MCU working issue.

[GAGGA.1]

I am using STM32F439ZGT6.

I have flashed the code to this controller. After flashing the code when I restart (power off and power on ) the MCU first time, that time unit is working absolute fine but if I power off and power on the unit, that time I am not output. I am not sure whether MCU unit is working or not. I did this iteration two times.

[Piranha]

Except for MCU, there is no information of absolutely anything. How do you expect someone to be able to help?

In 95% of the cases the software is broken...

[GAGGA.1]

What information do you need?

[Tesla DeLorean]

>>What information do you need?

This is a technical venue, we're not doing palm readings..

Is it a custom board, or one others might be familiar with?

If custom, show wiring diagram or schematic.

Check voltages on VCAP pins and on NRST pin, report.

Is BOOT0 pulled low in the design?

What actual debugging have you performed?

What does the code look like?

Does some simple code function? ie output to UART, blink LED, etc.

[GAGGA.1]

Actually I am working from scratch on this controller.

It is a custom board.

I have monitored boot0 pin, it is coming low.

I tried with small code (printing in hyperterminal through UART1) , in debug mode it is working fine. In normal running mode output is not coming.

I have monitored NRST pin, it is coming low.

Whenever I pressed SW1 to reset then one high pulse came at NRST pin.

[waclawek.jan]

NRST is active low, it means, if it is low, the processor is in reset and does not run.

JW