timeserver (experimental)

include/timesync.h

@@ -5,7 +5,7 @@
 #include "timesync.h"
 #include "timekeeper.h"
 
-#define TIME_SYNC_SAMPLES 1    // number of time requests for averaging
+#define TIME_SYNC_SAMPLES 3   // number of time requests for averaging
 #define TIME_SYNC_CYCLE 30     // seconds between two time requests
 #define TIME_SYNC_TIMEOUT 120  // timeout seconds waiting for timeserver answer
 #define TIME_SYNC_TRIGGER 1.0f // time deviation threshold triggering time sync

src/TTN/Nodered-Timeserver.json

@@ -131,7 +131,7 @@
         "type": "function",
         "z": "449c1517.e25f4c",
         "name": "Time_Sync_Ans",
-        "func": "/* LoRaWAN Timeserver\n\nconstruct 6 byte timesync_answer from gateway timestamp and node's time_sync_req\n\nbyte    meaning\n0       sequence number (taken from node's time_sync_req)\n1..4    current second (from epoch time 1970)\n5       1/250ths fractions of current second\n\n*/\n\n  let buf = new ArrayBuffer(6);\n  let timestamp = (+new Date(msg.payload.metadata.gateways[0].time));\n  \n  var seconds = Math.floor(timestamp/1000);\n  var fractions = timestamp % 250;\n  var seqno = msg.payload.payload_raw[0];\n\n  new DataView(buf).setUint8(0, seqno);\n  new DataView(buf).setUint32(1, seconds);\n  new DataView(buf).setUint8(5, fractions);\n\n  msg.payload = new Buffer(new Uint8Array(buf));\n  \n  return msg;",
+        "func": "/* LoRaWAN Timeserver\n\nconstruct 6 byte timesync_answer from gateway timestamp and node's time_sync_req\n\nbyte    meaning\n0       sequence number (taken from node's time_sync_req)\n1..4    current second (from epoch time 1970)\n5       1/250ths fractions of current second\n\n*/\n\n  let buf = new ArrayBuffer(6);\n  let timestamp = (+new Date(msg.payload.metadata.gateways[0].time));\n  \n  var seconds = Math.floor(timestamp/1000);\n  var fractions = (timestamp % 1000) / 4;\n  var seqno = msg.payload.payload_raw[0];\n\n  new DataView(buf).setUint8(0, seqno);\n  new DataView(buf).setUint32(1, seconds);\n  new DataView(buf).setUint8(5, fractions);\n\n  msg.payload = new Buffer(new Uint8Array(buf));\n  \n  return msg;",
         "outputs": 1,
         "noerr": 0,
         "x": 400,

src/timesync.cpp

@@ -19,8 +19,8 @@ static const char TAG[] = __FILE__;
 TaskHandle_t timeSyncReqTask;
 time_sync_message_t time_sync_messages[TIME_SYNC_SAMPLES] = {0},
                     time_sync_answers[TIME_SYNC_SAMPLES] = {0};
-uint8_t time_sync_seqNo = 0;
+static uint8_t time_sync_seqNo = 0;
-bool time_sync_pending = false;
+static bool time_sync_pending = false;
 
 // send time request message
 void send_Servertime_req() {
@@ -59,15 +59,18 @@ void recv_Servertime_ans(uint8_t buf[], uint8_t buf_len) {
   if ((!time_sync_pending) || (buf_len != TIME_SYNC_FRAME_LENGTH))
     return;
 
-  uint8_t seq_no = buf[0];
+  uint8_t seq_no = buf[0], k = seq_no % TIME_SYNC_SAMPLES;
-  uint32_t timestamp_sec = 0, timestamp_ms = 0;
+  uint32_t timestamp_sec = 0;
 
-  for (uint8_t i = 1; i <= 4; i++)
+  for (uint8_t i = 1; i <= 4; i++) {
-    time_sync_answers[seq_no].seconds = (timestamp_sec <<= 8) |= buf[i];
+    time_sync_answers[k].seconds = (timestamp_sec <<= 8) |= buf[i];
-  time_sync_answers[seq_no].fractions = timestamp_ms = 4 * buf[5];
+  }
+  time_sync_answers[k].fractions = buf[5];
 
-  ESP_LOGD(TAG, "Timeserver answer #%d received: timestamp=%d.%03d", seq_no,
+  ESP_LOGD(TAG, "Timeserver answer:");
-           timestamp_sec, timestamp_ms);
+
+  ESP_LOGD(TAG, "ans.sec(%d)=%d / ans.ms(%d)=%d", k,
+           time_sync_answers[k].seconds, k, time_sync_answers[k].fractions);
 
   // inform processing task
   if (timeSyncReqTask)
@@ -77,11 +80,10 @@ void recv_Servertime_ans(uint8_t buf[], uint8_t buf_len) {
 // task for sending time sync requests
 void process_Servertime_sync_req(void *taskparameter) {
 
-  time_t time_to_set = 0;
+  time_t t = 0, time_to_set = 0;
-  uint32_t seq_no = 0;
+  uint32_t seq_no = 0, k = 0;
-  int16_t time_diff_ms = 0;
+  int time_diff_frac = 0, time_diff_ms = 0;
-  int64_t time_diff_sec = 0;
+  long time_diff_sec = 0, time_offset = 0;
-  float time_offset = 0.0f;
 
   // enqueue timestamp samples in lora sendqueue
   for (uint8_t i = 1; i <= TIME_SYNC_SAMPLES; i++) {
@@ -94,10 +96,12 @@ void process_Servertime_sync_req(void *taskparameter) {
     payload.addByte(time_sync_seqNo);
     SendPayload(TIMEPORT, prio_high);
 
+    /* -> do we really need this? maybe for SF9 up?
     // send dummy packet to trigger receive answer
-    //payload.reset();
+    payload.reset();
-    //payload.addByte(0x99);           // flush
+    payload.addByte(0x99);           // flush
-    //SendPayload(RCMDPORT, prio_low); // to open receive slot for answer
+    SendPayload(RCMDPORT, prio_low); // to open receive slot for answer
+    */
 
     // process answer
     if ((xTaskNotifyWait(0x00, ULONG_MAX, &seq_no,
@@ -109,20 +113,29 @@ void process_Servertime_sync_req(void *taskparameter) {
     } // no valid sequence received before timeout
 
     else { // calculate time diff from set of collected timestamps
-      uint8_t k = seq_no % TIME_SYNC_SAMPLES;
+
+      k = seq_no % TIME_SYNC_SAMPLES;
+
       time_diff_sec +=
-          (time_sync_messages[k].seconds - time_sync_answers[k].seconds);
+          ((time_sync_messages[k].seconds - time_sync_answers[k].seconds) / TIME_SYNC_SAMPLES);
-      time_diff_ms += (4 * (time_sync_messages[k].fractions -
+
-                            time_sync_answers[k].fractions));
+      time_diff_frac +=
+          ((time_sync_messages[k].fractions - time_sync_answers[k].fractions) / TIME_SYNC_SAMPLES);
+
+      ESP_LOGD(TAG, "time_diff_sec=%d / time_diff_frac=%d", time_diff_sec,
+               time_diff_frac);
     }
   } // for
 
   // calculate time offset and set time if necessary
-  time_offset = (time_diff_sec + time_diff_ms / 1000.0f) / TIME_SYNC_SAMPLES;
+  time_diff_ms = 4 * time_diff_frac;
-  ESP_LOGD(TAG, "Timesync time offset=%.3f", time_offset);
+  time_offset = (time_diff_sec + (long) (time_diff_ms / 1000));
-  ESP_LOGD(TAG, "Timesync time_diff_ms=%03d", time_diff_ms);
 
-  if (time_offset >= TIME_SYNC_TRIGGER) {
+  ESP_LOGD(TAG, "Timesync time offset=%d", time_offset);
+
+  t = now();
+
+  if (labs(time_offset) >= (t + TIME_SYNC_TRIGGER)) {
     // wait until top of second
     if (time_diff_ms > 0) // clock is fast
       vTaskDelay(pdMS_TO_TICKS(time_diff_ms));
@@ -130,8 +143,8 @@ void process_Servertime_sync_req(void *taskparameter) {
       vTaskDelay(pdMS_TO_TICKS(1000 + time_diff_ms));
 
     time_diff_sec++;
-    time_to_set = time_t(now() + time_diff_sec);
+    time_to_set = t - time_t(time_diff_sec);
-    ESP_LOGD(TAG, "Time to set = %d", time_to_set);
+    ESP_LOGD(TAG, "Now()=%d, Time to set = %d", t, time_to_set);
 
     // adjust system time
     if (timeIsValid(time_to_set)) {
@@ -156,8 +169,9 @@ finish:
 // called from lorawan.cpp after time_sync_req was sent
 void store_time_sync_req(time_t secs, uint32_t micros) {
   uint8_t k = time_sync_seqNo % TIME_SYNC_SAMPLES;
-  time_sync_messages[k].seconds = secs;
+
-  time_sync_messages[k].fractions = micros / 250; // 4ms resolution
+  time_sync_messages[k].seconds = (uint32_t) secs;
+  time_sync_messages[k].fractions = (uint8_t) (micros / 4000); // 4ms resolution
 
   ESP_LOGD(TAG, "Timeserver request #%d sent at %d.%03d", time_sync_seqNo,
            time_sync_messages[k].seconds, time_sync_messages[k].fractions);