[FR] LYWSD02 NTP clock sync

[nonflammable]

Feature request: LYWSD02 internal clock is not precise. After few weeks time can be shitf over minute. A good solution would be to synchronize the time with a NTP server via OMG.

[1technophile]

Good catch, for info Theengs Gateway does it automatically thanks to @koenvervloesem. https://github.com/theengs/gateway

But agreed, could be considered with OMG

[github-actions[bot]]

This issue is stale because it has been open for 30 days with no activity.

[github-actions[bot]]

This issue was closed because it has been inactive for 14 days since being marked as stale.

[netroy]

I'm able to do this using the commands/MQTTtoBT topic with a payload like this

{
  "ble_write_address":"[[LYWSD02 MAC ADDRESS]]",
  "ble_write_service":"ebe0ccb0-7a0a-4b0c-8a1a-6ff2997da3a6",
  "ble_write_char":"ebe0ccb7-7a0a-4b0c-8a1a-6ff2997da3a6",
  "ble_write_value":"09c93f6501",
  "value_type":"HEX",
  "immediate":true
}

I'm calculating the ble_write_value using this JS code in my browser console

(() => {
  const timeZone = 1; // CET
  const buffer = new ArrayBuffer(5);
  new DataView(buffer).setUint32(0, Math.floor(Date.now()/1000), true);
  new DataView(buffer).setUint8(4, timeZone);
  return [...new Uint8Array(buffer)]
    .map(x => x.toString(16).padStart(2, '0'))
    .join('')
})();

So, theoretically it should be possible to add this

1. in main/ZgatewayBT.ino, as a GATT characteristic write right after reading temperature/humidity (which seems too frequent, and seems to drain the battery much quicker), or
2. as a button using createDiscovery("button" in main/ZmqttDiscovery.ino to let users press a button to trigger the sync via mqtt, or
3. somehow add keep track of all clocks that need syncing, and then sync them in syncNTP once every day or so.

[nonflammable]

bash version:

timestamp=`date +%s|xargs printf %x`
czas=$(printf %s "$timestamp" | dd conv=swab 2> /dev/null | rev)

mosquitto_pub -t home/OpenMQTTGateway/commands/MQTTtoBT -m '{
  "ble_write_address":"AA:BB:CC:DD:EE:FF",
  "ble_write_service":"ebe0ccb0-7a0a-4b0c-8a1a-6ff2997da3a6",
  "ble_write_char":"ebe0ccb7-7a0a-4b0c-8a1a-6ff2997da3a6",
  "ble_write_value":"'$czas'01",
  "value_type":"HEX",
  "immediate":true
}'

be sure to change:

MQTT TOPIC: mosquitto_pub -t home/OpenMQTTGateway/commands/MQTTtoBT

MAC: "ble_write_address":"AA:BB:CC:DD:EE:FF"

TIMEZONE: "ble_write_value":"'$czas'01" 01=CET