SparkFun 20x4 SerLCD - RGB Backlight (Qwiic) fails with a Raspberry Pi OSError: [Errno 121] Remote

Components & Accessories Displays
1

Using:

Raspberry Pi 3B+, Raspberry PI OS (32 bit) with I2C activated

Python 3.9.2

SparkFun 20x4 SerLCD - RGB Backlight (Qwiic) LCD-16398

SparkFun Qwiic pHAT v2.0 for Raspberry Pi DEV-15945

Phat connected to the LCD via Qwiic cable

sparkfun-qwiic-serlcd library installed

sparkfun-qwiic-i2c drivers installed

The sparkfun example python program:

from future import print_function

import qwiic_serlcd

import time

import sys

def runExample():

print(“\nSparkFun Qwiic SerLCD Example 1\n”)

myLCD = qwiic_serlcd.QwiicSerlcd()

if myLCD.connected == False:

print(“The Qwiic SerLCD device isn’t connected to the system. Please check your connection”, \

file=sys.stderr)

return

myLCD.setBacklight(255, 255, 255) # Set backlight to bright white

myLCD.setContrast(5) # set contrast. Lower to 0 for higher contrast.

myLCD.clearScreen() # clear the screen - this moves the cursor to the home position as well

time.sleep(1) # give a sec for system messages to complete

myLCD.print(“Hello World!”)

counter = 0

while True:

print(“counter: %d” % counter)

myLCD.setCursor(0,1)

myLCD.print(str(counter))

counter = counter + 1

time.sleep(1)

if name == ‘main’:

try:

runExample()

except (KeyboardInterrupt, SystemExit) as exErr:

print(“\nEnding Example 1”)

sys.exit(0)

This program will run anywhere from a few seconds to 10 minutes and then fail with a Raspberry Pi OSError: [Errno 121] Remote error.

the i2cdetect -y 1 command shows the lcd is connected at the 0x72 address before and after the failure. after the failure, an additional address of 0X08 appears for a short time.

2

I’d first try re-performing the raspi-config (& ensure auto-load to kernel is enable too) https://learn.sparkfun.com/tutorials/qw … ing-the-pi and then maybe trying a different port?

One thing that can happen is if you have multiple sensor attached, the combined pull-up resistance can become too high for the bus to function…if the above stuff doesn’t work, try cutting the i2c jumper on the pHat (go to the “Jumpers” section https://learn.sparkfun.com/tutorials/qw … 8#hardware which has an associated photo) and see how that goes