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Phase 7 — Field UI

Take the antenna outdoors: after a cold start, FIX climbs NONE → 3D, the status bar goes green, and lat/lon lock on the 240×240. No new wires.

As built — TFT showing FIX 3D, green bar, SAT 8/10 HDOP 2.3, lat/lon locked

As built — a clear-sky 3D fix drives the panel green, sats and HDOP climbing, lat/lon locked. ST7789 on the breadboard; ESP32 + ATGM336H off-frame in the jumpers.

Firmware

firmware/07-field-ui/ · src/main.cpp

Same UART2 RX=16 TX=17 @ 9600, same TFT SPI + init(240, 240, SPI_MODE3). Tracker: Firmware.

Preconditions

  • Checkpoint 6 passed (panel draws)
  • Antenna on; outdoor or clear sky for a real 3D fix

7.1 Demo

  1. Flash (see 7.2). Screen shows FIX NONE (red bar) while the receiver acquires.
  2. Indoors: sats may tick up slowly; UTC can update before lat/lon; zeros for position are normal.
  3. Move outdoors — antenna flat to open sky, away from eaves.
  4. Sats used climb → bar yellow (2D / poor HDOP) → green FIX 3D; LAT/LON fill; HDOP drops.
  5. Walk ~20 m — position drifts; SPD ticks when moving.

Serial: fix=… sats=…/… hdop=… lat=… lon=… about once a second (mirrors the glass).

flowchart LR
  GNSS[ATGM336H NMEA] --> Parse[GGA / RMC / GSV]
  Parse --> Fix[FIX / SAT / HDOP]
  Parse --> Pos[LAT / LON / SPD / UTC]
  Fix --> TFT[ST7789]
  Pos --> TFT
  Parse -->|115200| USB[ttyUSB0]
On screen From
Status bar colour Fix + HDOP — red NONE · yellow 2D / HDOP>2.5 · green 3D
FIX GGA quality (0 → NONE; else treated as 3D here)
SAT GGA sats used / GSV in view
HDOP GGA HDOP
LAT / LON GGA (or RMC when status A)
SPD RMC speed (knots)
UTC GGA / RMC time

A learning demo, not a survey instrument

Consumer GNSS without corrections is metre-class at best. The panel is a field readout of the NMEA pipeline — not a cadastral tool.

7.2 Flash

Stop any serial monitor on the port first. Check which /dev/ttyUSB* is up.

ls /dev/ttyUSB*
cd firmware/07-field-ui
pio run -e esp32dev -t upload --upload-port /dev/ttyUSB0

/dev/ttyUSB0
Processing esp32dev (platform: espressif32; board: esp32dev; framework: arduino)
--------------------------------------------------------------------------------
Verbose mode can be enabled via `-v, --verbose` option
CONFIGURATION: https://docs.platformio.org/page/boards/espressif32/esp32dev.html
PLATFORM: Espressif 32 (55.3.39) > Espressif ESP32 Dev Module
HARDWARE: ESP32 240MHz, 320KB RAM, 4MB Flash
DEBUG: Current (cmsis-dap) External (cmsis-dap, esp-bridge, esp-prog, esp-prog-2, iot-bus-jtag, jlink, minimodule, olimex-arm-usb-ocd, olimex-arm-usb-ocd-h, olimex-arm-usb-tiny-h, olimex-jtag-tiny, tumpa)
PACKAGES: 
 - contrib-piohome @ 3.4.4 
 - framework-arduinoespressif32 @ 3.3.9 
 - framework-arduinoespressif32-libs @ 5.5.4+sha.735507283d 
 - tool-esptoolpy @ 5.3.0 
 - tool-xtensa-esp-elf-gdb @ 17.1.0+20260402 
 - toolchain-xtensa-esp-elf @ 14.2.0+20260121
LDF: Library Dependency Finder -> https://bit.ly/configure-pio-ldf
LDF Modes: Finder ~ chain, Compatibility ~ soft
Found 48 compatible libraries
Scanning dependencies...
Dependency Graph
|-- Adafruit ST7735 and ST7789 Library @ 1.12.0
|-- Adafruit GFX Library @ 1.13.0
|-- Adafruit BusIO @ 1.17.4
|-- SPI @ 3.3.9
Building in release mode
esptool v5.3.0
Retrieving maximum program size .pio/build/esp32dev/firmware.elf
Checking size .pio/build/esp32dev/firmware.elf
Advanced Memory Usage is available via "PlatformIO Home > Project Inspect"
RAM:   [=         ]   7.3% (used 23988 bytes from 327680 bytes)
Flash: [===       ]  26.8% (used 351016 bytes from 1310720 bytes)
esptool v5.3.0
Configuring upload protocol...
AVAILABLE: cmsis-dap, esp-bridge, esp-prog, esp-prog-2, espota, esptool, iot-bus-jtag, jlink, minimodule, olimex-arm-usb-ocd, olimex-arm-usb-ocd-h, olimex-arm-usb-tiny-h, olimex-jtag-tiny, tumpa
CURRENT: upload_protocol = esptool
Looking for upload port...
Uploading .pio/build/esp32dev/firmware.bin
esptool v5.3.0
Serial port /dev/ttyUSB0:
Connecting.....
Connected to ESP32 on /dev/ttyUSB0:
Chip type:          ESP32-D0WD-V3 (revision v3.1)
Features:           Wi-Fi, BT, Dual Core + LP Core, 240MHz, Vref calibration in eFuse, Coding Scheme None
Crystal frequency:  40MHz
MAC:                8c:94:df:6d:c9:5c

Uploading stub flasher...
Running stub flasher...
Stub flasher running.
Changing baud rate to 460800...
Changed.

Configuring flash size...
Auto-detected flash size: 4MB

Writing '/home/johna/workspace/jajera/esp32-gnss-field/firmware/07-field-ui/.pio/build/esp32dev/bootloader.bin' at 0x00001000...
SHA digest in image updated.
Flash will be erased from 0x00001000 to 0x00006fff...
Compressed 23552 bytes to 15127...

Writing at 0x00001000 [░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░]   0.0% 0/15127 bytes... 

Writing at 0x00006c00 [██████████████████████████████] 100.0% 15127/15127 bytes... 
Wrote 23552 bytes (15127 compressed) at 0x00001000 in 0.8 seconds (245.5 kbit/s).
Verifying written data...
Hash of data verified.

Writing '/home/johna/workspace/jajera/esp32-gnss-field/firmware/07-field-ui/.pio/build/esp32dev/partitions.bin' at 0x00008000...
Flash will be erased from 0x00008000 to 0x00008fff...
Compressed 3072 bytes to 146...

Writing at 0x00008000 [░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░]   0.0% 0/146 bytes... 

Writing at 0x00008c00 [██████████████████████████████] 100.0% 146/146 bytes... 
Wrote 3072 bytes (146 compressed) at 0x00008000 in 0.1 seconds (371.1 kbit/s).
Verifying written data...
Hash of data verified.

Writing '/home/johna/.platformio/packages/framework-arduinoespressif32/tools/partitions/boot_app0.bin' at 0x0000e000...
Flash will be erased from 0x0000e000 to 0x0000ffff...
Compressed 8192 bytes to 47...

Writing at 0x0000e000 [░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░]   0.0% 0/47 bytes... 

Writing at 0x00010000 [██████████████████████████████] 100.0% 47/47 bytes... 
Wrote 8192 bytes (47 compressed) at 0x0000e000 in 0.1 seconds (461.3 kbit/s).
Verifying written data...
Hash of data verified.

Writing '.pio/build/esp32dev/firmware.bin' at 0x00010000...
Flash will be erased from 0x00010000 to 0x00065fff...
Compressed 351424 bytes to 193724...
Writing at 0x00010000 [░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░]   0.0% 0/193724 bytes... 
...
Writing at 0x00065cc0 [██████████████████████████████] 100.0% 193724/193724 bytes... 
Wrote 351424 bytes (193724 compressed) at 0x00010000 in 5.1 seconds (555.9 kbit/s).
Verifying written data...
Hash of data verified.

Hard resetting via RTS pin...
========================= [SUCCESS] Took 19.31 seconds =========================

pio device monitor -b 115200 --port /dev/ttyUSB0

--- Terminal on /dev/ttyUSB0 | 115200 8-N-1
--- Available filters and text transformations: debug, default, direct, esp32_exception_decoder, hexlify, log2file, nocontrol, printable, send_on_enter, time
--- More details at https://bit.ly/pio-monitor-filters
--- Quit: Ctrl+C | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H
gnss-field field-ui — phase 7
fix=NONE sats=0/0 hdop=99.9 lat=0.000000 lon=0.000000
fix=NONE sats=0/0 hdop=25.5 lat=0.000000 lon=0.000000
fix=NONE sats=0/1 hdop=25.5 lat=0.000000 lon=0.000000
fix=NONE sats=0/1 hdop=25.5 lat=0.000000 lon=0.000000

Indoors cold start looks like that — NONE, lat/lon zero, HDOP stuck high. Outdoors the same lines climb to fix=3D with real coordinates (glass capture above).

7.3 Customize

Edit constants in main.cpp, rebuild/flash.

Want… Change
Blank / flaky panel Keep SPI_MODE3; try tft.setSPISpeed(10000000)
Yellow bar sooner / later hdop > 2.5f in statusColor()
Faster / slower UI refresh 1000 ms gate in loop()
Different UART baud GNSS_BAUD (try 115200 if NMEA is garbage)

Checkpoint 7

  • [x] Indoors: serial fix= lines ~1 Hz; TFT shows FIX / SAT / HDOP / LAT / LON
  • [x] Outdoors: FIX 3D, green bar, sats in use, lat/lon locked
  • [x] Knobs documented

v1 bring-up complete. Later phases (SoftAP, SD, PPS, NTRIP) get new folders — don’t rewrite 07-field-ui.