4G GNSS-RTK Example Code for Arduino

The article provides example code for using Arduino with I2C communication to achieve high precision positioning using a GNSS-RTK kit. It covers hardware and software preparation, including installation of necessary libraries and setup instructions. The article also includes a wiring diagram for connecting the Arduino UNO R3 to the GNSS-RTK kit and demonstrates how to apply for a CORS account to facilitate precise data retrieval. Sample code is provided to guide users through reading RTK data in 4G mode. Finally, it references the NMEA 0183 Protocol Standard for advanced data analysis.

Hardware preparation

DFR0216-2 DFRduino UNO R3 × 1
4G GNSS-RTK High Precision Positioning Kit x1

Software preparation

Arduino IDE Download Arduino IDE
Download and install the RTK Library
How to install libraries?

I2C Wiring Diagram

UNO R3	PIN	GNSS-RTK	PIN
UNO R3	VCC	GNSS-RTK	VCC(RED)
UNO R3	GND	GNSS-RTK	GND(BLACK)
UNO R3	SCL	GNSS-RTK	SCL(BLUE)
UNO R3	SDA	GNSS-RTK	SDA(GREEN)

Other Preparation Work

Apply for a CORS account from a domestic service provider (e.g., China's Continuously Operating Reference Station network).
Replace the placeholders in the code with your CORS account details:
- USER_NAME: CORS account username
- USER_PASSWORD: CORS account password
- SERVER_ADDR: CORS server IP address
- MOUNT_POINT: CORS service mount point
- port: CORS server port number

Sample Code

 /*!
  * @file  getAllGnss4G.ino
  * @brief read all rtk data at 4G mode
  * @copyright Copyright (c) 2010 DFRobot Co.Ltd (http://www.dfrobot.com)
  * @license The MIT License (MIT)
  * @author ZhixinLiu([email protected])
  * @version V0.5.0
  * @date 2024-10-28
  * @url https://github.com/DFRobot/DFRobot_RTK_4G
  */

#include "DFRobot_RTK_4G.h"

void callback(char *data, uint8_t len)
{
  for(uint8_t i = 0; i < len; i++){
    Serial.print((char)data[i]);
  }
}

#define I2C_COMMUNICATION  //use I2C for communication, but use the serial port for communication if the line of codes were masked

#ifdef  I2C_COMMUNICATION
  DFRobot_RTK_4G_I2C rtk(&Wire ,DEVICE_ADDR);
#else
/* -----------------------------------------------------------------------------------------------------
 * |  Sensor  | Connect line | Leonardo/Mega2560/M0 |    UNO    | ESP8266 | ESP32 |  microbit  |   m0  |
 * |   VCC    |=============>|        VCC           |    VCC    |   VCC   |  VCC  |     X      |  vcc  |
 * |   GND    |=============>|        GND           |    GND    |   GND   |  GND  |     X      |  gnd  |
 * |   RX     |=============>|     Serial1 TX1      |     5     |   5/D6  |  D2   |     X      |  tx1  |
 * |   TX     |=============>|     Serial1 RX1      |     4     |   4/D7  |  D3   |     X      |  rx1  |
 * ----------------------------------------------------------------------------------------------------*/
/* Baud rate cannot be changed  */
  #if defined(ARDUINO_AVR_UNO) || defined(ESP8266)
    SoftwareSerial mySerial(4, 5);
    DFRobot_RTK_4G_UART rtk(&mySerial, 57600);
  #elif defined(ESP32)
    DFRobot_RTK_4G_UART rtk(&Serial1, 115200 ,/*rx*/D2 ,/*tx*/D3);
  #else
    DFRobot_RTK_4G_UART rtk(&Serial1, 115200);
  #endif
#endif


#define  USER_NAME      "maplays7874"
#define  USER_PASSWORD  "79546"
#define  SERVER_ADDR    "103.45.160.41"
#define  MOUNT_POINT    "RTCM33GRCEJpro"
uint16_t port = 8002;
String   result = "";

void setup()
{
  Serial.begin(115200);
  while(!rtk.begin()){
    Serial.println("NO Deivces !");
    delay(1000);
  }
  Serial.println("Device connected !");

  rtk.setModule(eMoudle4g);
  while(rtk.getModule() != eMoudle4g){
    Serial.println("Module type is not 4G!  please wait!");
    delay(1000);
  }
  rtk.setUserName(USER_NAME, strlen(USER_NAME));
  rtk.setUserPassword(USER_PASSWORD, strlen(USER_PASSWORD));
  rtk.setServerAddr(SERVER_ADDR, strlen(SERVER_ADDR));
  rtk.setMountPoint(MOUNT_POINT, strlen(MOUNT_POINT));
  rtk.setPort(port);
  Serial.println("please wait 4g module init!");
  Serial.println("connecting network please wait !");
  result = rtk.connect();
  if((String)"CONNECT SUCCESSFUL" == result){
    Serial.println("connect success");
  }else{
    Serial.println(result);
  }

  rtk.setCallback(callback);
}

void loop()
{
  // Please note that there is no judgment of timeout reconnection for the 4G module here
  rtk.getAllGnss();
  if(!rtk.getConnectState()){
    Serial.println("restart connect .....");
    rtk.reConnect();
  }
}

Result

For more advanced data analysis, please refer to the Standard Messages section (2.2) of the NMEA 0183 Protocol Standard.

Example Code for Arduino(I2C)-High Precision Positioning