Unable to View Output from STM32 Board via Serial Port

[Ratul99]

Greeting Everyone,

I am facing an issue with my STM32 board having STM32F103C8T6 as MCU, while trying to see a normal "Hello World" output. After debugging the board, I attempted to connect it to my PC via the serial port. To ensure proper communication, I installed the necessary Virtual COM Port drivers from the STM32 website.

However, my PC is not detecting the COM port to which the STM32 board is connected. Additionally, when I try to view the output on the Debugger Console within STM32CubeIDE, I encounter an error that prevents me from seeing the expected output.

I have written the code below that I'm using to print the Hello World which I have found online. Also I do not know if their is any problem on the code. With this I have also attached the Pin Configuration and Clock configuration details below as images.

#include "main.h"
#include "usart.h"
#include "gpio.h"
#include <stdio.h>
#include <stdint.h>
#include <stm32f1xx_hal_conf.h>


void SystemClock_Config(void);
int _write(int file, char *ptr, int len)
{
int i=0;
for(i=0;i<len;i++)
ITM_SendChar((*ptr++));
return len;
}

uint8_t count = 0;
int main(void)
{
HAL_Init();
SystemClock_Config();
MX_GPIO_Init();
MX_USART2_UART_Init();
while (1)
{
   HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_5);
   count ++;
   printf("Hello World count = %d \n",count);
   HAL_Delay(250);
}
}



void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
RCC_OscInitStruct.HSIState = RCC_HSI_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL2;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}

RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                                       |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK)
{
Error_Handler();
}

}



void Error_Handler(void)

{



__disable_irq();

while (1)

{

}



}



#ifdef USE_FULL_ASSERT



void assert_failed(uint8_t *file, uint32_t line)

{



}

#endif

Could you please assist me in resolving this issue? I would appreciate any guidance or troubleshooting steps you can provide to help me get the serial communication working and view the output correctly.

Thank you for your support!

Best regards,
Ratul Kar

ratul.pcbwork@gmail.com

[mƎALLEm]

Hello @Ratul99 and welcome to the ST Community,

What board are you using? ST board? Custom board? blue/black pill board? and how did you connect the board to a PC with a detailed hardware description.

Thank you

PS: please use </> button to paste your code: see this post. I'm editing your post.

[mƎALLEm]

+

You did the printf retarget to the ITM not to the serial port. 

ITM_SendChar((*ptr++));

Look at this example for STM32CubeF1 package:

https://github.com/STMicroelectronics/STM32CubeF1/tree/master/Projects/STM32F103RB-Nucleo/Examples/UART/UART_Printf

Look also at this thread: https://community.st.com/t5/stm32cubemx-mcus/how-to-retarget-printf-on-uart/td-p/380053

[Ratul99]

Hello @mƎALLEm 

Thank you for the response. As you have asked we are using a custom board and for the debugging part we have used ST Link V2. If anything more details needed please feel free to ask.

Regards

Ratul Kar

[Ratul99]

Hi @mƎALLEm 

I will look into this and let you know if I can get any results out of it.

Thanks again

Ratul

[Andrew Neil]

---

@Ratul99 wrote:

we are using a custom board

---

Then please post the schematic.

---

@Ratul99 wrote:

for the debugging part we have used ST Link V2.

---

Is it genuine ?

https://community.st.com/t5/stm32-mcus/how-to-recognize-a-genuine-st-link-v2-versus-a-cloned-one/ta-p/49471

In particular: https://community.st.com/t5/stm32-mcus/how-to-recognize-a-genuine-st-link-v2-versus-a-cloned-one/tac-p/703663/highlight/true#M965

---

@Ratul99 wrote:

I encounter an error that prevents me from seeing the expected output

---

What error, exactly?

---

@Ratul99 wrote:

If anything more details needed please feel free to ask.

---

Please see: How to write your question to maximize your chances to find a solution.

You haven't said what host system you're using, nor what IDE version.

PS:

This is a public forum, visible to anyone & everyone on the internet - so you might want to re-think publishing your email address ...

[Andrew Neil]

Before adding the complexities of printf redirection, be sure that you can get basic direct UART IO working first.

https://community.st.com/t5/stm32-mcus/how-to-redirect-the-printf-function-to-a-uart-for-debug-messages/tac-p/733969/highlight/true#M1096

[Tesla DeLorean]

The ITM would come out of PB3 SWO via the SWV Viewer in STM32 Cube Programmer or your debugger.

The standalone ST-LINK/V2 doesn't provide a USART via a VCP

For your F103 to provide a VCP you'd need to compile as a USB VCP Device and communicate with that and not the USART, but wouldn't really allow for the type of blocking in-line interaction you're attempting. 

Consider a cheap USB to CMOS Serial dongle for USART comms