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Heltec ESP32 V3 Supported Peripherals

GPS Module​

Introduction​

This informational guide outlines the process of enhancing the Heltec ESP32 V3 board by integrating the GT-U7 GPS Module. The addition of this module provides precise GPS capabilities and a real-time clock (RTC), eliminating the need for WiFi or a smartphone for time tracking. This enhancement is particularly beneficial for the mesh, where tracking the duration since the last seen device is crucial. However, it's important to note that the GPS module increases the power demand of your node. We'll address this by detailing how to incorporate a switch or an NPN 2N2222 transistor into your setup. This enables firmware-controlled power management, conserving battery life without sacrificing functionality.

It is important to note that the GPS module increases the power demand of the node. This guide details the incorporation of a switch or an NPN 2N2222 transistor to enable firmware-controlled power management, conserving battery life without compromising functionality.

Benefits​

  • GPS Capabilities: Provides the node with the ability to determine its location with high precision, which is invaluable for tracking, mapping, and various other applications requiring location data.
  • Real-Time Clock (RTC): Ensures accurate timekeeping on the mesh network without relying on external time sources such as the internet or a connected smartphone.

Power Consumption Considerations​

The GT-U7 module is known for its high power consumption, which can potentially shorten the battery lifespan of the node. To mitigate this, two approaches are recommended:

  • Manual Switch: A simple on/off switch for the GPS module, allowing for manual power management.
  • NPN 2N2222 Transistor: Facilitates automatic power control through the firmware, enabling the device to turn off the GPS module based on specific conditions or after a set period.

Materials Needed​

  • Heltec ESP32 V3 board
  • GT-U7 GPS Module
  • NPN 2N2222 Transistor
  • Wires and soldering equipment
  • (Optional) Switch for manual power control

Instructions​

  1. Solder a cable from the TXD slot on the GPS module to GPIO 48 on Heltec board. (You may choose your own GPIO pin)
  2. Solder a cable from the RXD slot on the GPS module to GPIO 47 on Heltec board. (You may choose your own GPIO pin)
  3. Solder a cable from the GND slot on the GPS module to GND pin on Heltec board.
  4. Solder a cable from left leg of NPN 2N2222 Transistor to VCC skit on GPS module.
  5. Solder a cable from Right leg of NPN 2N2222 Transistor to 3V/5V pin on Heltec board.
  6. Solder a cable from Middle leg of NPN 2N2222 Transistor to GPIO 48 of Heltec board. (You may choose your own GPIO pin)
  7. Go to Meshtastic app > Radio Configurations > Position
  8. Set GPS_RX_PIN to 48 (This will communicate to the TXD slot on the GPS)
  9. Set GPS_TX_PIN to 47 (This will communicate to the RXD slot on the GPS)
  10. Set PIN_GPS_EN to 46 (This will allow the meshtastic firmware to turn off the power on the GPS board with the user button of the Heltec Board by pressing it 3 times)

Wiring Diagram​

HeltecESP32V3-gps-module

Troubleshooting Tips​

If the GPS module does not power on, check the connections to the transistor and ensure that the middle pin is properly configured in the firmware settings. If the message "GPS is Disabled" appears, press the user button on the Heltec board three times to enable it. If the message "No GPS Present" appears, check that the TXD and RXD are correctly configured. If the message "No GPS Lock" appears, move the node to another location with access to the sky for a bit to lock on properly. If the location is not accurate, walk around to allow the GPS to properly lock on.

Conclusion​

By following this guide, you can enhance your Heltec ESP32 V3 board with valuable GPS capabilities and an RTC, while effectively managing power consumption. Whether for a hobby project or a more serious application, these additions significantly expand the potential of your device.