Hello,
I have 2 STM32 Nucleo F746ZG boards, and I am trying to use one board (MCU 1) to program the second board (MCU 2) through its default bootloader through code. To do so, I used the following command in the MCU2 to start its default bootloader:
#define DEFAULT_BOOTLOADER_ADDRESS 0x1FF00000
BOOT_JumpToAddress(DEFAULT_BOOTLOADER_ADDRESS);
void BOOT_JumpToAddress(uint32_t address)
{
printf("Jumping to 0x%08X\r\n", address);
// Function pointer to reset handler
void (*app_reset_handler)(void) = (void *)(*((volatile uint32_t *)(address + 4U)));
// Disable RCC, HAL, reset SYSTICK, and remap vector table offset
HAL_RCC_DeInit();
HAL_DeInit();
SysTick->CTRL = 0;
SysTick->LOAD = 0;
SysTick->VAL = 0;
SCB->VTOR = address;
uint32_t msp_value = *((volatile uint32_t *)address);
__set_MSP(msp_value);
// Jump into application
app_reset_handler();
}
Then, on the programmer, I send the start byte 0x7F. When I receive ACK, I send the bytes for the "Go to application" command, which are 0x21 and 0xDE. After receiving ACK, I send the bytes for the address and the checksum using the command below:
uint32_t applicationAddress = 0x08040000;
addrBuf[0] = (applicationAddress >> 24) & 0xFF;
addrBuf[1] = (applicationAddress >> 16) & 0xFF;
addrBuf[2] = (applicationAddress >> 8) & 0xFF;
addrBuf[3] = (applicationAddress >> 0) & 0xFF;
addrBuf[4] = addrBuf[0] ^ addrBuf[1] ^ addrBuf[2] ^ addrBuf[3];
I send that buffer, and I get back ACK. When I monitor the PuTTY output on my MCU2, I can see that "Starting appl" has been printed out, which indicates that the bootloader jumped to the application slot, as that printf statement is printed after all the configurations is done. However, the entire string is not printed, and instead after that printf statement, the MCU 2 starts running the custom bootloader, another project that I am trying to do.
So, why does that happen? I think that something causes the MCU2 to reset while it is running the application code, causing it to default to running the custom bootloader (this behaviour is expected: I have set it such that whenever the MCU 2 resets, it runs my custom bootloader first). Does the BOOT0 pin need to be held high while I am running the default bootloader code? Right now, I have not been messing with it. Or do I need to set SCB->VTOR = 0x08040000 somewhere?
The problem is not with the application code, because it runs fine if I run it on its own.
I would greatly appreciate any help. Thank you!
