Build Your Own LoRaWAN Sensor With SenseCAP S2110 XIAO LoRaWAN SensorBuilder

This is the source code for SenseCAP S2110 XIAO LoRaWAN SensorBuilder and it provides an open-source tool to build your own LoRaWAN sensors.

Hardware Set Up

• Step 1: Unscrew the four screws on the SensorBuilder lid to open the lid and unscrew the PG connector (with a coin)

• Step 2: If you have already made the connection between the XIAO SensorBuilder and the Data Logger with the 4 wires, it is recommended to remove the red wire which connects to the 5V pin of the XIAO SensorBuilder

• Step 3: Connect one end of a USB Type-C cable to the XIAO SensorBuilder and the other to the PC

Now you can open Arduino IDE on the PC and start tinkering!

Software Set Up

• Step 1: Install the necessary sensor support library :

  Grove_BMP280
  Grove_Sunlight_Sensor
  Seeed_Arduino_MultiGas
  Seeed_Arduino_BME68x
  Seeed_Arduino_UltrasonicRanger
  Seeed_Arduino_MultiGas
  arduino-i2c-scd4x
  ArduinoRS485
  ArduinoModbus

• Step 2: Install Seeed Studio XIAO RP2040 board.

  refer to Seeed Studio XIAO RP2040 with Arduino | Seeed Studio Wiki

• Step 3: Add pin defines.

  Add the following lines at the end of the C:\Users\${UserName}\AppData\Local\Arduino15\packages\rp2040\hardware\rp2040\3.1.0\variants\seeed_xiao_rp2040\pins_arduino.h file.

  // RS485
  #define RS485_SERIAL_PORT Serial1
  #define RS485_DEFAULT_DE_PIN D8
  #define RS485_DEFAULT_RE_PIN D8
  #define RS485_DEFAULT_TX_PIN 1

How to Add a New Sensor

• Step 1: Add a sensorNew.hpp file to the src\sensor folder for the new sensor.

• Step 2: Define the sensor class and implement the init() and sample() functions.

  The sensor class should inherits from the sensorClass class, and implement the init() and sample() functions. The init() function is used to initialize the sensor, and than returns a register offset value for Modbus communication. The sample() function is used to read the sensor data, returns true when the data is valid, and returns false when the data is invalid.

• Step 3: Include the sensorNEW.hpp file and call it.

  Add line #include "sensorNew.hpp" to the src\sensor\sensorBuilder.hpp file. In the setup() function of the sensorBuilder.ino file, create the new sensor class object and call the SensorBuilder.addSensor() function with it as an argument.

Refer to the following code :

void setup()
{
  Serial.begin(9600);
  SensorBuilder.check_grove();

  /* sensor list */
  sensorUltrasonic *ultrasonic = new sensorUltrasonic();
  SensorBuilder.addSensor(ultrasonic);

  // add new sensor to sensor list
  sensorNew *newSensor = new sensorNew();
  SensorBuilder.addSensor(newSensor);

  SensorBuilder.begin();
}

NOTE: the Modbus register address for the new sensor will start from 0x0034, the register bit width for each measurement value is 32, so the register address offset between two adjacent measurement values is 2.

Modbus Register Table

Modbus register addresses 0x0000 to 0x0003 are reserved for storing module system information, where 0x0000 is the modbus address with a default value of 1 and a maximum value of 247, 0x0001 is the serial port baud rate with a default value of 96 (corresponding to 9600), and 0x0002 to 0x0003 are for software version.