STM32G0 can't program through native UART bootloader - Failure 20% on same board

[Himanshu_Dhiman]

Hello,

I am using STM32G0B1cbt6. And I am using native bootloader to update firmware. But in some boards not able to update firmware, it is giving below error:

And when we replaced the MCU then bootloader started working normally.

 The failure percentage is like out of 100, in 5 to 10 MCUs we are facing problem. 

What could be the reason? And how it can be resolved?

This is a custom board.

I am attaching the schematic below. Which running on standard 3.3V supply.

Is there any way to check if the bootloader is corrupted and if corrupted is there any way to reprogram it? 

I have tried the below methods and no resolution found.

1. Remount same MCU: Some started working, some not working
2. Replaced new MCU: Some started working, some not working
3. Boot 0 pin HIGH at startup: Some started working, some not working
4. Boot 0 pin LOW at startup: Some started working, some not working
5. NRST pull up resistor removed: Some started working, some not working
6. Connected ST Link programmer and tried OTA: Not working
7. Observed Boot 0 and NRST with scope: No change while updating.

[TDK]

> The failure percentage is like out of 100, in 5 to 10 MCUs we are facing problem. 

Probably a hardware issue then. Maybe bad solder joints or other manufacturing defect.

The schematic you attached is too small and blurry to be completely legible.

Can you connect over SWD?

[Himanshu_Dhiman]

Yes, the boards can be programmed by SWD. And while debugging the code jumps into bootloader and become inaccessible.