AnsweredAssumed Answered

STM8AF Output NRST Pin signal

Question asked by david.ye on Apr 11, 2018
Latest reply on May 3, 2018 by Maxime TEISSIER

Dear all,

 

First I would like to thank you for any help that you might give me.

My purpose is to flash an empty code in the uC (STM8AF5288TAY) but its always says "lost SWIM communication".

 

After analyse of our self designed board, I remarked that the problem might come from the NRST pin of the uC.

There is only a condensator connected to this pin during my test :

 

But you can see that the signal NRST(shown below) is not pulled up as it should be :

 

If I remove the condensator, I have this on the NRST pin :

 

Please can someone tell me why I have this signal in the NRST pin while there is nothing going on? In my undersanding I should have 5V straight while nothing is happening; So where this signal comes from?

 

I am really looking forward for an answer or advice as I can not find the solution since weeks and cannot flash any program.

 

Thank you in advance,

Ye David 

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