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Dfinitski / N7DDC-ATU-100-mini-and-extended-boards

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display not working after freeze #115

Closed nathanielc closed 2 months ago

nathanielc commented 2 months ago

I recently built the kit and it was working well. However the display stopped updating when I was using it, so I turned the device off and on. When powered back up the display no longer works. The tuning function does still work, I can hear the relays clicking and can measure a low swr though the tuner.

I bought a replacement display thinking it was a defective unit but the new display doesn't work either. Any ideas what to check next? Would reflashing the pic be of any use?

I can confirm the display gets 5v vdd when powered on. But otherwise don't have tools to check the clock or data pins.

Thanks

Dfinitski commented 2 months ago

Hi. If you have a simple multimeter, check the SCL and SDA lines, what is voltage there . When the device is powered off, check a short to ground, Vdd or each other.

nathanielc commented 2 months ago

When the device is powered on voltage on each pin is:

VCC: 5.00V SCL: 3.75V SDA: 0.22V

When the device is powered off checking short to ground the SDA pin has only ~175 ohms to ground. All other pins are not shorted to ground or any other pin. Is this expected? Thanks for the debugging direction.

Dfinitski commented 2 months ago

Seems like SDA port on the PIC has burned.

nathanielc commented 2 months ago

Ok I'll try to replace it, thanks for the help. Found the part here https://www.mouser.com/ProductDetail/Microchip-Technology/PIC16F1938-I-SS?qs=DAV8Y8VhPTJLSX3OKAfRPQ%3D%3D&mgh=1