Using UART bootloader on STM32G030J6

[DBong.1]

I am attempting to activate the bootloader mode on the STM32G050J6 (SO8N package). It is unclear to me from the documentation which pins are to be used. Currently, I am using pins 1 and 8 (USART1_RX and USART1_TX in the documentation respectively) as USART pins. Additionally, I am using pin 8 as BOOT0 pin. So what I do is as follows:

• Short RST to 0V net
• Short BOOT0 to 3.3V net
• Connect RX and TX pins to USB to UART adapter
• Apply power to the board and the adapter at the same time
• Remove short from RST
• Remove short from BOOT0 (which is also USART1_TX)

Then when I attempt at activating the bootloader through the STM32CubeProgrammer app, I get an error saying that the program did not receive an acknowledge and the bootloader could not be activated.

Alternatively, I have access to a ST-LINK v2 device. My objective really is to program the micro and be able to use UART, but the UART pins conflict with the SWD pins.

[Tomas SIRUCEK]

Hi,

well, to the TSSOP20 it definitely applies. I have to admit, I am not sure, how it works with the bigger packages. With the native PA9/PA10 it should work and maybe also with those remapped (but this is not validated answer, just my guess). Anyway I would recommend to use native ones or preferably USART2 on PA2/PA3, which are available on bigger packages.

Have a nice day.

[ne562]

Clear nBOOT_SEL bit in OPTION to enable BOOT pin, here is code for first upload:

#include "stm32g030xx.h"
 
// clear OPTION.nBOOT_SEL bit
int main(){
	// check if nBOOT_SEL bit is set
	if(FLASH->OPTR & FLASH_OPTR_nBOOT_SEL){
		// unlock flash/option
		FLASH->KEYR    = 0x45670123;
		FLASH->KEYR    = 0xCDEF89AB;
		FLASH->OPTKEYR = 0x08192A3B;
		FLASH->OPTKEYR = 0x4C5D6E7F;
 
		while(FLASH->SR & FLASH_SR_BSY1);
 
		// clear nBOOT_SEL bit
		FLASH->OPTR &= ~FLASH_OPTR_nBOOT_SEL;
 
		// write
		FLASH->CR   |= FLASH_CR_OPTSTRT;
		while(FLASH->SR & FLASH_SR_BSY1);
	}
 
	while(1);
 
	return 0;
}