openpilot is an open source driver assistance system. openpilot performs the functions of Automated Lane Centering and Adaptive Cruise Control for over 200 supported car makes and models.
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1.9 KiB

#define PWM_COUNTER_OVERFLOW 2000U // To get ~50kHz
// TODO: Implement for 32-bit timers
void pwm_init(TIM_TypeDef *TIM, uint8_t channel){
// Enable timer and auto-reload
register_set(&(TIM->CR1), TIM_CR1_CEN | TIM_CR1_ARPE, 0x3FU);
// Set channel as PWM mode 1 and enable output
switch(channel){
case 1U:
register_set_bits(&(TIM->CCMR1), (TIM_CCMR1_OC1M_2 | TIM_CCMR1_OC1M_1 | TIM_CCMR1_OC1PE));
register_set_bits(&(TIM->CCER), TIM_CCER_CC1E);
break;
case 2U:
register_set_bits(&(TIM->CCMR1), (TIM_CCMR1_OC2M_2 | TIM_CCMR1_OC2M_1 | TIM_CCMR1_OC2PE));
register_set_bits(&(TIM->CCER), TIM_CCER_CC2E);
break;
case 3U:
register_set_bits(&(TIM->CCMR2), (TIM_CCMR2_OC3M_2 | TIM_CCMR2_OC3M_1 | TIM_CCMR2_OC3PE));
register_set_bits(&(TIM->CCER), TIM_CCER_CC3E);
break;
case 4U:
register_set_bits(&(TIM->CCMR2), (TIM_CCMR2_OC4M_2 | TIM_CCMR2_OC4M_1 | TIM_CCMR2_OC4PE));
register_set_bits(&(TIM->CCER), TIM_CCER_CC4E);
break;
default:
break;
}
// Set max counter value
register_set(&(TIM->ARR), PWM_COUNTER_OVERFLOW, 0xFFFFU);
// Update registers and clear counter
TIM->EGR |= TIM_EGR_UG;
}
void pwm_set(TIM_TypeDef *TIM, uint8_t channel, uint8_t percentage){
uint16_t comp_value = (((uint16_t) percentage * PWM_COUNTER_OVERFLOW) / 100U);
switch(channel){
case 1U:
register_set(&(TIM->CCR1), comp_value, 0xFFFFU);
break;
case 2U:
register_set(&(TIM->CCR2), comp_value, 0xFFFFU);
break;
case 3U:
register_set(&(TIM->CCR3), comp_value, 0xFFFFU);
break;
case 4U:
register_set(&(TIM->CCR4), comp_value, 0xFFFFU);
break;
default:
break;
}
}