Hi, I am new to microcontroller programming and I am having some trouble making a PWM wave with a STM32F767ZI Nucleo board. I was able to make a led blink with interrupts and now I am trying to fade it in and out, but for some reason I can't. While debuging and can se that at the moment the code executes:
TIM4->CCER |= 0x10; //Enables the result of CC on the corresponding pin
The blue led immediately ligghts up with full power, even though the counter has not been started yet. The full code is shown bellow. Has anyone any idea as to why this is happening, I have read it through The technical reference manual countless times and the General purpose timer cookbook
#include "stm32f767xx.h"
void RCC_Config(void);
void GPIOB_Init(void);
void Config_TIM4(void);
int main(void){
RCC_Config();
GPIOB_Init();
Config_TIM4();
while(1){
}
}
void GPIOB_Init(){
GPIOB->MODER |= 0x8000;
//Sets PB7 as output (Blue led)
GPIOB->AFR[0] |= 0x20000000;
//Sets alternate function on PB7 to 2 TIM4_Ch2
}
void RCC_Config(){
int a;
RCC->AHB1ENR |= 0x02;
//Enables clock for PORTB
RCC->APB1ENR |= 0x04;
//Enables clock for TIM4
a = RCC->AHB1ENR;
//Small delay
}
void Config_TIM4(void){
/* Setting frequency:
*
* PWM frequency = 1KHz
* PWM Steps = 500 OR 0x1F4
*
* Counter_Freq = 1KHz * 500
* Counter_Freq = 500KHz
*
* Prescaler = (16MHz / 500KHz)-1
* Prescaler = 31 OR 0x1F
*
* DutyCycle = 50%
* TIM4->CCR1 = 50% * 500
* TIM4->CCR1 = 250 OR 0xFA
*
* */
TIM4->ARR = 0x1F4;
//PWM Steps = 500
TIM4->PSC = 0x1F;
//Prescaler = 31
TIM4->CCMR1 |= 0x00007000;
//Sets the PWM mode to 2 (OC2M = 0111) bits 14, 13 and 12
TIM4->CCER |= 0x10;
//Enables the result of CC on the corresponding pin
TIM4->CCR1 = (0xFA);
//Sets the duty cycle, in this case approximately 50%
TIM4->CR1 |= 0x05;
//Enables the counter
}
