STM32L476 with external flash not work after re-power up

[shaoziyang]

I have diy a STM32L476RG board, with a 32KHz crystal and 1Mbytes external flash.

If I not using external 1Mbyte flash, it works fine. If I enable external flash, after upgrade firmware with ST dfuse util and click "leave DFU mode" button, it works and can read/write 1Mbytes pyb flash. But when I disconnect USB cable and reconnect again, it will not work, it will show pyb flash disk, but disk can't be read/write. And it maybe works after long time wait (several minutes) sometimes. And if I only enter DFU mode and click "leave DFU mode" button (not upgrade firmware), it will works.

What might have caused it?

I use micropython 1.11, and modify board define from STM32L476DISC.

[jimmo]

Perhaps there's something wrong with the config and accessing the flash is causing something to be overwritten. (i.e. straight after DFU everything is fine, then subsequently there's been some corruption).

Can you share your board definition (link to github maybe?).

[shaoziyang]

My define:

PYBL476.ZIP

(5.51 KiB) Downloaded 222 times

[shaoziyang]

I found the problem is cause by ldo, I increase capacitance, and it work now.