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Unable to enter USART bootloader - STM32G474RCT6

Associate II

I am trying to enter USART1 bootloader (Pin PC4 and PC5) for STM32G474RCT6 MCU

We are following AN2606 and tried to keep the option bit configurations as per the highlighted row under pattern 14


Bit status:


The Boot0 pin (PB8) is NOT  pulled down with registered and is tied to VDD line via a push button

To enter the bootloader, we press the the button connected to PB8 and the reset pin in a sequence like below:

1. Hold the boot button 

2. Hold reset button

3. Release reset button

4. Release boot button


We are using the Flash Loader Demo exe for flashing 


Getting below error while after applying above mentioned sequence of boot and reset pins


Please confirm if the above steps are correct and what must be done to enter the boot loader

Also, is there another way to confirm if device is in boot mode config





ST Employee

Dear @shraddhs10 ,


That utility is no more recommended for new design as below, please use STM32CubeProgrmmer instead  and let us know if the behavior is the same ? 


Hope it helps ,


Connected how and with what?

CMOS level signals are not RS232 compatible

Noise on other inputs might be taken as first-contact, say a GPS/GNSS chirping continuously from startup.

Reset and try again

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