diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/main.c | 91 |
1 files changed, 78 insertions, 13 deletions
@@ -19,6 +19,7 @@ void main(void) { clock_init(); gpio_init(); + gpio_clear(GPIOC, GPIO13); // set onboard LED on nvic_init(); timer_init(); @@ -28,23 +29,47 @@ void main(void) static void clock_init(void) { + // set sysclk to 72 MHz via external 8 MHz crystal rcc_clock_setup_pll(&rcc_hse_configs[RCC_CLOCK_HSE8_72MHZ]); - rcc_periph_clock_enable(RCC_GPIOC); // for PC13 blinking - rcc_periph_clock_enable(RCC_TIM2); // for timer / counter 2 + + // enable clocks for GPIO ports B and C + rcc_periph_clock_enable(RCC_GPIOB); + rcc_periph_clock_enable(RCC_GPIOC); + + // enable clock for timer 2 (blinking) + rcc_periph_clock_enable(RCC_TIM2); + + // enable clock for timer 3 (PWM) + rcc_periph_clock_enable(RCC_TIM3); + + // enable clock for alternate functions + rcc_periph_clock_enable(RCC_AFIO); // TODO is this necessary? } static void gpio_init(void) { - gpio_set_mode(GPIOC, - GPIO_MODE_OUTPUT_50_MHZ, - GPIO_CNF_OUTPUT_PUSHPULL, - GPIO13); + // init PC13 onboard LED for blinking + gpio_set_mode( + GPIOC, + GPIO_MODE_OUTPUT_50_MHZ, + GPIO_CNF_OUTPUT_PUSHPULL, + GPIO13 + ); + + // setup PB0 (connected to TIM3_CH3) for PWM + gpio_set_mode( + GPIOB, + GPIO_MODE_OUTPUT_50_MHZ, + GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, + GPIO_TIM3_CH3 + ); } static void nvic_init(void) { + // enable timer 2 interrupt and set priority nvic_enable_irq(NVIC_TIM2_IRQ); nvic_set_priority(NVIC_TIM2_IRQ, 1); } @@ -52,20 +77,60 @@ static void nvic_init(void) static void timer_init(void) { - // set LED on - gpio_clear(GPIOC, GPIO13); - - // setup timer + // setup timer 2 for blinking timer_set_counter(TIM2, 1); timer_set_prescaler(TIM2, 1440); - timer_set_period(TIM2, 50000); - timer_enable_irq(TIM2, TIM_DIER_UIE); // set action to trigger interrupt + timer_set_period(TIM2, 25000); + + // enable timer / counter 2 and the corresponding interrupt for blinking + timer_enable_irq(TIM2, TIM_DIER_UIE); timer_enable_counter(TIM2); + + /* + enable timer / counter 3 + */ + + /* Clock division and mode */ + TIM3_CR1 = TIM_CR1_CKD_CK_INT | TIM_CR1_CMS_EDGE; + /* Period */ + TIM3_ARR = 65535; + /* Prescaler */ + TIM3_PSC = 0; + TIM3_EGR = TIM_EGR_UG; + + /* ---- */ + /* Output compare 3 mode and preload */ + TIM3_CCMR2 |= TIM_CCMR2_OC3M_PWM1 | TIM_CCMR2_OC3PE; + + /* Polarity and state */ + TIM3_CCER |= TIM_CCER_CC3P | TIM_CCER_CC3E; + //TIM3_CCER |= TIM_CCER_CC3E; + + /* Capture compare value */ + TIM3_CCR3 = 30000; + + /* ---- */ + /* ARR reload enable */ + TIM3_CR1 |= TIM_CR1_ARPE; + + /* Counter enable */ + TIM3_CR1 |= TIM_CR1_CEN; } void tim2_isr(void) { + // PWM handling + static uint32_t pwm_value; + pwm_value += 20000; + if (pwm_value > 60000) { + pwm_value = 0; + } + TIM3_CCR3 = pwm_value; + + // toggle blink LED gpio_toggle(GPIOC, GPIO13); - TIM_SR(TIM2) &= ~TIM_SR_UIF; // clear interrrupt flag + + // clear interrrupt flag + TIM_SR(TIM2) &= ~TIM_SR_UIF; } |