238 lines
7.8 KiB
C++
238 lines
7.8 KiB
C++
/*
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///--> IMPORTANT LICENSE NOTE for this file <--///
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PLEASE NOTE: There is a patent filed for the time sync algorithm used in the
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code of this file. The shown implementation example is covered by the
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repository's licencse, but you may not be eligible to deploy the applied
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algorithm in applications without granted license by the patent holder.
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*/
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#ifdef TIME_SYNC_TIMESERVER
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#include "timesync.h"
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using namespace std::chrono;
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// Local logging tag
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static const char TAG[] = __FILE__;
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TaskHandle_t timeSyncReqTask;
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static uint8_t time_sync_seqNo = 0;
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static bool lora_time_sync_pending = false;
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typedef std::chrono::system_clock myClock;
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typedef myClock::time_point myClock_timepoint;
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typedef std::chrono::duration<long long int, std::ratio<1, 1000>>
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myClock_msecTick;
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myClock_timepoint time_sync_tx[TIME_SYNC_SAMPLES];
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myClock_timepoint time_sync_rx[TIME_SYNC_SAMPLES];
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// send time request message
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void send_timesync_req() {
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// if a timesync handshake is pending then exit
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if (lora_time_sync_pending) {
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// ESP_LOGI(TAG, "Timeserver sync request already pending");
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return;
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} else {
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ESP_LOGI(TAG, "[%0.3f] Timeserver sync request started", millis() / 1000.0);
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lora_time_sync_pending = true;
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// clear timestamp array
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for (uint8_t i = 0; i < TIME_SYNC_SAMPLES; i++)
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time_sync_tx[i] = time_sync_rx[i] = myClock_timepoint();
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// kick off temporary task for timeserver handshake processing
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if (!timeSyncReqTask)
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xTaskCreatePinnedToCore(process_timesync_req, // task function
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"timesync_req", // name of task
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2048, // stack size of task
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(void *)1, // task parameter
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2, // priority of the task
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&timeSyncReqTask, // task handle
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1); // CPU core
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}
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}
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// task for sending time sync requests
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void process_timesync_req(void *taskparameter) {
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uint8_t k = 0, i = 0;
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uint16_t time_to_set_fraction_msec;
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uint32_t seq_no = 0;
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time_t time_to_set;
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auto time_offset_ms = myClock_msecTick::zero();
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// wait until we are joined
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while (!LMIC.devaddr) {
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vTaskDelay(pdMS_TO_TICKS(2000));
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}
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// enqueue timestamp samples in lora sendqueue
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for (uint8_t i = 0; i < TIME_SYNC_SAMPLES; i++) {
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// wrap around seqNo 0 .. 254
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time_sync_seqNo = (time_sync_seqNo < 255) ? time_sync_seqNo + 1 : 0;
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// send sync request to server
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payload.reset();
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payload.addByte(time_sync_seqNo);
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SendPayload(TIMEPORT, prio_high);
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// process answer, wait for notification from recv_timesync_ans()
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if ((xTaskNotifyWait(0x00, ULONG_MAX, &seq_no,
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pdMS_TO_TICKS(TIME_SYNC_TIMEOUT * 1000)) == pdFALSE) ||
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(seq_no != time_sync_seqNo)) {
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ESP_LOGW(TAG, "[%0.3f] Timeserver error: handshake timed out",
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millis() / 1000.0);
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goto finish;
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} // no valid sequence received before timeout
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else { // calculate time diff from collected timestamps
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k = seq_no % TIME_SYNC_SAMPLES;
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// cumulate timepoint diffs
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time_offset_ms += time_point_cast<milliseconds>(time_sync_rx[k]) -
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time_point_cast<milliseconds>(time_sync_tx[k]);
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if (i < TIME_SYNC_SAMPLES - 1) {
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// wait until next cycle
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vTaskDelay(pdMS_TO_TICKS(TIME_SYNC_CYCLE * 1000));
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} else {
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// send flush to open a receive window for last time_sync_answer
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payload.reset();
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payload.addByte(0x99);
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SendPayload(RCMDPORT, prio_high);
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// Send a alive open a receive window for last time_sync_answer
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// void LMIC_sendAlive();
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}
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}
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} // for
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// average time offset from collected diffs
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time_offset_ms /= TIME_SYNC_SAMPLES;
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// calculate time offset with millisecond precision using time base
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// of LMIC os, since we use LMIC's ostime_t txEnd as tx timestamp
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time_offset_ms += milliseconds(osticks2ms(os_getTime()));
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// apply calibration factor for processing time
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time_offset_ms += milliseconds(TIME_SYNC_FIXUP);
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// calculate absolute time in UTC epoch
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// convert to whole seconds, floor
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time_to_set = (time_t)(time_offset_ms.count() / 1000) + 1;
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// calculate fraction milliseconds
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time_to_set_fraction_msec = (uint16_t)(time_offset_ms.count() % 1000);
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ESP_LOGD(TAG, "[%0.3f] Calculated UTC epoch time: %d.%03d sec",
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millis() / 1000.0, time_to_set, time_to_set_fraction_msec);
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// adjust system time
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if (timeIsValid(time_to_set)) {
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// wait until top of second
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vTaskDelay(pdMS_TO_TICKS(1000 - time_to_set_fraction_msec));
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time_to_set++; // advance time 1 sec wait time
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#if (!defined GPS_INT && !defined RTC_INT)
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// sync esp32 hardware timer based pps to top of second
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timerRestart(ppsIRQ); // reset pps timer
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CLOCKIRQ(); // fire clock pps interrupt
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#elif defined HAS_RTC
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// calibrate RTC and RTC_INT pulse on top of second
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set_rtctime(time_to_set);
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#endif
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setTime(time_to_set); // set the time on top of second
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timeSource = _lora;
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timesyncer.attach(TIME_SYNC_INTERVAL * 60,
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timeSync); // set to regular repeat
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ESP_LOGI(TAG, "[%0.3f] Timesync finished, time was adjusted",
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millis() / 1000.0);
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} else
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ESP_LOGW(TAG, "[%0.3f] Timesync failed, outdated time calculated",
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millis() / 1000.0);
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finish:
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lora_time_sync_pending = false;
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timeSyncReqTask = NULL;
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vTaskDelete(NULL); // end task
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}
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// called from lorawan.cpp after time_sync_req was sent
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void store_time_sync_req(uint32_t t_txEnd_ms) {
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uint8_t k = time_sync_seqNo % TIME_SYNC_SAMPLES;
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time_sync_tx[k] += milliseconds(t_txEnd_ms);
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ESP_LOGD(TAG, "[%0.3f] Timesync request #%d sent at %d.%03d",
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millis() / 1000.0, time_sync_seqNo, t_txEnd_ms / 1000,
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t_txEnd_ms % 1000);
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}
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// process timeserver timestamp answer, called from lorawan.cpp
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int recv_timesync_ans(uint8_t buf[], uint8_t buf_len) {
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// if no timesync handshake is pending or spurious buffer then exit
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if (!lora_time_sync_pending)
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return 0; // failure
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// if no time is available or spurious buffer then exit
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if (buf_len != TIME_SYNC_FRAME_LENGTH) {
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if (buf[0] == 0xff)
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ESP_LOGI(TAG, "[%0.3f] Timeserver error: no confident time available",
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millis() / 1000.0);
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else
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ESP_LOGW(TAG, "[%0.3f] Timeserver error: spurious data received",
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millis() / 1000.0);
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return 0; // failure
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}
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else { // we received a probably valid time frame
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uint8_t seq_no = buf[0], k = seq_no % TIME_SYNC_SAMPLES;
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uint16_t timestamp_msec; // convert 1/250th sec fractions to ms
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uint32_t timestamp_sec;
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// fetch timeserver time from 4 bytes containing the UTC seconds since
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// unix epoch. Octet order is big endian. Casts are necessary, because buf
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// is an array of single byte values, and they might overflow when shifted
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timestamp_sec = ((uint32_t)buf[4]) | (((uint32_t)buf[3]) << 8) |
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(((uint32_t)buf[2]) << 16) | (((uint32_t)buf[1]) << 24);
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// the 5th byte contains the fractional seconds in 2^-8 second steps
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timestamp_msec = 4 * buf[5];
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// construct the timepoint when message was seen on gateway
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time_sync_rx[k] += seconds(timestamp_sec) + milliseconds(timestamp_msec);
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// guess timepoint is recent if newer than code compile date
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if (timeIsValid(myClock::to_time_t(time_sync_rx[k]))) {
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ESP_LOGD(TAG, "[%0.3f] Timesync request #%d rcvd at %d.%03d",
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millis() / 1000.0, seq_no, timestamp_sec, timestamp_msec);
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// inform processing task
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if (timeSyncReqTask)
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xTaskNotify(timeSyncReqTask, seq_no, eSetBits);
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return 1; // success
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} else {
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ESP_LOGW(TAG, "[%0.3f] Timeserver error: outdated time received",
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millis() / 1000.0);
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return 0; // failure
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}
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}
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}
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#endif |