From ffcdeecfc9afc512c21077b7d48a3130474eebd0 Mon Sep 17 00:00:00 2001
From: Andreas Gattringer <andreas.gattringer@univie.ac.at>
Date: Wed, 31 Jul 2024 16:07:58 +0200
Subject: [PATCH] dmatest: vary sampling frequency based on signal processing
---
programs/dmatest_v2.py | 36 +++++++++++++++++++++++++++++-------
1 file changed, 29 insertions(+), 7 deletions(-)
diff --git a/programs/dmatest_v2.py b/programs/dmatest_v2.py
index d0b83a5..56d0afe 100644
--- a/programs/dmatest_v2.py
+++ b/programs/dmatest_v2.py
@@ -3,14 +3,12 @@
# which is Copyright (c) 2021 Jeremy P Bentham and licensed under the Apache License, Version 2.0
import array
-import math
+import asyncio
+import gc
-import machine
import rp2
-import asyncio
import uctypes
from uctypes import BF_POS, BF_LEN, UINT32, BFUINT32, struct
-import gc
ADC_BASE = 0x4004C000
@@ -61,7 +59,8 @@ def t(x):
SAMPLES = 1000
SAMPLING_RATE_HZ = 22000
-
+SAMPLING_FREQ_TO_HIGH = -2
+SAMPLING_FREQ_TO_LOW = -1
class AdcDevice:
def __init__(self, device_nr, rate=SAMPLING_RATE_HZ, samples=SAMPLES):
@@ -92,6 +91,9 @@ class AdcDevice:
self._rate = rate
self.__adc_device.DIV_REG = (48000000 // self._rate - 1) << 8
+ def get_sampling_rate(self):
+ return self._rate
+
def set_sample_count(self, samples):
async with self.__lock:
self._sample_count = samples
@@ -191,10 +193,13 @@ def calculate_frequency(voltages_centered, sampling_rate):
consecutive_sign += 1
if len(counts) < 3:
- return -1
+ return SAMPLING_FREQ_TO_HIGH
counts = counts[1:-1]
- f = sampling_rate / (2 * sum(counts) / len(counts))
+ count_mean = sum(counts) / len(counts)
+ if count_mean < 5:
+ return SAMPLING_FREQ_TO_LOW
+ f = sampling_rate / (2 * count_meant)
count = None
return f
@@ -239,6 +244,23 @@ async def main():
voltage_mean = sum(voltages) / SAMPLES
voltages_centered = [v - voltage_mean for v in voltages]
freq = calculate_frequency(voltages_centered, sampling_rate=SAMPLING_RATE_HZ)
+ if freq == SAMPLING_FREQ_TO_HIGH:
+ rate = device.get_sampling_rate()
+ if rate < 3:
+ print(f"Cannot reduce sampling frequency rate further than {rate}")
+ continue
+ device.set_sampling_rate(rate / 2.0)
+ print(f"Reducing sampling rate to {device.get_sampling_rate()}")
+ continue
+ elif freq == SAMPLING_FREQ_TO_LOW:
+ rate = device.get_sampling_rate()
+ if rate > 100000:
+ print(f"Cannot reduce increase frequency rate further than {rate}")
+ continue
+ device.set_sampling_rate(rate * 2)
+ print(f"Increasing sampling rate to {device.get_sampling_rate()}")
+ continue
+
v_to_v = calculate_peak_to_peak(voltages_centered)
print(f"{freq:0.2f} Hz, {v_to_v:0.2f} V peak to peak")
gc.collect()
--
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