diff options
Diffstat (limited to 'controller/fw/tools')
| -rw-r--r-- | controller/fw/tools/butter_filter_gen.py | 35 |
1 files changed, 32 insertions, 3 deletions
diff --git a/controller/fw/tools/butter_filter_gen.py b/controller/fw/tools/butter_filter_gen.py index c77a6ec..0bb81bc 100644 --- a/controller/fw/tools/butter_filter_gen.py +++ b/controller/fw/tools/butter_filter_gen.py @@ -18,11 +18,21 @@ def wrap(left='{', right='}', file=None, end=''): def print_include_guards(macro_name): print(f'#ifndef {macro_name}') print(f'#define {macro_name}') + print() yield + print() print(f'#endif /* {macro_name} */') macro_float = lambda f: f'{f}'.replace('.', 'F').replace('-', 'N').replace('+', 'P') +ordinal = lambda n: "%d%s" % (n,"tsnrhtdd"[(n//10%10!=1)*(n%10<4)*n%10::4]) + +SI_TABLE = {-18: 'a', -15: 'f', -12: 'p', -9: 'n', -6: 'ยต', -3: 'm', 0: '', 3: 'k', 6: 'M', 9: 'G', 12: 'T', 15: 'P', 18: 'E'} +def siprefix(x, space=' ', unit=''): + l = math.log10(x)//3*3 + if l in SI_TABLE: + return f'{x/10**l}{space}{SI_TABLE[l]}{unit}' + return f'{x}{space}{unit}' if __name__ == '__main__': import argparse @@ -36,10 +46,17 @@ if __name__ == '__main__': sos = sig.butter(args.n, args.fc, fs=args.fs, output='sos') print('/* THIS IS A GENERATED FILE. DO NOT EDIT! */') + print() with print_include_guards(f'__BUTTER_FILTER_GENERATED_{args.n}_{macro_float(args.fc)}_{macro_float(args.fs)}__'): + + print(f'/* {ordinal(args.n)} order Butterworth IIR filter coefficients') + print(f' *') + print(f' * corner frequency f_c = {siprefix(args.fc)}Hz') + print(f' * sampling rate f_s = {siprefix(args.fs)}Hz') + print(f' */') + print() 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='') # 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. @@ -48,10 +65,14 @@ if __name__ == '__main__': mags = [approx_mag // len(sos)] * len(sos) mags[0] += approx_mag - sum(mags) sos[0][:3] /= 10**approx_mag + sos = np.array([ sec * np.array([10**mag, 10**mag, 10**mag, 1, 1, 1]) for mag, sec in zip(mags, sos) ]) + + ones = np.ones([100000]) + _, steady_state = sig.sosfilt(sos, ones, zi=np.zeros([(args.n+1)//2, 2])) - for mag, sec in zip(mags, sos): + print(f'#define {args.macro_name.upper()}_COEFF ', end='') + for sec in sos: bs, ases = sec[:3], sec[4:6] - bs *= 10**mag with wrap(): print('.b=', end='') @@ -62,3 +83,11 @@ if __name__ == '__main__': print(', '.join(f'{v}' for v in ases), end='') print(', ', end='') print() + + print(f'#define {args.macro_name.upper()}_STEADY_STATE ', end='') + for sec in steady_state: + with wrap(): + print(', '.join(f'{v}' for v in sec), end='') + print(', ', end='') + print() + |