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Docs Hardware & Components NEO-6M GPS Module Guide

NEO-6M GPS Module Guide

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Choosing, wiring and placing the NEO-6M: UART2, patch antenna, and the RTC RAM backup role

NEO-6M GPS Module Guide

Overview

The NEO-6M is an inexpensive GPS module that reports position over a 9600 baud UART. In the Aegis-Beacon it feeds coordinates into the Morse payload, so rescuers can home in on both the signal and a precise location.

Module Facts

ParameterValue
Chipu-blox NEO-6M
InterfaceUART, 9600 baud
ESP32 portSerial2 (GPIO 22 RX, TX unconnected)
AntennaCeramic patch, onboard
Time to first fix~30 s hot, up to 3 min cold
Minimum satellites3
Fix timeout (firmware)10-120 s, default 30 s

Wiring

GPS pinESP32 GPIONotes
VCC3V3Most modules accept 3.3-5 V
GNDGNDCommon ground
TXGPIO 22GPS TX to ESP32 RX (input-only)
RXN/Cunconnected - firmware never sends to the GPS

The NEO-6M TX line is 3.3 V logic on most breakouts. If your module is a 5 V version, level-shift the TX line before it reaches GPIO 22.

Patch Antenna Placement

The ceramic patch needs sky view. Two rules matter:

  1. Keep the patch away from the ESP32 antenna area and the radio SMA.
  2. Face the patch upward, with metal below it if possible (a small ground plane improves reception).

See GPS Antenna Placement for the full treatment.

The Backup Battery Question

Some NEO-6M boards include a coin-cell holder for RTC backup. The Aegis-Beacon does not depend on it: the last fix is stored in the ESP32 RTC RAM instead, and survives deep sleep and power cycles. A missing backup cell on a clone module is therefore not a problem.

When GPS Is Optional

The firmware runs perfectly with no GPS fitted:

  • Set gpsen to false (default).
  • Payloads degrade gracefully: SOS or SOS DE [NAME] only.
  • Boot skips the GPS wait screen entirely.