281 lines
9.1 KiB
C++
281 lines
9.1 KiB
C++
/*
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///--> IMPORTANT LICENSE NOTE for timesync option 1 in 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 for timesync option TIME_SYNC_LORASERVER. The shown
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implementation example is covered by the repository's licencse, but you may not
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be eligible to deploy the applied algorithm in applications without granted
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license by the patent holder.
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You may use timesync option TIME_SYNC_LORAWAN if you do not want or cannot
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accept this.
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*/
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#if (TIME_SYNC_LORASERVER) && (TIME_SYNC_LORAWAN)
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#error Duplicate timesync method selected. You must select either LORASERVER or LORAWAN timesync.
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#endif
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#include "timesync.h"
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// Local logging tag
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static const char TAG[] = __FILE__;
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static bool timeSyncPending = false;
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static uint8_t time_sync_seqNo = (uint8_t)random(TIME_SYNC_MAX_SEQNO),
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sample_idx;
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static uint32_t timesync_timestamp[TIME_SYNC_SAMPLES][no_of_timestamps];
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static TaskHandle_t timeSyncProcTask;
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// create task for timeserver handshake processing, called from main.cpp
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void timesync_init(void) {
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xTaskCreatePinnedToCore(timesync_processReq, // task function
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"timesync_proc", // name of task
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4096, // stack size of task
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(void *)1, // task parameter
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3, // priority of the task
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&timeSyncProcTask, // task handle
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1); // CPU core
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}
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// kickoff asnychronous timesync handshake
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void timesync_request(void) {
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// exit if a timesync handshake is already running
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if (timeSyncPending)
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return;
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// start timesync handshake
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else {
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ESP_LOGI(TAG, "[%0.3f] Timeserver sync request started, seqNo#%d",
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millis() / 1000.0, time_sync_seqNo);
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xTaskNotifyGive(timeSyncProcTask); // unblock timesync task
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}
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}
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// task for processing time sync request
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void IRAM_ATTR timesync_processReq(void *taskparameter) {
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uint32_t rcv_seqNo = TIME_SYNC_END_FLAG;
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uint32_t time_offset_sec = 0, time_offset_ms = 0;
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// this task is an endless loop, waiting in blocked mode, until it is
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// unblocked by timesync_request(). It then waits to be notified from
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// timesync_serverAnswer(), which is called from LMIC each time a timestamp
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// from the timesource via LORAWAN arrived.
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// --- asnychronous part: generate and collect timestamps from gateway ---
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while (1) {
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// wait for kickoff
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ulTaskNotifyTake(pdFALSE, portMAX_DELAY);
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// initialize flag and counters
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timeSyncPending = true;
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time_offset_ms = sample_idx = 0;
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if (++time_sync_seqNo > TIME_SYNC_MAX_SEQNO)
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time_sync_seqNo = 0;
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// wait until we are joined if we are not
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while (!LMIC.devaddr) {
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vTaskDelay(pdMS_TO_TICKS(3000));
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}
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// collect timestamp samples in timestamp array
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for (uint8_t i = 0; i < TIME_SYNC_SAMPLES; i++) {
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// send timesync request
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#if (TIME_SYNC_LORASERVER) // ask user's timeserver (for LoRAWAN < 1.0.3)
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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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#elif (TIME_SYNC_LORAWAN) // ask network (requires LoRAWAN >= 1.0.3)
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LMIC_requestNetworkTime(timesync_serverAnswer, &time_sync_seqNo);
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// trigger to immediately get DevTimeAns from class A device
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LMIC_sendAlive();
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#endif
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// wait until a timestamp was received
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if (xTaskNotifyWait(0x00, ULONG_MAX, &rcv_seqNo,
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pdMS_TO_TICKS(TIME_SYNC_TIMEOUT * 1000)) == pdFALSE) {
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ESP_LOGW(TAG, "[d%0.3f] Timesync aborted: timed out",
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millis() / 1000.0);
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goto Fail; // no timestamp received before timeout
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}
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// check if we are in handshake with server
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if (rcv_seqNo != time_sync_seqNo) {
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ESP_LOGW(TAG, "[%0.3f] Timesync aborted: handshake out of sync",
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millis() / 1000.0);
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goto Fail;
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}
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#if (TIME_SYNC_LORASERVER)
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// calculate time diff with received timestamp
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time_offset_ms += timesync_timestamp[sample_idx][timesync_rx] -
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timesync_timestamp[sample_idx][timesync_tx];
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#endif
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// increment sample index
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sample_idx++;
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// if we are not in last cycle, pause until next cycle
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if (i < TIME_SYNC_SAMPLES - 1)
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vTaskDelay(pdMS_TO_TICKS(TIME_SYNC_CYCLE * 1000));
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} // for i
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// --- time critial part: evaluate timestamps and calculate time ---
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// mask application irq to ensure accurate timing
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mask_user_IRQ();
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// calculate average time offset over the summed up difference
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time_offset_ms /= TIME_SYNC_SAMPLES;
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// take latest timestamp received from gateway
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// and add time difference rounded to whole seconds
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time_offset_sec = timesync_timestamp[sample_idx - 1][gwtime_sec];
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time_offset_sec += time_offset_ms / 1000;
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// add milliseconds from latest gateway time, and apply a compensation
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// constant for processing times on node and gateway, strip full seconds
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time_offset_ms += timesync_timestamp[sample_idx - 1][gwtime_msec];
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time_offset_ms += TIME_SYNC_FIXUP;
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time_offset_ms %= 1000;
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setMyTime(time_offset_sec, time_offset_ms, _lora);
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// send timesync end char to show timesync was successful
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payload.reset();
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payload.addByte(TIME_SYNC_END_FLAG);
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SendPayload(TIMEPORT, prio_high);
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goto Finish;
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Fail:
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// set retry timer
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timesyncer.attach(TIME_SYNC_INTERVAL_RETRY * 60, setTimeSyncIRQ);
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// intentionally fallthrough to Finish here
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Finish:
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// end of time critical section: release app irq lock
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timeSyncPending = false;
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unmask_user_IRQ();
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} // infinite while(1)
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}
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// store incoming timestamps
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void timesync_store(uint32_t timestamp, timesync_t timestamp_type) {
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ESP_LOGD(TAG, "[%0.3f] seq#%d[%d]: t%d=%d", millis() / 1000.0,
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time_sync_seqNo, sample_idx, timestamp_type, timestamp);
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timesync_timestamp[sample_idx][timestamp_type] = timestamp;
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}
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// callback function to receive time answer from network or answer
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void IRAM_ATTR timesync_serverAnswer(void *pUserData, int flag) {
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#if (TIME_SYNC_LORASERVER) || (TIME_SYNC_LORAWAN)
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// if no timesync handshake is pending then exit
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if (!timeSyncPending)
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return;
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// mask application irq to ensure accurate timing
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mask_user_IRQ();
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// return code: 0 = failed / 1 = success
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int rc = 0;
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// cast back void parameter to a pointer
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uint8_t *p = (uint8_t *)pUserData, rcv_seqNo = *p;
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uint16_t timestamp_msec = 0;
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uint32_t timestamp_sec = 0;
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#if (TIME_SYNC_LORASERVER)
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// pUserData: contains pointer (32bit) to payload buffer
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// flag: length of buffer
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// Store the instant the time request of the node was received on the gateway
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timesync_store(osticks2ms(os_getTime()), timesync_rx);
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// parse pUserData:
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// p type meaning
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// +0 uint8_t sequence number (taken from node's time_sync_req)
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// +1 uint32_t current second (from UTC epoch)
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// +4 uint8_t 1/250ths fractions of current second
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// swap byte order from msb to lsb, note: this is a platform dependent hack
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timestamp_sec = __builtin_bswap32(*(uint32_t *)(++p));
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// one step being 1/250th sec * 1000 = 4msec
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timestamp_msec = *(p += 4) * 4;
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// if no time is available or spurious buffer then exit
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if (flag != TIME_SYNC_FRAME_LENGTH) {
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if (rcv_seqNo == TIME_SYNC_END_FLAG)
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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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goto Exit; // failure
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}
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goto Finish;
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#elif (TIME_SYNC_LORAWAN)
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// pUserData: contains pointer to SeqNo (not needed here)
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// flag: indicates if we got a recent time from the network
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uint32_t delay_msec;
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lmic_time_reference_t lmicTime;
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if (flag != 1) {
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ESP_LOGW(TAG, "[%0.3f] Network did not answer time request",
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millis() / 1000.0);
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goto Exit;
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}
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// Populate lmic_time_reference
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if ((LMIC_getNetworkTimeReference(&lmicTime)) != 1) {
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ESP_LOGW(TAG, "[%0.3f] Network time request failed", millis() / 1000.0);
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goto Exit;
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}
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// Calculate UTCTime, considering the difference between GPS and UTC time
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// epoch, and the leap seconds
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timestamp_sec = lmicTime.tNetwork + GPS_UTC_DIFF;
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// Add the delay between the instant the time was transmitted and
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// the current time
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delay_msec = osticks2ms(os_getTime() - lmicTime.tLocal);
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timestamp_sec += delay_msec / 1000;
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timestamp_msec += delay_msec % 1000;
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goto Finish;
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#endif // (TIME_SYNC_LORAWAN)
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Finish:
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// check if calculated time is recent
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if (timeIsValid(timestamp_sec)) {
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// store time received from gateway
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timesync_store(timestamp_sec, gwtime_sec);
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timesync_store(timestamp_msec, gwtime_msec);
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// success
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rc = 1;
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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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}
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Exit:
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// end of time critical section: release app irq lock
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unmask_user_IRQ();
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// inform processing task
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xTaskNotify(timeSyncProcTask, (rc ? rcv_seqNo : TIME_SYNC_END_FLAG),
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eSetBits);
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#endif // (TIME_SYNC_LORASERVER) || (TIME_SYNC_LORAWAN)
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} |