diff options
Diffstat (limited to 'controller/fw/tools')
| -rw-r--r-- | controller/fw/tools/butter_filter_gen.py | 20 |
1 files changed, 17 insertions, 3 deletions
diff --git a/controller/fw/tools/butter_filter_gen.py b/controller/fw/tools/butter_filter_gen.py index 059dea0..c77a6ec 100644 --- a/controller/fw/tools/butter_filter_gen.py +++ b/controller/fw/tools/butter_filter_gen.py @@ -1,9 +1,11 @@ #!/usr/bin/env python3 +import math import sys import contextlib import scipy.signal as sig +import numpy as np @contextlib.contextmanager @@ -38,13 +40,25 @@ if __name__ == '__main__': print(f'#define {args.macro_name.upper()}_ORDER {args.n}') print(f'#define {args.macro_name.upper()}_CLEN {(args.n+1)//2}') print(f'#define {args.macro_name.upper()}_COEFF ', end='') - for sec in sos: + + # scipy.signal.butter by default returns extremely small bs for the first biquad and large ones for subsequent + # sections. Balance magnitudes to reduce possible rounding errors. + first_biquad_bs = sos[0][:3] + approx_mag = round(math.log10(np.mean(first_biquad_bs))) + mags = [approx_mag // len(sos)] * len(sos) + mags[0] += approx_mag - sum(mags) + sos[0][:3] /= 10**approx_mag + + for mag, sec in zip(mags, sos): + bs, ases = sec[:3], sec[4:6] + bs *= 10**mag + with wrap(): print('.b=', end='') with wrap(): - print(', '.join(f'{v}' for v in sec[:3]), end='') + print(', '.join(f'{v}' for v in bs), end='') print(', .a=', end='') with wrap(): - print(', '.join(f'{v}' for v in sec[4:6]), end='') + print(', '.join(f'{v}' for v in ases), end='') print(', ', end='') print() |