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fix subticks handling

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This commit is contained in:
Dan Halbert 2023-05-12 14:39:57 -04:00
parent 0b2f857542
commit e8067851f5
2 changed files with 38 additions and 11 deletions
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47
ports/stm/peripherals/rtc.c
View File

@ -32,7 +32,9 @@
#include "shared/timeutils/timeutils.h"
// Default period for ticks is 1/1024 second
#define TICK_DIVISOR 1024
#define TICKS_PER_SECOND 1024
// Based on a 32768 kHz clock
#define SUBTICKS_PER_TICK 32
STATIC RTC_HandleTypeDef hrtc;
@ -51,6 +53,8 @@ volatile uint32_t cached_hours_minutes = 0;
// If the RTC is set to a later time, the ticks the RTC returns will be offset by the new time.
// Remember that offset so it can be removed when returning a monotonic tick count.
static int64_t rtc_ticks_offset;
// Normalized to be 0-31 inclusive, so always positive.
static uint8_t rtc_subticks_offset;
volatile bool alarmed_already[2];
@ -65,6 +69,7 @@ uint32_t stm32_peripherals_get_rtc_freq(void) {
void stm32_peripherals_rtc_init(void) {
rtc_ticks_offset = 0;
rtc_subticks_offset = 0;
// RTC oscillator selection is handled in peripherals/<family>/<line>/clocks.c
__HAL_RCC_RTC_ENABLE();
@ -124,17 +129,27 @@ STATIC uint64_t stm32_peripherals_rtc_raw_ticks(uint8_t *subticks) {
uint8_t seconds = (uint8_t)(time & (RTC_TR_ST | RTC_TR_SU));
seconds = (uint8_t)RTC_Bcd2ToByte(seconds);
if (subticks != NULL) {
*subticks = subseconds % 32;
*subticks = subseconds % SUBTICKS_PER_TICK;
}
uint64_t raw_ticks = ((uint64_t)TICK_DIVISOR) * (seconds_to_date + seconds_to_minute + seconds) + subseconds / 32;
uint64_t raw_ticks = ((uint64_t)TICKS_PER_SECOND) * (seconds_to_date + seconds_to_minute + seconds) + subseconds / SUBTICKS_PER_TICK;
return raw_ticks;
}
// This function returns monotonically increasing ticks by adjusting away the RTC tick offset
// from the last time the date was set.
uint64_t stm32_peripherals_rtc_monotonic_ticks(uint8_t *subticks) {
return stm32_peripherals_rtc_raw_ticks(subticks) - rtc_ticks_offset;
uint8_t raw_subticks;
uint64_t monotonic_ticks = stm32_peripherals_rtc_raw_ticks(&raw_subticks) - rtc_ticks_offset;
int8_t monotonic_subticks = raw_subticks - rtc_subticks_offset;
// Difference might be negative. Normalize to 0-31.
// `while` not really necessary; should only loop 0 or 1 times.
while (monotonic_subticks < 0) {
monotonic_ticks--;
monotonic_subticks += SUBTICKS_PER_TICK;
}
*subticks = (uint8_t)monotonic_subticks;
return monotonic_ticks;
}
#if CIRCUITPY_RTC
@ -160,8 +175,10 @@ void stm32_peripherals_rtc_set_time(timeutils_struct_time_t *tm) {
RTC_DateTypeDef date = {0};
RTC_TimeTypeDef time = {0};
uint64_t current_monotonic_ticks = stm32_peripherals_rtc_monotonic_ticks(NULL);
uint8_t current_monotonic_subticks;
uint64_t current_monotonic_ticks = stm32_peripherals_rtc_monotonic_ticks(&current_monotonic_subticks);
// SubSeconds will always be set to zero.
time.Hours = tm->tm_hour;
time.Minutes = tm->tm_min;
time.Seconds = tm->tm_sec;
@ -177,8 +194,16 @@ void stm32_peripherals_rtc_set_time(timeutils_struct_time_t *tm) {
// todo - throw an exception
}
rtc_ticks_offset = stm32_peripherals_rtc_raw_ticks(NULL) - current_monotonic_ticks;
;
uint8_t raw_subticks;
rtc_ticks_offset = stm32_peripherals_rtc_raw_ticks(&raw_subticks) - current_monotonic_ticks;
int8_t rtc_subticks_offset_signed = raw_subticks - current_monotonic_subticks;
// Difference might be negative. Normalize subticks to 0-31.
// `while` not really necessary; should only loop 0 or 1 times.
while (rtc_subticks_offset_signed < 0) {
rtc_ticks_offset--;
rtc_subticks_offset_signed += SUBTICKS_PER_TICK;
}
rtc_subticks_offset = (uint8_t)rtc_subticks_offset_signed;
}
#endif
@ -195,7 +220,7 @@ void stm32_peripherals_rtc_set_wakeup_mode_seconds(uint32_t seconds) {
}
void stm32_peripherals_rtc_set_wakeup_mode_tick(void) {
HAL_RTCEx_SetWakeUpTimer_IT(&hrtc, (rtc_clock_frequency / 16) / TICK_DIVISOR, RTC_WAKEUPCLOCK_RTCCLK_DIV2);
HAL_RTCEx_SetWakeUpTimer_IT(&hrtc, (rtc_clock_frequency / 16) / TICKS_PER_SECOND, RTC_WAKEUPCLOCK_RTCCLK_DIV2);
}
void stm32_peripherals_rtc_enable_wakeup_timer(void) {
@ -223,9 +248,9 @@ void stm32_peripherals_rtc_set_alarm(uint8_t alarm_idx, uint32_t ticks) {
uint64_t raw_ticks = stm32_peripherals_rtc_raw_ticks(NULL) + ticks;
RTC_AlarmTypeDef alarm;
if (ticks > TICK_DIVISOR) {
if (ticks > TICKS_PER_SECOND) {
timeutils_struct_time_t tm;
timeutils_seconds_since_2000_to_struct_time(raw_ticks / TICK_DIVISOR, &tm);
timeutils_seconds_since_2000_to_struct_time(raw_ticks / TICKS_PER_SECOND, &tm);
alarm.AlarmTime.Hours = tm.tm_hour;
alarm.AlarmTime.Minutes = tm.tm_min;
alarm.AlarmTime.Seconds = tm.tm_sec;
@ -239,7 +264,7 @@ void stm32_peripherals_rtc_set_alarm(uint8_t alarm_idx, uint32_t ticks) {
}
alarm.AlarmTime.SubSeconds = rtc_clock_frequency - 1 -
((raw_ticks % TICK_DIVISOR) * 32);
((raw_ticks % TICKS_PER_SECOND) * SUBTICKS_PER_TICK);
if (alarm.AlarmTime.SubSeconds > rtc_clock_frequency) {
alarm.AlarmTime.SubSeconds = alarm.AlarmTime.SubSeconds +
rtc_clock_frequency;

2
shared-module/time/__init__.c
View File

@ -38,6 +38,8 @@ uint64_t common_hal_time_monotonic_ns(void) {
uint64_t ticks = port_get_raw_ticks(&subticks);
// A tick is 976562.5 nanoseconds so multiply it by the base and add half instead of doing float
// math.
// A subtick is 1/32 of a tick.
// 30518 is 1e9 / 32768
return 976562 * ticks + ticks / 2 + 30518 * subticks;
}