STM32CubeMX (6.16.1) for STM32C011J6 (SO8) - set PA13/PA14 BACK to STLINK mode

[wb0gaz]

I need to use STM32CubeMX to generate initialization routine for two pins (7,8) on SO8 package of STM32CubeC011 MCU that switches the pin's roles BACK to STLINK mode. I created a new project on STM32CubeMX whose only task is to initialize pins 7 and 8 to PA13/PA14 SWCLK/SWDIO. I wanted to copy the GPIO initialization function MX generated into an existing application which had previously (that is, after start-up) changed the two pins to another mode; after that work is done, the two pins no longer need to be in GPIO mode and can be switched back to STLINK mode to facilitate firmware upgrade/debug/etc.

Two screen captures from STLINK32MX are below (pin assignments and project specifications.)

The resulting (very short) C language program generates the following code for initialization of the two pins:

static void MX_GPIO_Init(void)
{
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */
/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOA_CLK_ENABLE();
/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}

In the code segment above, MX turns on the Port A clock, but does not generate instructions that would modify the alternate function registers for the two pins (7 and 8 on SO8 package) to the values needed to restore the pin's roles to SWDIO and SWCLK. It appears STM32CubeMX assumes the target is already in that mode at power-up/reset, so there is no need to generate the instructions I need.

I've not included any of the code from the original project (which is otherwise working properly) - it  also uses initialization code routines generated by STM32CubeMX then copied into the application under development - that approach has been fully successful to this point. I would like to keep the code solely based on STM32CubeMX generated initialization routines.

Grateful for any advice, follow-up questions, suggestions, or requests for clarification of problem.

[TDK · Accepted solution]

The following code will initialize PA13/PA14 back to their SWD functions:

GPIO_InitTypeDef GPIO_InitStruct = {0};

GPIO_InitStruct.Pin = GPIO_PIN_13;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF0_SWJ;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

GPIO_InitStruct.Pin = GPIO_PIN_14;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF0_SWJ;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

You could have set these pins to a different AF mode to get CubeMX to generate the code for it. Then change the AF to AF0.

[wb0gaz]

Thank you!

That solves the immediate need and provides valuable guidance on using STM32CubeMX going forward!

Dave