Heltec V4 + external GNSS: GPS stays “No Fix” on 1.12.0 (web flasher), reproducible on two devices #1592
Description
First off, I'm new to LoRa and Meshcore. Very happy so far, comms work great. Thanks so much for your work! Just one issue with GPS.
Summary
Two Heltec WiFi LoRa 32 V4 devices (ESP32-S3) with an external GNSS module both stay in GPS status “No Fix” indefinitely on MeshCore heltecv4 1.12.0 flashed via the MeshCore web flasher. Mesh comms works normally.
Hardware / Firmware / Setup
- Board: Heltec WiFi LoRa 32 V4
- Firmware: heltecv4 1.12.0
- Flash method: MeshCore web flasher
- GNSS kit/product: https://amzn.eu/d/0fnf6ojJ
- Location / sky view: outdoors, clear sky, Switzerland
- Reproduces on: 2 separate Heltec V4 devices (same behavior)
Steps to reproduce
- Flash heltecv4 1.12.0 via MeshCore web flasher.
- Pair device; confirm LoRa comms works (it does).
- Enable GPS in settings.
- Leave outside with unobstructed sky view for >30–60 minutes.
- Observe GPS remains “No Fix” (no coordinates).
Observed
- GPS enabled in UI.
- GPS never obtains a fix (stays “No Fix”).
- Happens on two devices.
Expected
- With GPS enabled and clear sky view, GNSS should acquire satellites and produce a fix/coordinates.
Questions
- Is external GNSS on Heltec V4 expected to work in MeshCore 1.12.0?
- If yes: are there required Heltec V4-specific settings (UART pins, baud rate, GPS power/reset/wake pin handling)?
- If support is incomplete: what is the intended support status for Heltec V4 + external GNSS?
Potentially related MeshCore GPS issues (GPS “no fix” / GPS control)
- T-Beam board (repater) - no GPS support: T-Beam board (repater) - no GPS support #1207 resolved itself after a day
- T-Beam GPS Baud rate 9600 vs 115200: T-Beam GPS Baud rate 9600 vs 115200 #1284
Hardware context from Meshtastic (Heltec V4 GPS control differences)
(Separate firmware, included here only as evidence that Heltec V4 GNSS enable/power control differs from earlier boards and can produce “no GPS/no fix” symptoms unless handled explicitly.)
- Meshtastic issue on Heltec V4 GPS_EN polarity/inversion: [Bug]: Heltec V4: GPS_EN polarity inverts when 3rd Party GPS pin is defined meshtastic/firmware#8310
- Reddit thread discussing Heltec V4 GPS behavior (“No GPS Present” due to power control): https://www.reddit.com/r/meshtastic/comments/1odi0z5/getting_gps_working_on_heltec_v4/
- Reddit thread on Heltec V4 GPS pin/power-control differences vs V3: https://www.reddit.com/r/meshtastic/comments/1p7r3tz/heltec_v4_gps_pin/
- Reddit thread (“GPS connected and enabled … but Heltec device …”): https://www.reddit.com/r/meshtastic/comments/1dt5iuj/gps_is_connected_and_enabled_in_app_but_heltec/
Crosspost on r/meshcore: https://www.reddit.com/r/meshcore/s/6W2foGp9MD