STM32 Nucleo. Problems with RESET

[d_aliaga]

Posted on February 17, 2016 at 01:15

Hello and thanks always

I am programming a STM32 Nucleo with mbed and I have a curious situation. If it sounds familiar to you, I would appreciate any pointer, advice or commentI have successfully programmed the nucleo to display something on a TFT LCD. However if I plug the nucleo to my PC (powering it) the LCD keeps blank meaning the LCD was not initialized.However, if I press the RESET button

of the Nucleo

 the program runs successfully and as long as I keep the nucleo plugged to the PC I can program it any number of times it always work.It is only when I unplugged and plug it that the program fails...why would this be happening??(As a side note, how can I reset my nucleo from software -without touching the reset button)  #reset

[Tesla DeLorean]

Posted on February 17, 2016 at 04:56

Not sure I've seen it do that, but I would suspect the ST-LINK/mbed code is getting control of the core and then halting it.

CMSIS has the NVIC_SystemReset() command

[d_aliaga]

Posted on February 25, 2016 at 02:58

Thank you very much for your reply.

Any idea how to solve this issue?( I naively thought resetting by software would work but then I realize that would cause to reset it continuously for ever since once the STM is resetted it will reset it again. I put the command and the screen went blank- is it poissible that the first time is happening the same???)Any other idea any person out there???

[Kraal]

Posted on February 25, 2016 at 09:07

Hi !

To me it looks more like a difference of power up/startup times between the STM32 and the LCD. When you plug the nucleo, the LCD has not the time to be ready before the STM32 sends the initialization sequence. But for subsequent reset of the STM32, the LCD is already powered ON and ready. One thing you could try is to add a sufficient delay before sending the initialization sequence to the LCD.Have a nice day,Carl