From 24bb3627cf59b13098042c5e1299cb5cbfa9b6cc Mon Sep 17 00:00:00 2001 From: alastairpatrick Date: Wed, 5 Oct 2022 17:06:26 -0700 Subject: [PATCH] PLL REFDIV values > 1 considered by vcocalc.py (#952) --- .../hardware_clocks/scripts/vcocalc.py | 36 +++++++++++-------- 1 file changed, 22 insertions(+), 14 deletions(-) diff --git a/src/rp2_common/hardware_clocks/scripts/vcocalc.py b/src/rp2_common/hardware_clocks/scripts/vcocalc.py index 5d143b3..69f4d02 100755 --- a/src/rp2_common/hardware_clocks/scripts/vcocalc.py +++ b/src/rp2_common/hardware_clocks/scripts/vcocalc.py @@ -4,6 +4,7 @@ import argparse parser = argparse.ArgumentParser(description="PLL parameter calculator") parser.add_argument("--input", "-i", default=12, help="Input (reference) frequency. Default 12 MHz", type=float) +parser.add_argument("--ref-min", default=5, help="Override minimum reference frequency. Default 5 MHz", type=float) parser.add_argument("--vco-max", default=1600, help="Override maximum VCO frequency. Default 1600 MHz", type=float) parser.add_argument("--vco-min", default=750, help="Override minimum VCO frequency. Default 750 MHz", type=float) parser.add_argument("--low-vco", "-l", action="store_true", help="Use a lower VCO frequency when possible. This reduces power consumption, at the cost of increased jitter") @@ -13,25 +14,32 @@ args = parser.parse_args() # Fixed hardware parameters fbdiv_range = range(16, 320 + 1) postdiv_range = range(1, 7 + 1) +ref_min = 5 +refdiv_min = 1 +refdiv_max = 63 -best = (0, 0, 0, 0) +refdiv_range = range(refdiv_min, max(refdiv_min, min(refdiv_max, int(args.input / args.ref_min))) + 1) + +best = (0, 0, 0, 0, 0) best_margin = args.output -for fbdiv in (fbdiv_range if args.low_vco else reversed(fbdiv_range)): - vco = args.input * fbdiv - if vco < args.vco_min or vco > args.vco_max: - continue - # pd1 is inner loop so that we prefer higher ratios of pd1:pd2 - for pd2 in postdiv_range: - for pd1 in postdiv_range: - out = vco / pd1 / pd2 - margin = abs(out - args.output) - if margin < best_margin: - best = (out, fbdiv, pd1, pd2) - best_margin = margin +for refdiv in refdiv_range: + for fbdiv in (fbdiv_range if args.low_vco else reversed(fbdiv_range)): + vco = args.input / refdiv * fbdiv + if vco < args.vco_min or vco > args.vco_max: + continue + # pd1 is inner loop so that we prefer higher ratios of pd1:pd2 + for pd2 in postdiv_range: + for pd1 in postdiv_range: + out = vco / pd1 / pd2 + margin = abs(out - args.output) + if margin < best_margin: + best = (out, fbdiv, pd1, pd2, refdiv) + best_margin = margin print("Requested: {} MHz".format(args.output)) print("Achieved: {} MHz".format(best[0])) -print("FBDIV: {} (VCO = {} MHz)".format(best[1], args.input * best[1])) +print("REFDIV: {}".format(best[4])) +print("FBDIV: {} (VCO = {} MHz)".format(best[1], args.input / best[4] * best[1])) print("PD1: {}".format(best[2])) print("PD2: {}".format(best[3]))