I’ve built a simple dual time zone clock with a Sparkfun Thing Plus and two alphanumeric displays connected in series with Qwiic cables. The clock will run for hours without issue but occasionally I will look at it and see one of the two displays has gone dark. A reset fixes it immediately.
This happens whether the devices are connected to a USB power brick or into the USB port of a PC.
Not sure where to start to look for the problem.
If you haven’t already, be sure to disable one set of i2c pull-up resistors:
The Qwiic Alphanumeric Display Breakout has onboard I2C pull up resistors; if multiple sensors are connected to the bus with the pull-up resistors enabled, the parallel equivalent resistance will create too strong of a pull-up for the bus to operate correctly. As a general rule of thumb, disable all but one pair of pull-up resistors if multiple devices are connected to the bus. If you need to disconnect the pull up resistors they can be removed by cutting the traces on the corresponding jumpers highlighted below.
