PCA9685 found in i2cdetect but throws [Errno 121] Remote I/O error

We’re trying a new devkit board for jetson nano (production edition): https://www.leopardimaging.com/product/nvidia-jetson-cameras/nvidia_nano_mipi_camera_kits/li-nano-cb/li-nano-cb/

It has an I2C header, we can see the address 40 in i2cdetect, but it throws errors in python:

WARNING: Carrier board is not from a Jetson Developer Kit.
WARNNIG: Jetson.GPIO library has not been verified with this carrier board,
WARNING: and in fact is unlikely to work correctly.
Traceback (most recent call last):
  File "/home/jetson/.local/lib/python3.8/site-packages/adafruit_bus_device/i2c_device.py", line 172, in __probe_for_device
    self.i2c.writeto(self.device_address, b"")
  File "/home/jetson/.local/lib/python3.8/site-packages/busio.py", line 116, in writeto
    return self._i2c.writeto(address, buffer, stop=stop)
  File "/home/jetson/.local/lib/python3.8/site-packages/adafruit_blinka/microcontroller/generic_linux/i2c.py", line 49, in writeto
    self._i2c_bus.write_bytes(address, buffer[start:end])
  File "/home/jetson/.local/lib/python3.8/site-packages/Adafruit_PureIO/smbus.py", line 308, in write_bytes
    self._device.write(buf)
OSError: [Errno 121] Remote I/O error

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/jetson/.local/lib/python3.8/site-packages/adafruit_bus_device/i2c_device.py", line 178, in __probe_for_device
    self.i2c.readfrom_into(self.device_address, result)
  File "/home/jetson/.local/lib/python3.8/site-packages/busio.py", line 106, in readfrom_into
    return self._i2c.readfrom_into(address, buffer, stop=stop)
  File "/home/jetson/.local/lib/python3.8/site-packages/adafruit_blinka/microcontroller/generic_linux/i2c.py", line 56, in readfrom_into
    readin = self._i2c_bus.read_bytes(address, end - start)
  File "/home/jetson/.local/lib/python3.8/site-packages/Adafruit_PureIO/smbus.py", line 179, in read_bytes
    return self._device.read(number)
OSError: [Errno 121] Remote I/O error

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "gst.py", line 30, in <module>
    pca = PCA9685(i2c, address = 0x40)
  File "/home/jetson/.local/lib/python3.8/site-packages/adafruit_pca9685.py", line 137, in _init_
    self.i2c_device = i2c_device.I2CDevice(i2c_bus, address)
  File "/home/jetson/.local/lib/python3.8/site-packages/adafruit_bus_device/i2c_device.py", line 68, in _init_
    self.__probe_for_device()
  File "/home/jetson/.local/lib/python3.8/site-packages/adafruit_bus_device/i2c_device.py", line 180, in __probe_for_device
    raise ValueError("No I2C device at address: %x" % self.device_address)
ValueError: No I2C device at address: 40
Exiting...
Cleaning up pins

Our code:

from board import SCL, SDA
import busio
from adafruit_pca9685 import PCA9685

from adafruit_motor import servo
i2c = busio.I2C(SCL, SDA)
pca = PCA9685(i2c, address = 0x40)

We understand it’s a custom board, but can you please at least point us in the right direction?

Thank you! R

[razvanphp]

hey, thanks for the hint, worked like this:

from board import SCL_1, SDA_1
import busio
from adafruit_pca9685 import PCA9685

from adafruit_motor import servo
i2c = busio.I2C(SCL_1, SDA_1)
pca = PCA9685(i2c, address = 0x40)

[ladyada]

yeah it sounds liek you have an i2c pinout issue. check you ahve the right i2c device