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Referenční manuál, str. 331.
#define PWMPERIOD 100 #define SAMPLE 100 void TIM4_IRQHandler(void) { static uint32_t t = 0; static uint16_t duty = 0; // clear interrupt status if (TIM4->DIER & 0x01) { if (TIM4->SR & 0x01) { TIM4->SR &= ~(1U << 0); } } duty =(uint16_t)(PWMPERIOD/2.0 * (sin(2*M_PI*(double)t/(SAMPLE)) + 1.0)); ++t; if (t == SAMPLE) t = 0; // set new duty cycle TIM4->CCR1 = duty; } int main(void) { // enable GPIOB clock and set alternate function RCC->AHB1ENR |= (1 << 1); GPIOB->MODER |= (0x2 << 12); // pin 6 af mode 10 // Choose Timer4 as Alternative Function for pin 12 GPIOB->AFR[1] |= (0x2 << 24); // enable TIM4 clock (bit2) RCC->APB1ENR |= (1 << 2); // fCK_PSC / (PSC[15:0] + 1) // 84 Mhz / 8399 + 1 = 10 khz timer clock speed TIM4->PSC = 8399; // set period TIM4->ARR = PWMPERIOD; // set duty cycle on channel 1 TIM4->CCR1 = 1; // enable channel 1 in capture/compare register // set oc1 mode as pwm (0b110 or 0x6 in bits 6-4) TIM4->CCMR1 |= (0x6 << 4); // enable oc1 preload bit 3 TIM4->CCMR1 |= (1 << 3); // enable capture/compare ch1 output TIM4->CCER |= (1 << 0); // enable update interrupt TIM4->DIER |= (1 << 0); NVIC_SetPriority(TIM4_IRQn, 2); // Priority level 2 // enable TIM4 IRQ from NVIC NVIC_EnableIRQ(TIM4_IRQn); // Enable Timer 4 module (CEN, bit0) TIM4->CR1 |= (1 << 0); while(1) { // Do nothing. } return 0; }