LilyGO T-Echo Weather & GPS Logger

A standalone Arduino-based firmware for the LilyGO T-Echo (nRF52840) that transforms it into a portable weather station and GPS logger utilizing the onboard E-Paper display.

Features

• Weather Station Page: Displays live Temperature, Humidity, Pressure, and Altitude using the onboard BME280 sensor.
• GPS Navigation Page: Displays Latitude, Longitude, Altitude, Speed, UTC Time, and Satellite count using the onboard L76K GNSS module.
• E-Paper UI: A clean, low-power user interface running on the 1.54" SPI E-Paper display, automatically updating every 30 seconds.
• Battery Status: Displays accurate battery percentage based on the onboard ADC voltage divider.
• Capacitive Touch: Use the capacitive touch button on the side to toggle between the Weather and GPS pages.
• Heartbeat LED: Blinks the green LED every 2 seconds to indicate system health.

Hardware Requirements

• LilyGO T-Echo (or T-Echo Plus)
• Includes: nRF52840 MCU, BME280 Sensor, L76K GNSS, 1.54" E-Paper display.

Software Dependencies

This project is built using PlatformIO.

Libraries Used:

• adafruit/Adafruit BME280 Library
• adafruit/Adafruit Unified Sensor
• mikalhart/TinyGPSPlus
• adafruit/Adafruit GFX Library
• GxEPD (from LilyGO official repository)

Installation & Flashing

Using PlatformIO (Recommended)

1. Clone this repository.
2. Open the folder in VSCode with the PlatformIO extension installed.
3. The platformio.ini is already configured for the correct board (nrf52840_dk_adafruit) which ensures all 48 pins of the nRF52840 map correctly 1:1.
4. Build the project.
5. Flash via UF2 Bootloader:
   • Double-click the reset button on the T-Echo.
   • The device will mount as a USB flash drive named TECHOBOOT.
   • Convert your .hex to .uf2 using uf2conv.py.
   • Copy the firmware.uf2 file to the TECHOBOOT drive. The device will automatically reboot and start the logger.

Pin Configurations (T-Echo Reference)

This project uses the exact hardware mappings defined in the official LilyGO specifications.

• E-Paper Display: CS (30), DC (28), RST (2), BUSY (3), MOSI (29), MISO (38), SCK (31), Power (43)
• BME280 (I2C): SDA (26), SCL (27), Address: 0x77
• GPS L76K (UART2): RX (41), TX (40), Wakeup (34), Reset (37), PPS (36)
• Touch Button: Pin 11 (Active HIGH)
• LEDs: Green (33), Red (35), Blue (14)

Acknowledgements

• Based on the official LilyGO T-Echo examples.
• Uses the robust GxEPD library for display driving.