How to port code to a different MCU of the same family? like from STM32F401RE to STM32F401RC?

Mbed OS
#1

Hi,

I am trying to port an app built around STM32F401RE/NUCLEO_F401RE to its sibling STM32F401RC, to save a bit money on each MCU. I thought this is going to be straightforward but so far it doesn’t go well.

On the same board, a blinky built with STM32CubeIDE seems to work just fine.

int main(void)
{
  HAL_Init();
  SystemClock_Config();
  MX_GPIO_Init();
  MX_USART6_UART_Init();
  while (1)
  {
	HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_5);
	HAL_Delay(1000);
  }
}

But blinky built with Mbed somehow doesn’t work.

int main() {
    //Watchdog &watchdog = Watchdog::get_instance();
    //watchdog.start(30000);
    //printf("system started\r\n");

    DigitalOut led(PA_5);

    while (1)
    {
        //printf("System running\r\n");
        led = !led;
        ThisThread::sleep_for(1000);
        //watchdog.kick();
    }
}

Since the only difference between STM32F401RE and F401RC is the size of flash, I assume as long as code can fit into F401RC, it should run fine.

What am I missing here?

Thanks in advance.

#2

The problem is STM32F401RC has only 64KB RAM while F401RE has 96KB. Once this is changed is linker script accordingly, the blinky seems to work just fine.

https://os.mbed.com/docs/mbed-os/v5.15/reference/memory.html

1 Like
#3

Hi @zhiyong ,

I am facing exactly the same issue but cannot make it work.

What is it that you changed?

Did you create a custom target?

Thanks,
Lluis

#4

Top of my head, I think what I did was changing the starting address of RAM in linker file. The project I was working got shelved later on so I don’t have any recent memory about it.

#5

Hello Lluis,

Create a custom target custom_targets.json with the following content:

{
    "STM32F401RC": {
        "inherits": [
            "MCU_STM32F4"
        ],
        "macros_add": [
            "STM32F401xC"
        ],
        "extra_labels_add": [
            "STM32F401xC"
        ],
        "supported_form_factors": [
            "ARDUINO",
            "MORPHO"
        ],
        "detect_code": [
            "0720"
        ],
        "device_name": "STM32F401RC"
    }
}

With this, Mbed will use the startup and linker files for the STM32F401xC models and set the appropriate SRAM size, interrupt vector table, MBED_ROM_START and MBED_ROM_SIZE.

1 Like