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authorjaseg <git@jaseg.de>2021-03-24 17:46:22 +0100
committerjaseg <git@jaseg.de>2021-03-24 17:46:22 +0100
commit6fc8f236916c10811b8611f46edea4f3be2118b3 (patch)
tree558fc394ab24930518040ffdd778c3a3ed60d38e /prototype/fw
parentc67f7d626b76238e561304b53f31afdad7e2f671 (diff)
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Add sigrok frequency meter
Diffstat (limited to 'prototype/fw')
-rw-r--r--prototype/fw/freqmeter.py71
1 files changed, 71 insertions, 0 deletions
diff --git a/prototype/fw/freqmeter.py b/prototype/fw/freqmeter.py
new file mode 100644
index 0000000..54c1655
--- /dev/null
+++ b/prototype/fw/freqmeter.py
@@ -0,0 +1,71 @@
+#!/usr/bin/env python3
+
+import csv
+import subprocess
+import io
+import itertools
+import warnings
+import statistics
+import time
+
+count = lambda le_iter: sum(1 for _ in le_iter)
+
+DEFAULT_SAMPLING_RATE = 1e6 # sps
+
+def sigrok_capture(duration:'seconds'=1, sampling_rate=DEFAULT_SAMPLING_RATE, driver='dreamsourcelab-dslogic', config=None, channel=0):
+
+ proc = subprocess.run(['sigrok-cli',
+ '--driver', driver,
+ '--time', f'{duration}s',
+ '--config', (f'{config},' if config else '') + f'samplerate={int(sampling_rate/1e3)}k',
+ '--channels', str(channel),
+ '--output-format', 'csv'], check=True, stdout=subprocess.PIPE)
+
+ lines = proc.stdout.splitlines()
+ return lines[lines.index(b'logic')+1:]
+
+def debounce(lines, sampling_rate=DEFAULT_SAMPLING_RATE, debounce_interval=1e-3):
+ debounce_len = debounce_interval * sampling_rate
+
+ cumline = None
+ cumsum = None
+ for line, group in itertools.groupby(lines):
+ group_len = count(group)
+
+ if cumline is None:
+ cumline, cumsum = line, group_len
+
+ if group_len < debounce_len:
+ cumsum += group_len
+
+ else:
+ yield bool(int(cumline.decode())), cumsum
+ cumline, cumsum = line, group_len
+
+ yield bool(int(cumline.decode())), cumsum
+
+def calc_frequency(intervals, sampling_rate=DEFAULT_SAMPLING_RATE):
+ # make sure intervals alternate true/false
+ if not all( a != b for a, b in zip(intervals[0::2], intervals[1::2])):
+ raise ValueError('Intervals do not alternate!')
+
+ sums = [ DEFAULT_SAMPLING_RATE / (a[1] + b[1]) for a, b in zip(intervals[0::2], intervals[1::2]) ]
+ return statistics.mean(sums), statistics.stdev(sums)
+
+if __name__ == '__main__':
+ while True:
+ capture = sigrok_capture()
+ intervals = list(debounce(capture))
+
+ intervals = intervals[2:-1] # ignore partial first and last intervals
+
+ # Ignore last interval if we have an uneven number of intervals
+ if intervals[-1] == intervals[0]:
+ intervals = intervals[:-1]
+
+ try:
+ mean, stdev = calc_frequency(intervals)
+ print(f'\033[38;5;244m{time.strftime("%H:%M:%S")} \033[93m{mean*1e3:> 9.3f} \033[38;5;244m± {stdev*1e3:> 8.3f} mHz\033[0m')
+ except ValueError as e:
+ warnings.warn(*e.args)
+