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Using GPS as Time Source

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Matthias Prinke edited this page Mar 7, 2026 · 19 revisions

Use Case

BresserWeatherSensorLW's README – Real-Time Clock (RTC) lists several option for setting the microcontroller's internal RTC from a time source:

  • LoRaWAN Network Time
  • LoRaWAN Downlink Command
  • Separate RTC with backup battery

Potential reasons for using a GPS as time source:

  • Time is set automatically
  • Timezone is set automatically
  • High accuracy (no unknown latency as in case of LoRaWAN network time)

Interfacing

Warning

Check the GPS module's datasheet for the correct power supply voltage and I/O voltage levels! Using the wrong voltage can damage the GPS module or the microcontroller.

The following are common GPS module configurations:

  1. 3.3V power supply and 3.3V I/O levels
  2. 5V power supply and 3.3V I/O levels (internal voltage regulator)
  3. 5V power supply and 5V I/O levels (LEVEL SHIFTER REQUIRED!)

Power Management

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