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esp8266/modpybrtc: Handle RTC overflow. 

ESP-SDK system_get_rtc_time() returns uint32 and therefore overflow
about every 7:45h.  Let's write the last state of system_get_rtc_time()
in RTC mem and use it to check for overflow. This commit require running
pyb_rtc_get_us_since_2000() at least once within 7 hours to avoid
overflow.
This commit is contained in:
puuu 2016-05-24 22:31:50 +09:00 committed by Damien George
parent 1191ec6a14
commit cafdfb7af3
1 changed files with 21 additions and 6 deletions
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27
esp8266/modpybrtc.c
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@ -53,6 +53,9 @@ STATIC const pyb_rtc_obj_t pyb_rtc_obj = {{&pyb_rtc_type}};
uint32_t pyb_rtc_alarm0_wake; // see MACHINE_WAKE_xxx constants
uint64_t pyb_rtc_alarm0_expiry; // in microseconds
// RTC overflow checking
STATIC uint32_t rtc_last_ticks;
void mp_hal_rtc_init(void) {
uint32_t magic;
@ -67,6 +70,8 @@ void mp_hal_rtc_init(void) {
uint32_t len = 0;
system_rtc_mem_write(MEM_USER_LEN_ADDR, &len, sizeof(len));
}
// system_get_rtc_time() is always 0 after reset/deepsleep
rtc_last_ticks = system_get_rtc_time();
// reset ALARM0 state
pyb_rtc_alarm0_wake = 0;
@ -81,13 +86,11 @@ STATIC mp_obj_t pyb_rtc_make_new(const mp_obj_type_t *type, mp_uint_t n_args, mp
return (mp_obj_t)&pyb_rtc_obj;
}
STATIC uint64_t pyb_rtc_raw_us(uint64_t cal) {
return (system_get_rtc_time() * cal) >> 12;
};
void pyb_rtc_set_us_since_2000(uint64_t nowus) {
uint32_t cal = system_rtc_clock_cali_proc();
int64_t delta = nowus - pyb_rtc_raw_us(cal);
// Save RTC ticks for overflow detection.
rtc_last_ticks = system_get_rtc_time();
int64_t delta = nowus - (((uint64_t)rtc_last_ticks * cal) >> 12);
// As the calibration value jitters quite a bit, to make the
// clock at least somewhat practially usable, we need to store it
@ -98,11 +101,23 @@ void pyb_rtc_set_us_since_2000(uint64_t nowus) {
uint64_t pyb_rtc_get_us_since_2000() {
uint32_t cal;
int64_t delta;
uint32_t rtc_ticks;
system_rtc_mem_read(MEM_CAL_ADDR, &cal, sizeof(cal));
system_rtc_mem_read(MEM_DELTA_ADDR, &delta, sizeof(delta));
return pyb_rtc_raw_us(cal) + delta;
// ESP-SDK system_get_rtc_time() only returns uint32 and therefore
// overflow about every 7:45h. Thus, we have to check for
// overflow and handle it.
rtc_ticks = system_get_rtc_time();
if (rtc_ticks < rtc_last_ticks) {
// Adjust delta because of RTC overflow.
delta += (uint64_t)cal << 20;
system_rtc_mem_write(MEM_DELTA_ADDR, &delta, sizeof(delta));
}
rtc_last_ticks = rtc_ticks;
return (((uint64_t)rtc_ticks * cal) >> 12) + delta;
};
STATIC mp_obj_t pyb_rtc_datetime(mp_uint_t n_args, const mp_obj_t *args) {