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Weather Buoy - ESP32 4G/LTE Solar

  • On-water solar powered autonomous wind and weather station
  • ESP32, SIM7600E, GILL MaxiMet GMX501

weather buoy on water

electronics mounted on buoy with sun shield


rendering electronics


test setup

Electronics part list

Part Description Links Cost (ex. delivery)
Waterproof housing Fibox PCM200/100T, 255x180x100 Polycarbonat Fibox 6016927, conrad EUR 46
Weather station Gill MaxiMet: ultrasonic windspeed/direction, compass, solar radiation GILL MaxiMet GMX501 Note: GMX200 costs half, just lacks solar EUR 1500-3000
Microcontroller Lilygo ESP32 LILYGO® TTGO T-PCIE ESP32-WROVER-B EUR 10
4G/LTE Modem SimCom 7600 PCIE-SIM7600E Module EUR 30
Solar panel 12V, 20W, monocrystalline, water proof IP65 Offgridtec EUR 27
Solar charging controller 12V LiFePo4 capable, 5V power for microcontroller Victron Bluesolar, MPPT, 75/10 EUR 80
RS232 to TTL converter MAX3232 to convert weatherstation's RS232 to 3.3V serial Sparkfun MAX3232 tranceiver breakout EUR 5
Voltage/Current sensor MAX471 module, uses ESP32 ADC as there is no serial available to connect the ESP32 to the Victron Solar charger MAX471 module with voltage divider, MAX471 datasheet ~EUR 2
Water Temperature sensor DS18B20 cable DS18B20 cable ~EUR 3
On-Board Temperature sensor DS18B20 TSO module DS18B20 TSO ~EUR 1
Battery LiFePo4, 12V, 6Ah, 4S1P, including BMS Jubatec EUR 60
5V Power convert ~14V Battery voltage to 5V for ESP32 TracoPower TSR 1-2450 DC/DC-Wandler, 24V/DC 5V/DC 1A 6W EUR 6
M12 male front-mount Solar panel power, 4-pins, 2 pins combined to double current of 4A per pin 7000-13501-9710050 EUR 10
M12 female with cable Solar panel power, 4-pins, 2 pins combined to double current of 4A per pin, soldered to solar panel 7000-12221-6340200 EUR 10
M8 male connector soldered to Water temperature sensor cable 7000-08401-0000000 EUR 11
M8 female front-mount 3-pin Water temperature sensor 7000-08571-9700050 EUR 9
M12 female front-mount 5-pin RS232 data and 5V power connection to Maximet weatherstation 7000-13561-9720100 EUR 12
M12 male connector cable 5-pin RS232 data and 5V power connection to Maximet weatherstation with Maximet specific IP67 soldered Connector 7000-12041-6250300 EUR 11
Pressure compensation unit Wiska EVPS - Pressure compensation unit, VentPLUG, plastic, metric WISKA EVPS 40 10106593 EUR 4


wiring diagrams

CAD: 3D-print & PCB

files are in the folder /cad

System: Fusion 360 live model PCB: Fusion 360 live model

how to order a PCB:


  • built with ESP-IDF Version 4.3 or later
  • adds software components for
    • Cellular handling for SimCom 7600E Modem
    • Max417 current/voltage measurement
    • Comfortable/safer Strings
    • reading/parsing Gill Maximet data from serial interface
  • new as of February 2022:
    • remotely configuring Gill Maximet wind/weather stations
    • NMEA2000 data output for a real-time Display e.g. Garmin GNX130
    • SMS and Buzzer alerting based on GPS geofence, tilt sensor, and Maximet unplugging
    • Use exactly same electronics also to simulate a maximet station for testing purposes
    • upgraded to ESP-IDF 4.4
    • improved serial/UART handling to maximet and modem for performance and robustness

Lilygo TTGP T-PCIE SIM7600E PIN usage

  • UART0: RX: GPIO3, TX: GPIO1 (USB, logging, debugging)
  • UART1: RX: GPI13, TX: GPIO14 (Maximet RS232)
  • UART2: RX: GPIO16, TX: GPIO17 (SimCom Modem)
  • ADC: GPIO39 (Max471, Voltage)
  • ADC: GPIO34 (Max471, Current)
  • TWAI: RX: GPIO22, TX: GPIO21 (I2C ports for driving NMEA2000 display)
  • OUT: GPIO19 (Buzzer, up to max 70mA)

SIM7600E modem firmware


cannot flash via serial/USB anymore

observing weird crashes, especially after changing git branches


ESP32 GSM/LTE operated solar-powered autonomous weather station for buoys on the water with a GILL Maximet weather station.








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