gnss-gps-integration
starsforks
How to install gnss-gps-integration?
easyzoom/aix-skills/gnss-gps-integration
$npx -y skills add easyzoom/aix-skills --skill gnss-gps-integrationUse when integrating a UART GNSS/GPS module (u-blox M8/M9/M10, Quectel Lxx), parsing NMEA GGA/RMC/GSA/GSV or UBX-NAV-PVT, or debugging no-fix, TTFF, checksum, or PPS issues
SKILL.md
| 1 | # GNSS GPS Integration |
| 2 | |
| 3 | ## Overview |
| 4 | |
| 5 | Use this skill to connect a GNSS/GPS module to an MCU over UART and turn raw output into a trusted fix. The hard parts are proving the byte stream is intact (NMEA XOR checksum, UBX sync), rejecting invalid fixes, and getting acceptable TTFF given antenna, sky view, and backup-power constraints. |
| 6 | |
| 7 | ## When To Use |
| 8 | |
| 9 | Use this skill when: |
| 10 | |
| 11 | - The user integrates u-blox `NEO-M8N`, `NEO-M9N`, `MAX-M10`, or Quectel `L76`/`L80`/`LC76` over UART. |
| 12 | - The work involves parsing `$GxGGA`, `$GxRMC`, `$GxGSA`, `$GxGSV`, the `*hh` XOR checksum, or the UBX binary protocol (`0xB5 0x62`, `UBX-NAV-PVT`). |
| 13 | - Symptoms include no satellites, TTFF too long, `RMC` status `V`, lat/lon of 0, truncated NMEA frames, or PPS not toggling. |
| 14 | - Configuration uses the legacy `UBX-CFG-PRT`/`UBX-CFG-MSG` messages (M8-era), the config-key interface `UBX-CFG-VALSET`/`UBX-CFG-VALGET` (M9/M10), or PMTK sentences (`PMTK251`, `PMTK220`, `PMTK314`). |
| 15 | |
| 16 | Do not use this skill when the UART link itself is unproven; confirm bytes arrive at the correct baud first. |
| 17 | |
| 18 | ## First Questions |
| 19 | |
| 20 | Ask for: |
| 21 | |
| 22 | - Exact module and vendor (u-blox M8/M9/M10 vs Quectel Lxx), since protocol and config differ. |
| 23 | - UART baud (u-blox default `9600`, Quectel L76 default `9600`), wiring (TX/RX crossed, CMOS 3V3 levels). |
| 24 | - Active vs passive antenna, its supply/bias-T, and current sky visibility (indoors vs open sky). |
| 25 | - Backup power: is `V_BCKP`/RTC battery or supercap fitted, or does the module lose power fully each cycle? |
| 26 | - Whether the design needs continuous or low-power periodic fixes, and if PPS time sync is required. |
| 27 | - Current raw output (paste a few NMEA lines) and the observed failure. |
| 28 | |
| 29 | ## Integration Checklist |
| 30 | |
| 31 | 1. Prove the raw stream. |
| 32 | Log UART bytes at the module's default baud before parsing; confirm `$G...` ASCII lines or UBX `0xB5 0x62` frames, not garbage from a baud mismatch. |
| 33 | |
| 34 | 1. Validate every sentence. |
| 35 | Compute the XOR of all chars between `$` and `*`, compare to the two hex digits after `*`, and drop the line on mismatch or missing CR/LF instead of parsing junk. |
| 36 | |
| 37 | 1. Gate on the fix flag. |
| 38 | Trust position only when `RMC` status is `A` (not `V`) and `GGA` fix quality is nonzero; treat lat/lon `0,0` as no-fix, and read satellite count/HDOP from `GGA`, sats-in-view from `GSV`. |
| 39 | |
| 40 | 1. Configure output intentionally. |
| 41 | On u-blox M8 use the legacy `UBX-CFG-PRT` (baud/protocols) and `UBX-CFG-MSG` (per-message rate); on M9/M10 use the config-key interface `UBX-CFG-VALSET`/`UBX-CFG-VALGET`, since the legacy `CFG-*` messages are deprecated there. Poll or enable `UBX-NAV-PVT` for a binary fix. On Quectel/MTK use `PMTK314` (sentence selection), `PMTK220` (update rate), `PMTK251` (baud). Save config if the module supports it. |
| 42 | |
| 43 | 1. Handle startup and backup power. |
| 44 | Expect cold start (~30 s to minutes) when ephemeris is lost; keep `V_BCKP`/RTC powered so warm/hot starts (seconds) work. Issuing a cold start (`PMTK103`) or a full cold start (`PMTK104`, which also clears config) clears aiding data and forces a long TTFF. |
| 45 | |
| 46 | 1. Wire PPS and low-power correctly. |
| 47 | If timing matters, latch the PPS edge in an ISR and pair it with the time from `RMC`/`UBX-NAV-PVT`; for periodic duty cycling, allow re-acquisition time and avoid killing backup power between wakeups. |
| 48 | |
| 49 | ## Common Failures |
| 50 | |
| 51 | - No satellites: passive antenna with no bias voltage, antenna indoors/blocked, or open/short on the active-antenna feed (no current = open, excess = short). |
| 52 | - Baud mismatch: reading a `115200` module at `9600` yields framing errors and random bytes. |
| 53 | - Checksum failures or truncated lines: undersized RX buffer, UART overrun, or parsing before a full `\r\n` line arrives. |
| 54 | - Every fix is a cold start (long TTFF): `V_BCKP`/RTC unpowered, so ephemeris/almanac are lost on each power cycle. |
| 55 | - Position stuck at `0,0` or status `V`: parser ignores the validity flag and publishes an unfixed solution. |
| 56 | - UBX ignored: wrong sync bytes, class/ID, or a mis-computed 8-bit Fletcher checksum (`CK_A`/`CK_B`) on the `CFG` message. |
| 57 | |
| 58 | ## Verification |
| 59 | |
| 60 | Before claiming the GNSS link works: |
| 61 | |
| 62 | - State module, baud, antenna type/power, and protocol (NMEA and/or UBX). |
| 63 | - Show a captured sentence with a checksum you recomputed and confirmed. |
| 64 | - Confirm a real fix: `RMC` status `A`, nonzero `GGA` quality, plausible lat/lon, sat count and HDOP. |
| 65 | - Report measured TTFF from cold and from warm/hot start, and confirm backup power behavior. |
| 66 | - If used, confirm PPS toggles at 1 Hz and aligns with the reported time. |
| 67 | |
| 68 | ## Example |
| 69 | |
| 70 | User: |
| 71 | |
| 72 | ```text |
| 73 | NEO-M8N 接上了,UART 有数据,但一直定位不了,$GNRMC 的状态一直是 V。 |
| 74 | ``` |
| 75 | |
| 76 | Agent: |
| 77 | |
| 78 | 1. Confirms baud (`9600` default) and captures a few raw lines to verify checksums pass and sentences are complete. |
| 79 | 1. Reads `GGA` fix quality and `GSV` sats-in-view; asks about antenna type/power and wheth |
People who liked this also viewed
6 picksType
- azure-diagnosticsDebug Azure production issues on Azure using AppLens, Azure Monitor, resource health, and safe triage. WHEN: debug production issues, troubleshoot app service, app service high CPU, app service deploySkillsJul 2026
- systematic-debuggingUse when encountering any bug, test failure, or unexpected behavior, before proposing fixesSkillsJul 2026
- safe-debugRigor Debug / Rigor Audit skill for deep learning research work. Use when the user pastes a traceback, terminal error, CUDA OOM, checkpoint load failure, shape mismatch, NaN loss symptom, or training SkillsMay 2026
- explore-runRigor Improve / Rigor Explore run leaf skill for bounded exploratory evidence in deep learning research repositories. Use when the researcher explicitly authorizes exploratory runs such as small-subseSkillsMay 2026
- minimal-run-and-auditRigor Run skill for README-first deep learning repo reproduction. Use when the task is specifically to capture or normalize evidence from the selected smoke test or documented inference or evaluation SkillsMay 2026
- insforge-debugUse when diagnosing problems in an InsForge project — reactive failures (SDK error object, HTTP 4xx/5xx, gateway timeout 502/503/504, edge function failure or timeout, login/OAuth/auth errors, RLS denSkillsJul 2026
