Good day,

We are using the display in a USB powered design. It gets about 4.8V, so well within spec. I noticed different reset behavior across 5 modules. 1 of them always resets, 3 of them reset from time to time and 1 never resets at all. My first idea was that the USB power might be poor quality. When I put them on a lab power supply (5V) the reset becomes a little better but there is still the one that does not reset at all. So I turned my attention to the reset circuit. Since the PIC does POR anyway, I decided to get rid of the capacitor (C1) on the MCLR of the PIC. Result: all modules are resetting just fine. So I think there is a timing issue between the reset of the PIC and the ASIC of the display. Can you confirm this or investigate?

Finally I replaced the capacitor on the MCLR with a 100nF and this seems to work on all the displays I have.

The PCB is marked V2, the firmware version is 3.3. The original capacitor is 4.7µF,  the pull-up resistor is 10k. Hope this helps.

Kind greetings.

 Yes, you are right, you can even remove the C1. Thanks for your investigation.