Problem with loops on STM32F103C8T6

[sobasanhe]

Hello! I’m using Keil uVision to program the stm32f103c8t6 (blue pill). I’m having problems with the loops when trying to turn on and off the LED on pin 13 port C. I just wanted to use a loop to generate a delay without needing to use timers, since I wanted to generate a simple program. But when I download it to the board, the LED stays on instead of turning on and off, regardless of the wait value I put in. I would appreciate it if you could tell me if I’m doing something wrong and indicate the solution. Thanks in advance. The code is as follows:

 

#include "stm32f10x.h"

 

#define RCC_CR (*((volatile uint32_t *)0x40021000)) 

#define RCC_APB2ENR     (*((volatile uint32_t *)0x40021018)) 

#define RCC_CFGR      (*((volatile uint32_t *)0x40021004)) 

 

#define GPIOC_CRH (*((volatile uint32_t *)0x40011004)) 

#define GPIOC_ODR (*((volatile uint32_t *)0x4001100C))

 

int main(){

RCC_CR |= 0x1;  

while( !(RCC_CR & 0x2) ){}

 

RCC_APB2ENR |= 0X10;

while( !(RCC_APB2ENR & 0x10) ){} 

 

RCC_CFGR = RCC_CFGR & ~(0x3u); 

 

GPIOC_CRH |= 0x600000;

int i=0;

while(1){

GPIOC_ODR = 0x0; 

 while(i<1000000){ i++}

GPIOC_ODR = 0x2000; 

while(i<1000000){ i++}

}

}

 

 

[TDK]

You're missing some semicolons in your code. It won't even compile.

Change "int i" to "volatile int i" so the compiler doesn't optimize it out.

Probably also want to set i back to 0 before each loop. After the first loop, all of the other loops will immediately exit.

Can always step through the code and verify registers are changed appropriately. I guess not on the blue pill. There are better boards for development.

[sobasanhe]

Oh! Thank you for the response, it was helpful. In the post, I omitted the semicolons and the resets of the variable, but in the original code, I had them. In general, it was solved by making the variable volatile. Seriously, thank you very much for the quick response.