The JTAG port of the stm32f103 series chip is used as a normal IO

The chip used is stm32f103c8t6.

Today, when debugging the board, I found that the LED light on the PA15 port only has an intermediate level of 2.3V regardless of whether the output is high or low. Later, Baidu said that this port (PA15--JTDI) is used as a JTAG debugging port by default and needs to be configured as a normal IO port. So I wrote two sentences according to that person's method: RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO,ENABLE);GPIO_PinRemapConfig(GPIO_Remap_SWJ_Disable,ENABLE);

It would have been fine if I hadn't written it, but after writing it, even the SWD port that was originally used to download and debug programs could not be used... Later, I found the correct way to write it in the STM32 library: RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO,ENABLE); GPIO_PinRemapConfig(GPIO_Remap_SWJ_JTAGDisable,ENABLE); This means not to use JTAG but to keep SWD. Neither the previous JTAG nor SWD will be kept.

The problem has been discovered, but what can I do? Now even SWD cannot be used... I used the serial port to download, but I was dumbfounded when I saw the board (I drew it myself), BOOT1 was floating, and BOOT0 was grounded... There was no way to connect the jumpers, so I grounded BOOT1, and pulled BOOT0 up to 3V3 through 4K7, and then used the MCUISP serial port to download (those who have used the Wildfire development board should know). The software first erased the chip and then wrote a new HEX file (the new HEX file is the second code above, only SWD is retained).

The download is successful, then pull up BOOT0 (it doesn’t matter if BOOT1 is still grounded, it is very clear in the data sheet), and after connecting to ST-LINK, SWD mode can download normally, and the PA15 port can also control the light normally.

From this we can see: 1. If the pin resources are not very tight, it is still better to pull the BOOT1 pin low; 2. In the first code above, the 5 IOs originally occupied by JTAG can be used as ordinary IO ports, but the program can only be downloaded through the serial port in the future.

1. void LED_GPIO_INIT(void)  

2. {  

3.     GPIO_InitTypeDef GPIO_InitStructure;  

4.       

5.     RCC_APB2PeriphClockCmd( RCC_APB2Periph_GPIOA, ENABLE ); //PA clock enable  

6.       

7.     GPIO_InitStructure.GPIO_Pin = LED_PIN;  

8.     GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP; //PULL PUSH   

9.     GPIO_InitStructure.GPIO_Speed ​​= GPIO_Speed_50MHz;  

10.       

11.     GPIO_Init( LED_PORT, &GPIO_InitStructure );  

12.       

13.     // for PA15 JTDI REMAP  

14.     RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO,ENABLE);  

15. // GPIO_PinRemapConfig(GPIO_Remap_SWJ_Disable,ENABLE); // JTAG&SWD DISABLE  

16.     GPIO_PinRemapConfig(GPIO_Remap_SWJ_JTAGDisable,ENABLE); // JTAG DISABLE,SWD ENABLE  

17.       

18.     GPIO_ResetBits( LED_PORT, LED_PIN ); //TURN OFF LED  

19. }