Raspberry Pi Pico ADC changes the sampling rate in Free-running Sampling mode
Port, board and/or hardware
Raspberry Pi Pico
MicroPython version
MicroPython v1.23.0 ,RPI_PICO-20240602-v1.23.0
Reproduction
def configure_adc_sample_rate(self, sample_rate):
"""
Configure the ADC sampling rate. Due to unknown reasons, the DIV register cannot be configured here. The actual sampling period is fixed at 65
:param sample_rate: Desired sample rate (Hz)
:return: None
"""
# Ensure that the sampling rate is within a reasonable range
if sample_rate <= 0 or sample_rate > 48_000_000:
raise ValueError("sample rate out of range")
# Calculate divider value
total_period = 48_000_000 / sample_rate
int_part = int(total_period) - 1
frac_part = int((total_period - int_part - 1) * 256)
div_value = mem32[DMA_ADC_Transfer.DIV_REG]
# Write the sampling period to the DIV register
mem32[DMA_ADC_Transfer.DIV_REG] = div_value | (int_part << 8) | frac_part
Expected behaviour
I am configuring the ADC sampling rate here. Due to unknown reasons, the DIV register cannot be configured here. The actual sampling period is fixed at 65.
Can anyone help me what is going wrong here？
Observed behaviour
(base) PS D:\lee\windows terminal\terminal-1.17.11461.0> mpremote connect COM8
Connected to MicroPython at COM8
Use Ctrl-] or Ctrl-x to exit this shell
div_value = mem32[DMA_ADC_Transfer.DIV_REG]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'mem32' isn't defined
from machine import mem32
div_value = mem32[DMA_ADC_Transfer.DIV_REG]
div_value
12582656
total_period = 48_000_000 / 48000
total_period = 48_000_000 / 480000
total_period
100.0
int_part = int(total_period) - 1
frac_part = int((total_period - int_part - 1) * 256)
mem32[DMA_ADC_Transfer.DIV_REG] = div_value | (int_part << 8) | frac_part
mem32[DMA_ADC_Transfer.DIV_REG]
12582656
total_period = 48_000_000 / 480000
int_part = int(total_period) - 1
frac_part = int((total_period - int_part - 1) * 256)
mem32[DMA_ADC_Transfer.DIV_REG] = div_value | (int_part << 8) | frac_part
mem32[DMA_ADC_Transfer.DIV_REG]
12582656
Additional Information
<img width="554" alt="a91a38f1944c012e122d14c44dcbc40" src="https://github.com/user-attachments/assets/bf2fc3ad-9186-4a46-82b2-0262dbcb828a">
Code of Conduct
Yes, I agree
TypeError: can't convert float to int
Port, board and/or hardware
rp2, Pico W
MicroPython version
Version: MicroPython v1.23.0 on 2024-06-02; Raspberry Pi Pico W with RP2040
This works:
Timer(-1, mode=Timer.PERIODIC, period=1000, callback=lambda _: led.toggle())
But this doesn't:
Timer(-1, mode=Timer.PERIODIC, period=1000.0, callback=lambda _: led.toggle())
Error:
TypeError: can't convert float to int
Surprised me a lot, is this intended behaviour?
Cheers
Reproduction
from machine import *
led = Pin("LED", Pin.OUT)
# Some arguments are only accepted as integers! That's surprising
timer = Timer(-1, mode=Timer.PERIODIC, period=1000.0, callback=lambda _: led.toggle())
Expected behaviour
No response
Observed behaviour
Fails with: TypeError: can't convert float to int
Additional Information
No, I've provided everything above.
Code of Conduct
Yes, I agree