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I have an I2C device with address 0x62. I know this because I plugged it into my RPI 4B and ran sudo i2cdetect -y 1. I see the device, if I remove the device power and rerun the command, the device is missing from the list.

I am trying to write a circuitpython script to interface with this device. My code is very simple

import busio
from board import *

i2c = busio.I2C(SCL, SDA)
print(i2c.scan())
i2c.deinit()

This always returns an empty list. I can not figure out why. When I run sudo i2cget -y 1 0x62 I get the error Error: Read failed. I have tired a few different versions of the code above. I have tried to use while i2c.trylock(), no change.

Adafruit has the following code:

"""CircuitPython Essentials I2C Scan example"""
# If you run this and it seems to hang, try manually unlocking
# your I2C bus from the REPL with
#  >>> import board
#  >>> board.I2C().unlock()

import time
import board


i2c = board.I2C()


while not i2c.try_lock():
    pass


try:
    while True:
        print("I2C addresses found:", [hex(device_address)
              for device_address in i2c.scan()])
        time.sleep(2)


finally:  # unlock the i2c bus when ctrl-c'ing out of the loop
    i2c.unlock()

This also fails to find my device.

Device is SCD41 CO2 Sensor. I have a small dev kit for it which provides pinout.

I can not attach the image so I am sharing a link to it. Yellow is SCL and attached to pin 5, Green is SDA and is attached to pin 3.

cigien
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Michael Miner
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1 Answers1

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So Adafruit makes a dev board with this part on it already. As such they also have a very public very useful github repo.

Using this I can now communicate with the device, exploring the rest of the repo I see how one can use the underlying I2C code to create their own objects. This is helpful for the project I am working on in which I have to interface with an I2C controllable ADC.

SCD41 CO2 Sensor

Michael Miner
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