Pi3+, IO+ and OSError: [Errno 121] Remote I/O error
The IO Pi Plus is a 32 channel MCP23017 GPIO expander for the Raspberry Pi
14/12/2021
Posted by:
cncman
Hi,
I have Pi3+, Debian Bullseye 64bit and IO+ board which works for some time but aborts with "OSError: [Errno 121] Remote I/O error", no matter what I have tried to tune config.txt.
There is RTC clock connected (from Aliexpress but they seem to be all similar), pigpio daemon running for encoder (currently disconnected), and pyfirmata to control step motors via USB and Arduino Due/AccelStepper.
Current parameters:
This error occurs quite shortly, even without sending any data via Firmata to Arduino, and PIGPIO just running idle. IO+ is connected to 8-relay board and ena/dir pins of TB6600 and DM556 (all from Aliexpress ).
Any idea what is going wrong?
Thanks in advance.
I have Pi3+, Debian Bullseye 64bit and IO+ board which works for some time but aborts with "OSError: [Errno 121] Remote I/O error", no matter what I have tried to tune config.txt.
There is RTC clock connected (from Aliexpress but they seem to be all similar), pigpio daemon running for encoder (currently disconnected), and pyfirmata to control step motors via USB and Arduino Due/AccelStepper.
Current parameters:
dtparam=i2c_arm=on,i2c_arm_baudrate=100000
dtoverlay=i2c-rtc,ds3231
enable_uart=1
dtoverlay=pi3-disable-bt
core_freq=250
dtoverlay=vc4-fkms-v3d
gpu_mem=128 # Switched from CMA to discrete value
# for PIGPIO
iomem=relaxed
strict-devmem=0This error occurs quite shortly, even without sending any data via Firmata to Arduino, and PIGPIO just running idle. IO+ is connected to 8-relay board and ena/dir pins of TB6600 and DM556 (all from Aliexpress ).
File "/home/pi/LinW/BA_cnc_iopiplus.py", line 64, in cnc_iopiplus_set_pin
bus_obj.write_pin(pin, state)
File "/usr/local/lib/python3.9/dist-packages/IOPi/IOPi.py", line 509, in write_pin
self.__set_pin(pin, value, self.GPIOA, self.GPIOB)
File "/usr/local/lib/python3.9/dist-packages/IOPi/IOPi.py", line 246, in __set_pin
curval = self.__bus.read_byte_data(self.__ioaddress, reg)
OSError: [Errno 121] Remote I/O errorAny idea what is going wrong?
Thanks in advance.
15/12/2021
Posted by:
andrew
Hi
The problem you are having is most likely caused by a conflict between the IO Pi and the RTC.
Linux will periodically communicate with the RTC. When this happens the I2C bus is blocked from all other communication so if you try to access the IO Pi at the same time you will get a Remote I/O error.
The easiest way to get around this problem is to use a try/except around the write_pin function call in python code and if an error occurs wait for a few milliseconds and try repeating the write_pin call.
The other option would be to disable the i2c-rtc and ds3231 overlays and write a python program to manually get the date and time from the ds3231 and update the system time when the Raspberry Pi boots.
The problem you are having is most likely caused by a conflict between the IO Pi and the RTC.
Linux will periodically communicate with the RTC. When this happens the I2C bus is blocked from all other communication so if you try to access the IO Pi at the same time you will get a Remote I/O error.
The easiest way to get around this problem is to use a try/except around the write_pin function call in python code and if an error occurs wait for a few milliseconds and try repeating the write_pin call.
The other option would be to disable the i2c-rtc and ds3231 overlays and write a python program to manually get the date and time from the ds3231 and update the system time when the Raspberry Pi boots.
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