STM32F407-Discovery Reset Delay When Power Applied.

[AAhme.41]

Dear All,

I have a STM32F407-Discovery Kit, I have a problem that when I Power up my Discovery Kit it takes 2 to 3 Seconds to initialize, and during this time there is Garbage values on GPIO Pins. Please tell me what is the problem?

[Karl Yamashita]

If you don't post any code, then we don't know what you're trying to initialize.

[Tesla DeLorean]

Probably the ST-LINK holding it reset.

Check if there is a solder bridge for NRST you can unmake.

Still likely to be a brief delay from your code starting to the point you initialize the clocks/pins. Understand the flow of the code and what it is doing, and where along the time line.​

[AAhme.41]

Thanks for your answer, When I connect & power it through USB Cable then it does take any delay, it takes delay only when I Power it from VDD Pins. I Comment all the code just setting the GPIO pins in startup.

[Karl Yamashita]

Sounds like you're not powering up the Discovery board correctly. Have you checked to see when you power VDD that the voltage isn't rising slowly to 3V? Is X2 oscillating right away when you supply power to VDD? Or maybe an issue with NRST pin staying low briefly before going high?