Program stm32g474re from Bootloader via I2C

[AZHUK.1]

Good afternoon.

I am trying to program STM32G47X through the built-in bootloader using a protocol I2C from another microcontroller.

Document 2606 on page 212 indicates the slave address 0b1010100x. I managed to get through only at 0b1010011x. Is this a bug in the documentation?

Document 4221 also has very little information. I enter bootloader mode by setting boot1 to 1 and releasing the reset.

//i2c 100kHz
 
HAL_StatusTypeDef status;
 
uint8_t tmp[2];
uint8_t dat[21];
uint8_t ACK;
 
	while(HAL_I2C_GetState(hi2c) != HAL_I2C_STATE_READY);
	status = HAL_I2C_Master_Transmit_IT(I2cHandle, 0xa6, dat, 1);
	while (HAL_I2C_GetState(hi2c) != HAL_I2C_STATE_READY) ;
	status = HAL_I2C_Master_Receive_IT(I2cHandle, 0xa7, &ACK, 1);
while(1)
	{
		tmp[0] = 1;
		tmp[1] = 0xfe;//XOR tmp[0]
		while (HAL_I2C_GetState(hi2c) != HAL_I2C_STATE_READY) ;
		status = HAL_I2C_Master_Transmit_IT(I2cHandle, 0xa6, tmp, 2);
		memset(dat, 0, sizeof(dat));
		while (HAL_I2C_GetState(hi2c) != HAL_I2C_STATE_READY) ;
		status = HAL_I2C_Master_Receive_IT(I2cHandle, 0xa7, &ACK, 1);
		if (ACK == 0x79)
		{			
			while (HAL_I2C_GetState(hi2c) != HAL_I2C_STATE_READY) ;
			status = HAL_I2C_Master_Receive_IT(I2cHandle, 0xa7, dat, 2);	
//I accept only zeros!
		}
		else if (ACK == 0x1f)//nack
		{
//Sometimes I get here
		}
		else if(ACK == 0x76)//busy
		{
		}
			else
		{
		}

Often, the slave controller presses the SCL line to the ground. And you have to wait up to 10 seconds.

Maybe someone has an example working?

I don’t understand how to receive data after the response ACK == 0x79

[TDK]

If you want to use I2C in blocking mode, use HAL_I2C_Master_Transmit instead of HAL_I2C_Master_Transmit_IT. The latter transfers asynchronously and you need to wait for completion before accessing the data. Which you do in most places, but not all.

> I don’t understand how to receive data after the response ACK == 0x79

Not sure what you mean. You receive data with HAL_I2C_Master_Receive.

From the app note:

Note: The host frame can be one of the following:

• Send Command frame: The host initiates communication as master transmitter, and sends two bytes to the device: command code + XOR.

• Wait for ACK/NACK frame: The host initiates an I2C communication as master receiver, and receives one byte from the device: ACK or NACK or BUSY.

• Receive Data frame: The host initiates an I2C communication as master receiver, and receives the response from the device. The number of received bytes depends on the command.

• Send Data frame: The host initiates an I2C communication as master transmitter, and sends the needed bytes to the device. The number of transmitted bytes depends on the command.

[AZHUK.1]

It seems to figure it out. The loader sends data by one byte

if (ACK == 0x79)
		{			
			status = HAL_I2C_Master_Receive_IT(I2cHandle, 0xa6, &dat[0], 1);
//https://www.st.com/resource/en/application_note/dm00072315-i2c-protocol-used-in-the-stm32-bootloader-stmicroelectronics.pdf
//page 11
//Byte 2: Bootloader version (0 < Version ≤ 255) (for example, 0x10 = Version 1.0)
 while (HAL_I2C_GetState(I2cHandle) != HAL_I2C_STATE_READY) ;
 status = HAL_I2C_Master_Receive_IT(I2cHandle, 0xa6, &dat[1], 1);	
//Byte 3: ACK
 while (HAL_I2C_GetState(I2cHandle) != HAL_I2C_STATE_READY) ;
		}