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STM32L031 reading 5 digital Inputs work fine, but doing the same with 10 inputs fail.

Question asked by Hugo Balette on Nov 16, 2017
Latest reply on Nov 16, 2017 by Hugo Balette

Hi !


I'm working on a STM32L031 project, and I need to read 10 digital 0V-3v3 Inputs.

Everything works fine if i'm reading 5 inputs (PA3, PA4, PA5, PA6, PA7). It is also working if I'm reading 5 other inputs (PB3, PB4, PB5, PB6, PB7).

But as soon as I plug both PA3, PA4, PA5, PA6, PA7 and PB3, PB4, PB5, PB6, PB7, it stops working.


I checked using a voltmetre in the 10 inputs config, and 4 inputs don't rise to 3v3, but only 1V.

So It only reads 3 inputs of (PA3, PA4, PA5, PA6, PA7) and 3 inputs of (PB3, PB4, PB5, PB6, PB7).


Would it be a problem of current sinking ? or just a wrong software configuration ?

I tried configuring inputs with and without pull down.

I checked GND is common to every inputs.


Any ideas ?


thanks for your time.