Posted on February 20, 2017 at 20:04I am trying to synchronize the RTC of a NUCLEO-L476RG board to a GPS. I am using the 1PPS signal from the GPS to generate a timestamp. I then use the LL_RTC_TIME_Syncronize function to adjust the subsecond counter. I read the subsecond register right after that and I can see the value changes. But each 1PPS time stamp occurs at almost the identical count on the subsecond register. It is not exactly the same, so I know that the timestamp is occurring.
Here is the interrupt routine:
void
TAMP_STAMP_IRQHandler(
void)
{
/* USER CODE BEGIN TAMP_STAMP_IRQn 0 */
/* USER CODE END TAMP_STAMP_IRQn 0 */
/* USER CODE BEGIN TAMP_STAMP_IRQn 1 */
//
printf
('\r\nTime Stamp IRQ Handler\r\n');
/* Get the TimeStamp interrupt source enable status */
if
(LL_RTC_IsEnabledIT_TS(RTC) != 0)
{
/* Get the pending status of the TIMESTAMP Interrupt */
if
(LL_RTC_IsActiveFlag_TS(RTC) != 0)
{
/* TIMESTAMP callback */
TimeStampEvent_Callback();
/* Clear the TIMESTAMP interrupt pending bit */
LL_RTC_ClearFlag_TS(RTC);
}
}
/* Clear the EXTI's Flag for RTC TimeStamp and Tamper */
LL_EXTI_ClearFlag_0_31(LL_EXTI_LINE_19);
/* USER CODE END TAMP_STAMP_IRQn 1 */
}
And here is the callback routine:
void
TimeStampEvent_Callback(
void)
{
uint8_t
byte3;
uint8_t
byte2;
uint8_t
byte1;
uint8_t
byte0;
// WaitForSynchro_RTC();
rtc_sub_seconds = LL_RTC_TS_GetSubSecond(RTC);
urtc_sub_seconds = LL_RTC_TIME_GetSubSecond(RTC);
LL_RTC_DisableWriteProtection(RTC);
LL_RTC_TIME_Synchronize(RTC, LL_RTC_SHIFT_SECOND_ADVANCE, (
uint32_t
)0x10);
WaitForSynchro_RTC();
crtc_sub_seconds = LL_RTC_TIME_GetSubSecond(RTC);
byte3 = (
uint8_t
) ((rtc_sub_seconds >> 24) & 0x000000ff);
byte2 = (
uint8_t
) ((rtc_sub_seconds >> 16) & 0x000000ff);
byte1 = (
uint8_t
) ((rtc_sub_seconds >> 😎 & 0x000000ff);
byte0 = (
uint8_t
) (rtc_sub_seconds & 0x000000ff);
printf
(
'TS
Subseconds
register: 0x%02x%02x%02x%02x\r\n'
,byte3, byte2, byte1, byte0);
byte3 = (
uint8_t
) ((urtc_sub_seconds >> 24) & 0x000000ff);
byte2 = (
uint8_t
) ((urtc_sub_seconds >> 16) & 0x000000ff);
byte1 = (
uint8_t
) ((urtc_sub_seconds >> 😎 & 0x000000ff);
byte0 = (
uint8_t
) (urtc_sub_seconds & 0x000000ff);
printf
(
'Uncorrected
subseconds
register: 0x%02x%02x%02x%02x\r\n'
,byte3, byte2, byte1, byte0);
byte3 = (
uint8_t
) ((crtc_sub_seconds >> 24) & 0x000000ff);
byte2 = (
uint8_t
) ((crtc_sub_seconds >> 16) & 0x000000ff);
byte1 = (
uint8_t
) ((crtc_sub_seconds >> 😎 & 0x000000ff);
byte0 = (
uint8_t
) (crtc_sub_seconds & 0x000000ff);
printf
(
'Corrected
subseconds
register: 0x%02x%02x%02x%02x\r\n'
,byte3, byte2, byte1, byte0);
}
In this version, I am just adjusting the subsecond register by a fixed amount (0x10).
