LilyGO T-SIM7670G S3

SensMonitor integration

LilyGO T-SIM7670G-S3

Connect an ESP32-S3, SIM7670G LTE Cat-1 modem and optional BME280 sensor to the SensMonitor platform using the open-source smonitor-iot firmware.

Start installation Device registration
  • ESP32-S3Wi-Fi, Bluetooth LE, 16 MB flash
  • SIM7670GLTE Cat-1 and GNSS
  • BME280Temperature, humidity and pressure
LilyGO T-SIM7670G-S3 development board
Photo: LILYGO T-SIM7670G-S3

01 / Overview

A compact LTE Cat-1 monitoring node

The LilyGO T-SIM7670G-S3 combines an ESP32-S3 microcontroller with a SIM7670G LTE Cat-1 modem. It is a practical choice for monitoring stations where standard LTE coverage is available and a simpler Cat-1 cellular connection is preferred over LTE-M or NB-IoT.

01

Controller

ESP32-S3 based board with Wi-Fi, Bluetooth LE, flash and PSRAM support.

02

Cellular network

SIM7670G provides LTE Cat-1 connectivity for data transmission through mobile networks.

03

GNSS location

The SensMonitor modem component can read SIM7670 GNSS location before starting the PPP data session.

04

Sensor telemetry

The default profile can use a BME280 sensor connected over the board I2C interface.

What does the firmware do? On startup, it derives a unique serial number from the ESP32-S3 eFuse MAC address, initializes board power, starts the SIM7670 modem, reads GNSS location when available, establishes PPP data connectivity, synchronizes time, downloads device configuration and sends measurements to SensMonitor.

02 / Preparation

What you need

✓

LilyGO T-SIM7670G-S3 board

✓

Nano SIM card with an active LTE data plan and correct APN

✓

LTE antenna connected before powering the modem

✓

GNSS antenna if location is required

✓

BME280 I2C module and a suitable QWIIC/STEMMA QT cable or wiring

✓

USB-C data cable connected to the ESP32-S3 USB port

✓

Linux, macOS or Windows computer with Git

✓

ESP-IDF 5.x development environment

Before powering the board Insert the SIM card while the board is powered off, connect the LTE antenna, verify APN settings and confirm LTE Cat-1/data service availability with your mobile operator.

03 / Hardware

Connect the BME280

The default SensMonitor profile for this board uses GPIO 3 for SDA, GPIO 2 for SCL and I2C address 0x76. On the Standard variant these lines are intended for the board QWIIC connector. If your module uses 0x77, change the address later in configuration.

BME280LilyGOFunction
VIN / VCC3.3VPower
GNDGNDGround
SDAGPIO 3I2C data
SCLGPIO 2I2C clock
LilyGO T-SIM7670G-S3 board
The board photo is provided for reference. Use the wiring table and your board revision markings when connecting sensors.
Modem and board pins used by the firmware
TX GPIO 4RX GPIO 5PWRKEY GPIO 46DTR GPIO 7PSM GPIO 42QWIIC SDA GPIO 3QWIIC SCL GPIO 2

These modem control connections are routed on the board and do not need to be wired manually. The external sensor bus depends on the connector or header pins available on your board variant.

04 / Firmware

Install and configure smonitor-iot

The project targets ESP-IDF 5.x. Internet access is required during the first build so ESP-IDF Component Manager can download SensMonitor components.

  1. 1

    Install ESP-IDF 5.x

    Follow the official Espressif instructions, then open a terminal with the ESP-IDF environment activated.

    ESP-IDF installation guide ↗

  2. 2

    Download the firmware

    git clone https://github.com/sensmonitor/smonitor-iot.git
cd smonitor-iot
idf.py set-target esp32s3
  3. 3

    Configure the board profile

    cp examples/lilygo_sim7670_s3/sdkconfig.defaults sdkconfig.defaults.local
idf.py menuconfig

    Open the SensMonitor IoT menu and configure APN, PPP authentication and optional sensor settings.

  4. 4

    Check the sensor configuration

    In SensMonitor IoT → I2C sensor, keep BME280, SDA 3, SCL 2 and address 0x76 unless your wiring or board variant is different.

  5. 5

    Build and flash

    idf.py build
idf.py -p /dev/ttyACM0 flash monitor

    Replace /dev/ttyACM0 with your board serial port, such as /dev/ttyUSB0 on Linux or COM5 on Windows.

05 / SensMonitor

Register the device

The firmware automatically derives a serial number from the factory ESP32-S3 MAC address. The serial number identifies the device and is not a secret.

smonitor_iot: Device serial:
SM-ESP32-A1B2C3D4E5F6

DEVICE_NOT_REGISTERED:
Register SM-ESP32-A1B2C3D4E5F6
in the SensMonitor application.
  1. 1

    Sign in at app.sensmonitor.com.

  2. 2

    Open the Devices section and add a new device.

  3. 3

    Select LilyGO T-SIM7670G-S3 as the device type.

  4. 4

    Enter the serial number exactly as shown in the monitor.

  5. 5

    Create a station, assign the device and configure BME280 sensors if used.

  6. 6

    Restart the board so the firmware can request configuration again.

06 / Verification

What a successful connection looks like

Initializing esp_modem for SIM7670
BME280 initialized successfully
SIM7670 GNSS location: latitude=...
Network registration: registered
Modem connected to PPP server
Received device-sample-ack

Ready to measure?

Monitor field data in real time.

Open SensMonitor Firmware on GitHub

Technical sources: SensMonitor firmware, LILYGO product page and LilyGo Modem Series.

Photos belong to their original owner and should be served from the official LILYGO CDN or your uploaded media copy.

LilyGO T-SIM7670G S3