Posted on October 08, 2012 at 05:20I can get PWM output to work with my F4 MCUs, but I can't get it to work with the F0. My code is below, any ideas? As you can see, I'm not using the STM libraries, I am only using their stm32f0xx.h header for register definitions.
#include ''stm32f0xx.h''
#include ''core_cm0.h''
void TIM1_BRK_UP_TRG_COM_IRQHandler(); // ISR prototype
int main() {
RCC->AHBENR |= RCC_AHBENR_GPIOAEN; // Enable GPIOA clock
GPIOA->MODER |= GPIO_MODER_MODER8_1; // Pin A8 mode = Alt Function
GPIOA->AFR[1] |= 0b0010; // Pin A8 alt function = AF2 (TIM1)
GPIOA->OSPEEDR |= GPIO_OSPEEDER_OSPEEDR8; // Pin A8 speed = 50MHz
RCC->APB2ENR |= RCC_APB2ENR_TIM1EN; // Enable clock
TIM1->PSC = 23; // Prescaler = 23 (1 tick per half microsecond)
TIM1->ARR = 19999; // Auto-reload = PWM frequency in half microseconds = 10ms period
TIM1->CCMR1 |= TIM_CCMR1_OC1M_1 | TIM_CCMR1_OC1M_2; // OC1M = 110 for PWM Mode 1 output on ch1
TIM1->CCMR1 |= TIM_CCMR1_OC1PE; // Output 1 preload enable
TIM1->CR1 |= TIM_CR1_ARPE; // Auto-reload preload enable
TIM1->CCER |= TIM_CCER_CC1E; // Enable output for ch1
TIM1->CCR1 = 1800; // CCR1 = Duty cycle in half microseconds = high for 900us
TIM1->EGR |= TIM_EGR_UG; // Force update
TIM1->SR &= ~TIM_SR_UIF; // Clear the update flag
TIM1->DIER |= TIM_DIER_UIE; // Enable interrupt on update event
NVIC_EnableIRQ(TIM1_BRK_UP_TRG_COM_IRQn); // Enable IRQ
TIM1->CR1 |= TIM_CR1_CEN; // Enable counter
while(1) {
}
}
void TIM1_BRK_UP_TRG_COM_IRQHandler() {
if(TIM1->SR & TIM_SR_UIF != 0) { // If update flag is set
// do stuff here if needed
}
TIM1->SR &= ~TIM_SR_UIF; // Interrupt has been handled
}
