diff --git a/components/esp32/esp_timer_esp32.c b/components/esp32/esp_timer_esp32.c index e2d271186..f05f491af 100644 --- a/components/esp32/esp_timer_esp32.c +++ b/components/esp32/esp_timer_esp32.c @@ -113,6 +113,13 @@ static uint32_t s_timer_us_per_overflow; // will not increment s_time_base_us if this flag is set. static bool s_mask_overflow; +//The timer_overflow_happened read alarm register to tell if overflow happened. +//However, there is a monent that overflow happens, and before ISR function called +//alarm register is set to another value, then you call timer_overflow_happened, +//it will return false. +//So we store the overflow value when new alarm is to be set. +static bool s_overflow_happened; + #ifdef CONFIG_PM_DFS_USE_RTC_TIMER_REF // If DFS is enabled, upon the first frequency change this value is set to the // difference between esp_timer value and RTC timer value. On every subsequent @@ -125,12 +132,19 @@ static uint64_t s_rtc_time_diff = 0; // registers. portMUX_TYPE s_time_update_lock = portMUX_INITIALIZER_UNLOCKED; +#define TIMER_BEFORE(a, b) ((int)((uint32_t)(a) - (uint32_t)(b)) < 0) + // Check if timer overflow has happened (but was not handled by ISR yet) static inline bool IRAM_ATTR timer_overflow_happened() { + if (s_overflow_happened) { + return true; + } + return (REG_READ(FRC_TIMER_CTRL_REG(1)) & FRC_TIMER_INT_STATUS) != 0 && - REG_READ(FRC_TIMER_ALARM_REG(1)) == ALARM_OVERFLOW_VAL && - !s_mask_overflow; + ((REG_READ(FRC_TIMER_ALARM_REG(1)) == ALARM_OVERFLOW_VAL && !s_mask_overflow) || + (TIMER_BEFORE(REG_READ(FRC_TIMER_ALARM_REG(1)), ALARM_OVERFLOW_VAL) && + TIMER_BEFORE(ALARM_OVERFLOW_VAL, REG_READ(FRC_TIMER_COUNT_REG(1))))); } uint64_t IRAM_ATTR esp_timer_impl_get_time() @@ -173,25 +187,35 @@ void IRAM_ATTR esp_timer_impl_set_alarm(uint64_t timestamp) uint64_t time_after_timebase_us = timestamp - s_time_base_us; // Adjust current time if overflow has happened bool overflow = timer_overflow_happened(); + uint64_t cur_count = REG_READ(FRC_TIMER_COUNT_REG(1)); + uint32_t offset = s_timer_ticks_per_us; + + //If overflow is going to happen in 1us, let's wait until it happens, + //else we think it will not happen before new alarm set. + //And we should wait current timer count less than ALARM_OVERFLOW_VAL, + //maybe equals to 0. + if (cur_count + offset >= ALARM_OVERFLOW_VAL) { + do { + overflow = timer_overflow_happened(); + cur_count = REG_READ(FRC_TIMER_COUNT_REG(1)); + } while(!overflow || cur_count >= ALARM_OVERFLOW_VAL); + } + if (overflow) { assert(time_after_timebase_us > s_timer_us_per_overflow); time_after_timebase_us -= s_timer_us_per_overflow; + s_overflow_happened = true; } // Calculate desired timer compare value (may exceed 2^32-1) uint64_t compare_val = time_after_timebase_us * s_timer_ticks_per_us; uint32_t alarm_reg_val = ALARM_OVERFLOW_VAL; // Use calculated alarm value if it is less than 2^32-1 if (compare_val < ALARM_OVERFLOW_VAL) { - uint64_t cur_count = REG_READ(FRC_TIMER_COUNT_REG(1)); // If we by the time we update ALARM_REG, COUNT_REG value is higher, // interrupt will not happen for another 2^32 timer ticks, so need to // check if alarm value is too close in the future (e.g. <1 us away). - uint32_t offset = s_timer_ticks_per_us; if (compare_val < cur_count + offset) { compare_val = cur_count + offset; - if (compare_val > UINT32_MAX) { - compare_val = ALARM_OVERFLOW_VAL; - } } alarm_reg_val = (uint32_t) compare_val; } @@ -205,6 +229,7 @@ static void IRAM_ATTR timer_alarm_isr(void *arg) // Timekeeping: adjust s_time_base_us if counter has passed ALARM_OVERFLOW_VAL if (timer_overflow_happened()) { s_time_base_us += s_timer_us_per_overflow; + s_overflow_happened = false; } s_mask_overflow = false; // Clear interrupt status