi, const uint16_t *src, size_t len) {
+    invalid_params_if(SPI, 0 > (int)len);
     // Deliberately overflow FIFO, then clean up afterward, to minimise amount
     // of APB polling required per halfword
     for (size_t i = 0; i < len; ++i) {
@@ -175,12 +181,13 @@ int __not_in_flash_func(spi_write16_blocking)(spi_inst_t *spi, const uint16_t *s
     // Don't leave overrun flag set
     spi_get_hw(spi)->icr = SPI_SSPICR_RORIC_BITS;
 
-    return len;
+    return (int)len;
 }
 
 // Read len halfwords directly from the SPI to dst.
 // repeated_tx_data is output repeatedly on SO as data is read in from SI.
 int __not_in_flash_func(spi_read16_blocking)(spi_inst_t *spi, uint16_t repeated_tx_data, uint16_t *dst, size_t len) {
+    invalid_params_if(SPI, 0 > (int)len);
     const size_t fifo_depth = 8;
     size_t rx_remaining = len, tx_remaining = len;
 
@@ -195,5 +202,5 @@ int __not_in_flash_func(spi_read16_blocking)(spi_inst_t *spi, uint16_t repeated_
         }
     }
 
-    return len;
+    return (int)len;
 }
diff --git a/src/rp2_common/hardware_sync/include/hardware/sync.h b/src/rp2_common/hardware_sync/include/hardware/sync.h
index a2c0d5c..2452b71 100644
--- a/src/rp2_common/hardware_sync/include/hardware/sync.h
+++ b/src/rp2_common/hardware_sync/include/hardware/sync.h
@@ -15,7 +15,6 @@
 extern "C" {
 #endif
 
-
 /** \file hardware/sync.h
  *  \defgroup hardware_sync hardware_sync
  *
@@ -30,6 +29,11 @@ extern "C" {
  * functionality may break or not function optimally
  */
 
+// PICO_CONFIG: PARAM_ASSERTIONS_ENABLED_SYNC, Enable/disable SYNC assertions, type=bool, default=0, group=hardware_SYNC
+#ifndef PARAM_ASSERTIONS_ENABLED_SYNC
+#define PARAM_ASSERTIONS_ENABLED_SYNC 0
+#endif
+
 /** \brief A spin lock identifier
  * \ingroup hardware_sync
  */
@@ -205,7 +209,9 @@ inline static spin_lock_t *spin_lock_instance(uint lock_num) {
  * \return The Spinlock ID
  */
 inline static uint spin_lock_get_num(spin_lock_t *lock) {
-    return lock - (spin_lock_t *) (SIO_BASE + SIO_SPINLOCK0_OFFSET);
+    int lock_num = lock - (spin_lock_t *) (SIO_BASE + SIO_SPINLOCK0_OFFSET);
+    invalid_params_if(SYNC, lock_num < 0 || lock_num >= NUM_SPIN_LOCKS);
+    return (uint) lock_num;
 }
 
 /*! \brief Acquire a spin lock without disabling interrupts (hence unsafe)
@@ -250,9 +256,9 @@ inline static uint32_t spin_lock_blocking(spin_lock_t *lock) {
  *
  * \param lock Spinlock instance
  */
-inline static bool is_spin_locked(const spin_lock_t *lock) {
+inline static bool is_spin_locked(spin_lock_t *lock) {
     check_hw_size(spin_lock_t, 4);
-    uint32_t lock_num = lock - spin_lock_instance(0);
+    uint lock_num = spin_lock_get_num(lock);
     return 0 != (*(io_ro_32 *) (SIO_BASE + SIO_SPINLOCK_ST_OFFSET) & (1u << lock_num));
 }
 
diff --git a/src/rp2_common/hardware_timer/include/hardware/timer.h b/src/rp2_common/hardware_timer/include/hardware/timer.h
index d8a2e1c..6b07abd 100644
--- a/src/rp2_common/hardware_timer/include/hardware/timer.h
+++ b/src/rp2_common/hardware_timer/include/hardware/timer.h
@@ -106,7 +106,7 @@ void busy_wait_until(absolute_time_t t);
  */
 static inline bool time_reached(absolute_time_t t) {
     uint64_t target = to_us_since_boot(t);
-    uint32_t hi_target = target >> 32u;
+    uint32_t hi_target = (uint32_t)(target >> 32u);
     uint32_t hi = timer_hw->timerawh;
     return (hi >= hi_target && (timer_hw->timerawl >= (uint32_t) target || hi != hi_target));
 }
diff --git a/src/rp2_common/hardware_timer/timer.c b/src/rp2_common/hardware_timer/timer.c
index 9318a01..7745484 100644
--- a/src/rp2_common/hardware_timer/timer.c
+++ b/src/rp2_common/hardware_timer/timer.c
@@ -75,7 +75,7 @@ void busy_wait_us(uint64_t delay_us) {
 
 void busy_wait_until(absolute_time_t t) {
     uint64_t target = to_us_since_boot(t);
-    uint32_t hi_target = target >> 32u;
+    uint32_t hi_target = (uint32_t)(target >> 32u);
     uint32_t hi = timer_hw->timerawh;
     while (hi < hi_target) {
         hi = timer_hw->timerawh;
@@ -113,7 +113,7 @@ static void hardware_alarm_irq_handler(void) {
         if (timer_hw->timerawh >= target_hi[alarm_num]) {
             // we have reached the right high word as well as low word value
             callback = alarm_callbacks[alarm_num];
-            timer_callbacks_pending &= ~(1u << alarm_num);
+            timer_callbacks_pending &= (uint8_t)~(1u << alarm_num);
         } else {
             // try again in 2^32 us
             timer_hw->alarm[alarm_num] = timer_hw->alarm[alarm_num]; // re-arm the timer
@@ -147,7 +147,7 @@ void hardware_alarm_set_callback(uint alarm_num, hardware_alarm_callback_t callb
         alarm_callbacks[alarm_num] = callback;
     } else {
         alarm_callbacks[alarm_num] = NULL;
-        timer_callbacks_pending &= ~(1u << alarm_num);
+        timer_callbacks_pending &= (uint8_t)~(1u << alarm_num);
         irq_remove_handler(irq_num, hardware_alarm_irq_handler);
         irq_set_enabled(irq_num, false);
     }
@@ -167,10 +167,10 @@ bool hardware_alarm_set_target(uint alarm_num, absolute_time_t target) {
         spin_lock_t *lock = spin_lock_instance(PICO_SPINLOCK_ID_TIMER);
         uint32_t save = spin_lock_blocking(lock);
         timer_hw->intr = 1u << alarm_num;
-        timer_callbacks_pending |= 1u << alarm_num;
+        timer_callbacks_pending |= (uint8_t)(1u << alarm_num);
         timer_hw->alarm[alarm_num] = (uint32_t) t;
         // Set the alarm. Writing time should arm it
-        target_hi[alarm_num] = t >> 32u;
+        target_hi[alarm_num] = (uint32_t)(t >> 32u);
 
         // 2) check for races
         if (!(timer_hw->armed & 1u << alarm_num)) {
@@ -186,7 +186,7 @@ bool hardware_alarm_set_target(uint alarm_num, absolute_time_t target) {
                 timer_hw->armed = 1u << alarm_num;
                 timer_hw->intr = 1u << alarm_num; // clear the IRQ too
                 // and set flag in case we're already in the IRQ handler waiting on the spinlock (on the other core)
-                timer_callbacks_pending &= ~(1u << alarm_num);
+                timer_callbacks_pending &= (uint8_t)~(1u << alarm_num);
             }
         }
         spin_unlock(lock, save);
@@ -200,7 +200,7 @@ void hardware_alarm_cancel(uint alarm_num) {
     spin_lock_t *lock = spin_lock_instance(PICO_SPINLOCK_ID_TIMER);
     uint32_t save = spin_lock_blocking(lock);
     timer_hw->armed = 1u << alarm_num;
-    timer_callbacks_pending &= ~(1u << alarm_num);
+    timer_callbacks_pending &= (uint8_t)~(1u << alarm_num);
     spin_unlock(lock, save);
 }
 
diff --git a/src/rp2_common/hardware_uart/include/hardware/uart.h b/src/rp2_common/hardware_uart/include/hardware/uart.h
index 671afc7..ee84899 100644
--- a/src/rp2_common/hardware_uart/include/hardware/uart.h
+++ b/src/rp2_common/hardware_uart/include/hardware/uart.h
@@ -172,7 +172,7 @@ uint uart_set_baudrate(uart_inst_t *uart, uint baudrate);
  */
 static inline void uart_set_hw_flow(uart_inst_t *uart, bool cts, bool rts) {
     hw_write_masked(&uart_get_hw(uart)->cr,
-                   (!!cts << UART_UARTCR_CTSEN_LSB) | (!!rts << UART_UARTCR_RTSEN_LSB),
+                   (bool_to_bit(cts) << UART_UARTCR_CTSEN_LSB) | (bool_to_bit(rts) << UART_UARTCR_RTSEN_LSB),
                    UART_UARTCR_RTSEN_BITS | UART_UARTCR_CTSEN_BITS);
 }
 
@@ -191,10 +191,10 @@ static inline void uart_set_format(uart_inst_t *uart, uint data_bits, uint stop_
     invalid_params_if(UART, stop_bits != 1 && stop_bits != 2);
     invalid_params_if(UART, parity != UART_PARITY_NONE && parity != UART_PARITY_EVEN && parity != UART_PARITY_ODD);
     hw_write_masked(&uart_get_hw(uart)->lcr_h,
-                   ((data_bits - 5) << UART_UARTLCR_H_WLEN_LSB) |
-                   ((stop_bits - 1) << UART_UARTLCR_H_STP2_LSB) |
-                   ((parity != UART_PARITY_NONE) << UART_UARTLCR_H_PEN_LSB) |
-                   ((parity == UART_PARITY_EVEN) << UART_UARTLCR_H_EPS_LSB),
+                   ((data_bits - 5u) << UART_UARTLCR_H_WLEN_LSB) |
+                   ((stop_bits - 1u) << UART_UARTLCR_H_STP2_LSB) |
+                   (bool_to_bit(parity != UART_PARITY_NONE) << UART_UARTLCR_H_PEN_LSB) |
+                   (bool_to_bit(parity == UART_PARITY_EVEN) << UART_UARTLCR_H_EPS_LSB),
                    UART_UARTLCR_H_WLEN_BITS |
                    UART_UARTLCR_H_STP2_BITS |
                    UART_UARTLCR_H_PEN_BITS |
@@ -212,8 +212,8 @@ static inline void uart_set_format(uart_inst_t *uart, uint data_bits, uint stop_
  * \param tx_needs_data If true an interrupt will be fired when the TX FIFO needs data.
  */
 static inline void uart_set_irq_enables(uart_inst_t *uart, bool rx_has_data, bool tx_needs_data) {
-    uart_get_hw(uart)->imsc = (!!tx_needs_data << UART_UARTIMSC_TXIM_LSB) |
-                              (!!rx_has_data << UART_UARTIMSC_RXIM_LSB);
+    uart_get_hw(uart)->imsc = (bool_to_bit(tx_needs_data) << UART_UARTIMSC_TXIM_LSB) |
+                              (bool_to_bit(rx_has_data) << UART_UARTIMSC_RXIM_LSB);
     if (rx_has_data) {
         // Set minimum threshold
         hw_write_masked(&uart_get_hw(uart)->ifls, 0 << UART_UARTIFLS_RXIFLSEL_LSB,
@@ -244,7 +244,7 @@ static inline bool uart_is_enabled(uart_inst_t *uart) {
  */
 static inline void uart_set_fifo_enabled(uart_inst_t *uart, bool enabled) {
     hw_write_masked(&uart_get_hw(uart)->lcr_h,
-                   (!!enabled << UART_UARTLCR_H_FEN_LSB),
+                   (bool_to_bit(enabled) << UART_UARTLCR_H_FEN_LSB),
                    UART_UARTLCR_H_FEN_BITS);
 }
 
@@ -314,7 +314,7 @@ static inline void uart_read_blocking(uart_inst_t *uart, uint8_t *dst, size_t le
     for (size_t i = 0; i < len; ++i) {
         while (!uart_is_readable(uart))
             tight_loop_contents();
-        *dst++ = uart_get_hw(uart)->dr;
+        *dst++ = (uint8_t) uart_get_hw(uart)->dr;
     }
 }
 
diff --git a/src/rp2_common/hardware_vreg/vreg.c b/src/rp2_common/hardware_vreg/vreg.c
index 654ab5a..501b0d4 100644
--- a/src/rp2_common/hardware_vreg/vreg.c
+++ b/src/rp2_common/hardware_vreg/vreg.c
@@ -8,5 +8,5 @@
 #include "hardware/vreg.h"
 
 void vreg_set_voltage(enum vreg_voltage voltage) {
-    hw_write_masked(&vreg_and_chip_reset_hw->vreg, voltage << VREG_AND_CHIP_RESET_VREG_VSEL_LSB, VREG_AND_CHIP_RESET_VREG_VSEL_BITS);
+    hw_write_masked(&vreg_and_chip_reset_hw->vreg, ((uint)voltage) << VREG_AND_CHIP_RESET_VREG_VSEL_LSB, VREG_AND_CHIP_RESET_VREG_VSEL_BITS);
 }
diff --git a/src/rp2_common/pico_bootrom/include/pico/bootrom.h b/src/rp2_common/pico_bootrom/include/pico/bootrom.h
index 1300ed9..7d42926 100644
--- a/src/rp2_common/pico_bootrom/include/pico/bootrom.h
+++ b/src/rp2_common/pico_bootrom/include/pico/bootrom.h
@@ -27,8 +27,8 @@ extern "C" {
  * \param c2 the second character
  * \return the 'code' to use in rom_func_lookup() or rom_data_lookup()
  */
-static inline uint32_t rom_table_code(char c1, char c2) {
-    return (c2 << 8u) | c1;
+static inline uint32_t rom_table_code(uint8_t c1, uint8_t c2) {
+    return (((uint)c2) << 8u) | (uint)c1;
 }
 
 /*!
diff --git a/src/rp2_common/pico_double/double_math.c b/src/rp2_common/pico_double/double_math.c
index 41d4380..c6db8c1 100644
--- a/src/rp2_common/pico_double/double_math.c
+++ b/src/rp2_common/pico_double/double_math.c
@@ -9,6 +9,11 @@
 #include "pico/double.h"
 #include "pico/platform.h"
 
+// opened a separate issue https://github.com/raspberrypi/pico-sdk/issues/166 to deal with these warnings if at all
+_Pragma("GCC diagnostic push")
+_Pragma("GCC diagnostic ignored \"-Wconversion\"")
+_Pragma("GCC diagnostic ignored \"-Wsign-conversion\"")
+
 typedef uint64_t ui64;
 typedef uint32_t ui32;
 typedef int64_t i64;
@@ -40,7 +45,7 @@ _Pragma("GCC diagnostic push")
 _Pragma("GCC diagnostic ignored \"-Wstrict-aliasing\"")
 
 static inline bool disnan(double x) {
-    ui64 ix=*(i64*)&x;
+    ui64 ix=*(ui64*)&x;
     // checks the top bit of the low 32 bit of the NAN, but it I think that is ok
     return ((uint32_t)(ix >> 31)) > 0xffe00000u;
 }
@@ -604,4 +609,5 @@ double WRAPPER_FUNC(drem)(double x,double y) { check_nan_d2(x, y); return remquo
 
 double WRAPPER_FUNC(remainder)(double x,double y) { check_nan_d2(x, y); return remquo(x,y,0); }
 
-_Pragma("GCC diagnostic pop") // strict-aliasing
\ No newline at end of file
+_Pragma("GCC diagnostic pop") // strict-aliasing
+_Pragma("GCC diagnostic pop") // conversion
\ No newline at end of file
diff --git a/src/rp2_common/pico_float/float_math.c b/src/rp2_common/pico_float/float_math.c
index e54c868..bc7fa9a 100644
--- a/src/rp2_common/pico_float/float_math.c
+++ b/src/rp2_common/pico_float/float_math.c
@@ -8,11 +8,16 @@
 #include "pico/float.h"
 #include "pico/platform.h"
 
+// opened a separate issue https://github.com/raspberrypi/pico-sdk/issues/166 to deal with these warnings if at all
+_Pragma("GCC diagnostic push")
+_Pragma("GCC diagnostic ignored \"-Wconversion\"")
+_Pragma("GCC diagnostic ignored \"-Wsign-conversion\"")
+
 typedef uint32_t ui32;
 typedef int32_t i32;
 
-#define PINF ( HUGE_VAL)
-#define MINF (-HUGE_VAL)
+#define FPINF ( HUGE_VALF)
+#define FMINF (-HUGE_VALF)
 #define NANF ((float)NAN)
 #define PZERO (+0.0)
 #define MZERO (-0.0)
@@ -38,7 +43,7 @@ _Pragma("GCC diagnostic push")
 _Pragma("GCC diagnostic ignored \"-Wstrict-aliasing\"")
 
 static inline bool fisnan(float x) {
-    ui32 ix=*(i32*)&x;
+    ui32 ix=*(ui32*)&x;
     return ix * 2 > 0xff000000u;
 }
 
@@ -239,7 +244,7 @@ float WRAPPER_FUNC(asinf)(float x) {
     check_nan_f1(x);
     float u;
     u=(1.0f-x)*(1.0f+x);
-    if(fisstrictneg(u)) return fnan_or(PINF);
+    if(fisstrictneg(u)) return fnan_or(FPINF);
     return atan2f(x,sqrtf(u));
 }
 
@@ -247,7 +252,7 @@ float WRAPPER_FUNC(acosf)(float x) {
     check_nan_f1(x);
     float u;
     u=(1.0f-x)*(1.0f+x);
-    if(fisstrictneg(u)) return fnan_or(PINF);
+    if(fisstrictneg(u)) return fnan_or(FPINF);
     return atan2f(sqrtf(u),x);
 }
 
@@ -368,19 +373,19 @@ float WRAPPER_FUNC(powintf)(float x,int y) {
             if(y&1) return x;
             else    return 0;
         }
-        if((y&1)) return fcopysign(PINF,x);
-        return PINF;
+        if((y&1)) return fcopysign(FPINF,x);
+        return FPINF;
     }
     _Pragma("GCC diagnostic pop")
     check_nan_f1(x);
     if(fispinf(x)) {
         if(y<0) return 0;
-        else    return PINF;
+        else    return FPINF;
     }
     if(fisminf(x)) {
         if(y>0) {
-            if((y&1)) return MINF;
-            else      return PINF;
+            if((y&1)) return FMINF;
+            else      return FPINF;
         }
         if((y&1)) return MZERO;
         else      return PZERO;
@@ -420,31 +425,31 @@ float WRAPPER_FUNC(powf)(float x,float y) {
             if(fisoddint(y)) return x;
             else             return 0;
         }
-        if(fisoddint(y)) return fcopysign(PINF,x);
-        return PINF;
+        if(fisoddint(y)) return fcopysign(FPINF,x);
+        return FPINF;
     }
     if(fispinf(x)) {
         if(fisneg(y)) return 0;
-        else          return PINF;
+        else          return FPINF;
     }
     if(fisminf(x)) {
         if(!fisneg(y)) {
-            if(fisoddint(y)) return MINF;
-            else             return PINF;
+            if(fisoddint(y)) return FMINF;
+            else             return FPINF;
         }
         if(fisoddint(y)) return MZERO;
         else             return PZERO;
     }
     if(fispinf(y)) {
         if(fgetexp(x)<0x7f) return PZERO;
-        else                return PINF;
+        else                return FPINF;
     }
     if(fisminf(y)) {
-        if(fgetexp(x)<0x7f) return PINF;
+        if(fgetexp(x)<0x7f) return FPINF;
         else                return PZERO;
     }
     if(fisint(y)) return fpow_0(x,y);
-    if(fisneg(x)) return PINF;
+    if(fisneg(x)) return FPINF;
     return fpow_1(x,y);
 }
 
@@ -506,9 +511,9 @@ float WRAPPER_FUNC(fmodf)(float x,float y) {
     FUNPACKS(ix,sx,ex,mx);
     FUNPACK(iy,ey,my);
     if(ex==0xff) {
-        return fnan_or(PINF);
+        return fnan_or(FPINF);
     }
-    if(ey==0) return PINF;
+    if(ey==0) return FPINF;
     if(ex==0) {
         if(!fisneg(x)) return PZERO;
         return MZERO;
@@ -527,8 +532,8 @@ float WRAPPER_FUNC(remquof)(float x,float y,int*quo) {
     FUNPACKS(ix,sx,ex,mx);
     FUNPACKS(iy,sy,ey,my);
     if(quo) *quo=0;
-    if(ex==0xff) return PINF;
-    if(ey==0)    return PINF;
+    if(ex==0xff) return FPINF;
+    if(ey==0)    return FPINF;
     if(ex==0)    return PZERO;
     if(ey==0xff) return x;
     if(ex<ey-1)  return x;  // |x|<|y|/2
@@ -563,3 +568,4 @@ float WRAPPER_FUNC(dremf)(float x,float y) { check_nan_f2(x,y); return remquof(x
 float WRAPPER_FUNC(remainderf)(float x,float y) { check_nan_f2(x,y); return remquof(x,y,0); }
 
 _Pragma("GCC diagnostic pop") // strict-aliasing
+_Pragma("GCC diagnostic pop") // conversion
\ No newline at end of file
diff --git a/src/rp2_common/pico_malloc/pico_malloc.c b/src/rp2_common/pico_malloc/pico_malloc.c
index 2842a85..4928a8e 100644
--- a/src/rp2_common/pico_malloc/pico_malloc.c
+++ b/src/rp2_common/pico_malloc/pico_malloc.c
@@ -20,7 +20,7 @@ extern void __real_free(void *mem);
 
 extern char __StackLimit; /* Set by linker.  */
 
-static inline void check_alloc(__unused void *mem, __unused uint8_t size) {
+static inline void check_alloc(__unused void *mem, __unused uint size) {
 #if PICO_MALLOC_PANIC
     if (!mem || (((char *)mem) + size) > &__StackLimit) {
         panic("Out of memory");
diff --git a/src/rp2_common/pico_multicore/include/pico/multicore.h b/src/rp2_common/pico_multicore/include/pico/multicore.h
index 8179b73..9ecc146 100644
--- a/src/rp2_common/pico_multicore/include/pico/multicore.h
+++ b/src/rp2_common/pico_multicore/include/pico/multicore.h
@@ -153,7 +153,7 @@ static inline void multicore_fifo_clear_irq(void) {
  * 1 | Value is 1 if this core’s TX FIFO is not full (i.e. if FIFO_WR is ready for more data)
  * 0 | Value is 1 if this core’s RX FIFO is not empty (i.e. if FIFO_RD is valid)
 */
-static inline int32_t multicore_fifo_get_status(void) {
+static inline uint32_t multicore_fifo_get_status(void) {
     return sio_hw->fifo_st;
 }
 
diff --git a/src/rp2_common/pico_multicore/multicore.c b/src/rp2_common/pico_multicore/multicore.c
index cd57800..fa4f49e 100644
--- a/src/rp2_common/pico_multicore/multicore.c
+++ b/src/rp2_common/pico_multicore/multicore.c
@@ -204,13 +204,13 @@ static bool multicore_lockout_handshake(uint32_t magic, absolute_time_t until) {
         if (next_timeout_us < 0) {
             break;
         }
-        multicore_fifo_push_timeout_us(magic, next_timeout_us);
+        multicore_fifo_push_timeout_us(magic, (uint64_t)next_timeout_us);
         next_timeout_us = absolute_time_diff_us(get_absolute_time(), until);
         if (next_timeout_us < 0) {
             break;
         }
         uint32_t word = 0;
-        if (!multicore_fifo_pop_timeout_us(next_timeout_us, &word)) {
+        if (!multicore_fifo_pop_timeout_us((uint64_t)next_timeout_us, &word)) {
             break;
         }
         if (word == magic) {
diff --git a/src/rp2_common/pico_platform/platform.c b/src/rp2_common/pico_platform/platform.c
index 293ec27..9bbcf26 100644
--- a/src/rp2_common/pico_platform/platform.c
+++ b/src/rp2_common/pico_platform/platform.c
@@ -34,6 +34,6 @@ uint8_t rp2040_chip_version() {
     assert(manufacturer == MANUFACTURER_RPI);
     assert(part == PART_RP2);
     // Version 1 == B0/B1
-    int version = (chip_id & SYSINFO_CHIP_ID_REVISION_BITS) >> SYSINFO_CHIP_ID_REVISION_LSB;
-    return version;
+    uint version = (chip_id & SYSINFO_CHIP_ID_REVISION_BITS) >> SYSINFO_CHIP_ID_REVISION_LSB;
+    return (uint8_t)version;
 }
\ No newline at end of file
diff --git a/src/rp2_common/pico_printf/printf.c b/src/rp2_common/pico_printf/printf.c
index 833bd7f..fde2980 100644
--- a/src/rp2_common/pico_printf/printf.c
+++ b/src/rp2_common/pico_printf/printf.c
@@ -290,7 +290,7 @@ static size_t _ntoa_long(out_fct_type out, char *buffer, size_t idx, size_t maxl
     if (!(flags & FLAGS_PRECISION) || value) {
         do {
             const char digit = (char) (value % base);
-            buf[len++] = digit < 10 ? '0' + digit : (flags & FLAGS_UPPERCASE ? 'A' : 'a') + digit - 10;
+            buf[len++] = (char)(digit < 10 ? '0' + digit : (flags & FLAGS_UPPERCASE ? 'A' : 'a') + digit - 10);
             value /= base;
         } while (value && (len < PICO_PRINTF_NTOA_BUFFER_SIZE));
     }
@@ -317,7 +317,7 @@ static size_t _ntoa_long_long(out_fct_type out, char *buffer, size_t idx, size_t
     if (!(flags & FLAGS_PRECISION) || value) {
         do {
             const char digit = (char) (value % base);
-            buf[len++] = digit < 10 ? '0' + digit : (flags & FLAGS_UPPERCASE ? 'A' : 'a') + digit - 10;
+            buf[len++] = (char)(digit < 10 ? '0' + digit : (flags & FLAGS_UPPERCASE ? 'A' : 'a') + digit - 10);
             value /= base;
         } while (value && (len < PICO_PRINTF_NTOA_BUFFER_SIZE));
     }
@@ -559,7 +559,7 @@ static size_t _etoa(out_fct_type out, char *buffer, size_t idx, size_t maxlen, d
         // output the exponential symbol
         out((flags & FLAGS_UPPERCASE) ? 'E' : 'e', buffer, idx++, maxlen);
         // output the exponent value
-        idx = _ntoa_long(out, buffer, idx, maxlen, (expval < 0) ? -expval : expval, expval < 0, 10, 0, minwidth - 1,
+        idx = _ntoa_long(out, buffer, idx, maxlen, (uint)((expval < 0) ? -expval : expval), expval < 0, 10, 0, minwidth - 1,
                          FLAGS_ZEROPAD | FLAGS_PLUS);
         // might need to right-pad spaces
         if (flags & FLAGS_LEFT) {
diff --git a/src/rp2_common/pico_runtime/runtime.c b/src/rp2_common/pico_runtime/runtime.c
index 79e6290..c6a5830 100644
--- a/src/rp2_common/pico_runtime/runtime.c
+++ b/src/rp2_common/pico_runtime/runtime.c
@@ -52,7 +52,7 @@ void runtime_install_stack_guard(void *stack_bottom) {
     // mask is 1 bit per 32 bytes of the 256 byte range... clear the bit for the segment we want
     uint32_t subregion_select = 0xffu ^ (1u << ((addr >> 5u) & 7u));
     mpu_hw->ctrl = 5; // enable mpu with background default map
-    mpu_hw->rbar = (addr & ~0xff) | 0x8 | 0;
+    mpu_hw->rbar = (addr & (uint)~0xff) | 0x8 | 0;
     mpu_hw->rasr = 1 // enable region
                    | (0x7 << 1) // size 2^(7 + 1) = 256
                    | (subregion_select << 8)
@@ -120,7 +120,7 @@ void runtime_init(void) {
 
 #if !(PICO_NO_RAM_VECTOR_TABLE || PICO_NO_FLASH)
     __builtin_memcpy(ram_vector_table, (uint32_t *) scb_hw->vtor, sizeof(ram_vector_table));
-    scb_hw->vtor = (intptr_t) ram_vector_table;
+    scb_hw->vtor = (uintptr_t) ram_vector_table;
 #endif
 
 #ifndef NDEBUG
diff --git a/src/rp2_common/pico_standard_link/binary_info.c b/src/rp2_common/pico_standard_link/binary_info.c
index 6559b06..ba5dad8 100644
--- a/src/rp2_common/pico_standard_link/binary_info.c
+++ b/src/rp2_common/pico_standard_link/binary_info.c
@@ -15,7 +15,7 @@
 #if !PICO_NO_FLASH
 #ifndef PICO_NO_BI_BINARY_SIZE
 extern char __flash_binary_end;
-bi_decl_with_attr(bi_binary_end((uintptr_t)&__flash_binary_end), reset_section_attr)
+bi_decl_with_attr(bi_binary_end((intptr_t)&__flash_binary_end), reset_section_attr)
 #endif
 #endif
 
diff --git a/src/rp2_common/pico_stdio/stdio.c b/src/rp2_common/pico_stdio/stdio.c
index da2755d..074f288 100644
--- a/src/rp2_common/pico_stdio/stdio.c
+++ b/src/rp2_common/pico_stdio/stdio.c
@@ -94,7 +94,7 @@ static bool stdio_put_string(const char *s, int len, bool newline) {
         return false;
 #endif
     }
-    if (len == -1) len = strlen(s);
+    if (len == -1) len = (int)strlen(s);
     for (stdio_driver_t *driver = drivers; driver; driver = driver->next) {
         if (!driver->out_chars) continue;
         if (filter && filter != driver) continue;
@@ -129,13 +129,13 @@ static int stdio_get_until(char *buf, int len, absolute_time_t until) {
 }
 
 int WRAPPER_FUNC(putchar)(int c) {
-    char cc = c;
+    char cc = (char)c;
     stdio_put_string(&cc, 1, false);
     return c;
 }
 
 int WRAPPER_FUNC(puts)(const char *s) {
-    int len = strlen(s);
+    int len = (int)strlen(s);
     stdio_put_string(s, len, true);
     stdio_flush();
     return len;
@@ -181,7 +181,7 @@ void stdio_flush() {
 }
 
 typedef struct stdio_stack_buffer {
-    uint used;
+    int used;
     char buf[PICO_STDIO_STACK_BUFFER_SIZE];
 } stdio_stack_buffer_t;
 
diff --git a/src/rp2_common/pico_stdio_uart/stdio_uart.c b/src/rp2_common/pico_stdio_uart/stdio_uart.c
index 47bb91c..d5767a7 100644
--- a/src/rp2_common/pico_stdio_uart/stdio_uart.c
+++ b/src/rp2_common/pico_stdio_uart/stdio_uart.c
@@ -69,8 +69,8 @@ void stdin_uart_init() {
 void stdio_uart_init_full(struct uart_inst *uart, uint baud_rate, int tx_pin, int rx_pin) {
     uart_instance = uart;
     uart_init(uart_instance, baud_rate);
-    if (tx_pin != -1) gpio_set_function(tx_pin, GPIO_FUNC_UART);
-    if (rx_pin != -1) gpio_set_function(rx_pin, GPIO_FUNC_UART);
+    if (tx_pin >= 0) gpio_set_function((uint)tx_pin, GPIO_FUNC_UART);
+    if (rx_pin >= 0) gpio_set_function((uint)rx_pin, GPIO_FUNC_UART);
     stdio_set_driver_enabled(&stdio_uart, true);
 }
 
diff --git a/test/kitchen_sink/CMakeLists.txt b/test/kitchen_sink/CMakeLists.txt
index 2e522dd..2976f76 100644
--- a/test/kitchen_sink/CMakeLists.txt
+++ b/test/kitchen_sink/CMakeLists.txt
@@ -65,13 +65,12 @@ target_compile_options(kitchen_sink_options INTERFACE
         -Wcast-qual
         -Wfloat-equal
         -Wmissing-format-attribute
+        -Wconversion
         $<$<COMPILE_LANGUAGE:C>:-Wstrict-prototypes>
 
         -Wno-inline
         # todo not sure these are true, but investigate
         #-Wpacked
-        # todo requires unsigned register constants
-        #-Wconversion
 
         # todo we have some of these in usb_device_tiny to try to make it more readable.. perhaps doxygen would help here instead
         -Wredundant-decls