mirror of https://github.com/rusefi/rusefi-1.git
66 lines
2.0 KiB
C++
66 lines
2.0 KiB
C++
/**
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* @file microsecond_timer_stm32.cpp
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*
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* A single upcounting timer (currently TIM5) is used as a single timebase both for time
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* measurement and event scheduling. This helps reduce jitter by not making another time
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* measurement at the time of scheduling.
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*
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* This implementation only works on stm32 because it sets hardware registers directly.
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* ChibiOS doesn't support using timers in output compare mode, only PMW, so we have to
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* manually configure the timer in outupt compare mode.
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*
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* @date Dec 1, 2020
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* @author Matthew Kennedy, (c) 2012-2020
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*/
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#include "global.h"
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#if EFI_PROD_CODE && HAL_USE_PWM
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#include "port_microsecond_timer.h"
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void portSetHardwareSchedulerTimer(efitick_t nowNt, efitick_t setTimeNt) {
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// This implementation doesn't need the current time, only the target time
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UNUSED(nowNt);
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pwm_lld_enable_channel(&SCHEDULER_PWM_DEVICE, 0, setTimeNt);
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pwmEnableChannelNotificationI(&SCHEDULER_PWM_DEVICE, 0);
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}
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static void hwTimerCallback(PWMDriver*) {
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pwmDisableChannelNotificationI(&SCHEDULER_PWM_DEVICE, 0);
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portMicrosecondTimerCallback();
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}
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static constexpr PWMConfig timerConfig = {
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SCHEDULER_TIMER_FREQ,
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UINT32_MAX, // timer period = 2^32 counts
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nullptr, // No update callback
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{
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{PWM_OUTPUT_DISABLED, hwTimerCallback}, // Channel 0 = timer callback, others unused
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{PWM_OUTPUT_DISABLED, nullptr},
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{PWM_OUTPUT_DISABLED, nullptr},
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{PWM_OUTPUT_DISABLED, nullptr}
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},
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0, // CR1
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0 // CR2
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};
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void portInitMicrosecondTimer() {
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pwmStart(&SCHEDULER_PWM_DEVICE, &timerConfig);
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// ChibiOS doesn't let you configure timers in output compare mode, only PWM mode.
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// We want to be able to set the compare register without waiting for an update event
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// (which would take 358 seconds at 12mhz timer speed), so we have to use normal upcounting
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// output compare mode instead.
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SCHEDULER_TIMER_DEVICE->CCMR1 = STM32_TIM_CCMR1_OC1M(1);
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}
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uint32_t getTimeNowLowerNt() {
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// Using the same timer for measurement and scheduling improves
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// precision and reduces jitter.
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return SCHEDULER_TIMER_DEVICE->CNT;
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}
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#endif // EFI_PROD_CODE
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