[tdelprat]

I realized that I was looking at the schematics on page https://nootropicdesign.com/matrixbackpack/design.html whereas I have a V2 board.

So, I installed Eagle to be able to view the V2 schematics.

It seems that the “magical” pin that makes the board work when I touch it is not connected to 5V but to what I think is the PIN 16 (PB2 ?) of the ATMega328.

Not sure if this help or even makes any sense …

[tdelprat]

Hi,

Thank you for your answer.

Switching the power supply for a “switching power adapter” did not solve the issue.

I did not succeed in solving the issue by bending the pins or unplugging / plugging the backpack card.
It does not seem to be a pressure issue.

To be clear, even barely touching the 5V pin (on the backpack board) indicated in my previous post makes the panel work (or at least do something).
It does not work if I touch with plastic but works if I use my finger or even paper(!).

As I said, last time I did electronic was about 20 years ago and even back then I was a beginner: it seems to me like something related to power supply or ground, but I obviously may be wrong.

Any other advice for me?

Thanks.

Tiry

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