Bug: T-Echo (nRF52840) on 2.7.15 reports incorrect and quantized GPS positions

[4cnmpj8ry6-ops]

Category

Other

Hardware

T-Echo

Is this bug report about any UI component firmware like InkHUD or Meshtatic UI (MUI)?

• Meshtastic UI aka MUI colorTFT
• InkHUD ePaper
• OLED slide UI on any display

Firmware Version

2.7.15.567b8ea

Description

Hardware:

• LILYGO T-Echo (nRF52840)

Firmware:

• 2.7.15 (commit 567b8ea)

Observed behavior:

• The GPS coordinates shown on the T-Echo e-ink display are wrong by ~200–300 meters (mostly in longitude)
• Multiple different nodes appear at exactly the same coordinates on the Meshtastic map
• This happens even when nodes are physically separated by tens or hundreds of meters
• Position overrides, reboots, and moving the node outside do not change the offset

Additional observation:

• ESP32-based nodes running the same firmware in the same mesh show distinct positions, while multiple T-Echo nodes collapse to the same map location

This looks like a problem in how GPS positions are encoded or transmitted on the nRF52 (T-Echo) platform rather than a reception or multipath issue.

Steps to reproduce:

1. Flash a LILYGO T-Echo with 2.7.15
2. Place two T-Echo nodes 50–200 m apart outdoors
3. Both nodes appear at the same or nearly the same coordinates on the map

Expected:
Each node should show its actual GPS position.

Relevant log output

[github-actions]

@4cnmpj8ry6-ops, Welcome to Meshtastic! 👋

Thanks for opening your first issue. If it's helpful, an easy way
to get logs is the "Open Serial Monitor" button on the Web Flasher.

If you have ideas for features, note that we often debate big ideas
in the discussions tab
first. This tracker tends to be for ideas that have community
consensus and a clear implementation.

We're very active on discord,
especially the #firmware and #alphanauts-testing channels. If you'll
be around for a while, we'd love to see you there!

Welcome to the community! ❤️