Program does not execute after resetting power

[Ameya M]

Hello,

We have developed a custom board having STM32F746NGHx MCU based of the design of the STM32F746G-DISCO board.

We are using ST-Link Utility and ST LinkV3-SET Debugger in JTAG mode to flash.

The board gets flashed and the program is executed after flashing is complete and the display (TFT _ LCD) shows desired output.

But, if the board is reset, the program does not execute and the display shows garbage.

But it executes again only if the STLinkV3-SET Debugger is disconnected and reconnected to the PC.

Please advice on the issue.

Thanks,

Ameya

[Tesla DeLorean]

Make sure BOOT0 is pulled LOW so your code runs.

Instrument your code to use a USART so you can understand what's happening internally in the absence of a debugger connection.

Have ErrorHandler() and HardFault_Handler() output actionable data so you can determine what happened if they end up in those routines.

Check timing loops and clocking. Check that external clocks start properly.

[BTrem.1]

I had a recent similar condition. Debugger worked but would not boot without debugger. Check the hardware timing of your NRST reset. If the reset time is inadequate you will have a dead brick on power reset but with debugger it gives an adequate reset pulse.