Example Code for Arduino-UART Self-Transmit and Receive

Hardware Preparation

• DFR0216-2 DFRduino UNO R3 with IO Expansion Shield and USB Cable A-B x 1
• DFR627 IIC to dual UART Module x1

Software Preparation

• Download Arduino IDE: Click to download Arduino IDE
• Download the DFRobot_IICSerial1 library: DFRobot_IICSerial library
• About how to install the library?

Wiring Diagram

Other Preparation Work

• Connect pinT of UART1 to its pinR, UART2 TX to its RX.
• Before running the program, check if all the DIP switchs of the module is turned to "1". If it is not, swtich them to 1, or revise the values passed into the formal parameter IA1 and IA0 of the constrctor in the demo below.

Sample Code

/*!
 * @file dataTxAndRx.ino
 * @brief Receive and transmit data via UART. Read the data sent by TX pin via pin RX.
 * @n Experiment phenomenon: connect the TX to RX in Sub UART1 and UART2. Read the data sent by Sub UART and print it out.
 *
 * @copyright   Copyright (c) 2010 DFRobot Co.Ltd (https://www.dfrobot.com)
 * @licence     The MIT License (MIT)
 * @author [Arya]([email protected])
 * @version  V1.0
 * @date  2019-07-28
 * @get from https://www.dfrobot.com
 * @url https://github.com/DFRobot/DFRobot_IICSerial
 */
#include <DFRobot_IICSerial.h>
/*DFRobot_IICSerial Constructor 
 *Parameter&wire  Wire
 *Parameter subUartChannel sub UART channel, for selecting to operate UART1 or UART2
 *@n Available parameter:
     SUBUART_CHANNEL_1  SUBUART_CHANNEL_2
           UART1             UART2
 *Parameter IA1 corresponds with IA1 Level(0 or 1) of DIP switch on the module, and is used for configuring 
 * @n the IIC address of the 6th bit value(default: 1).
 *Parameter IA0 corresponds with IA0 Level(0 or 1) of DIP switch on the module, and is used for configuring
 * @n IIC address of the 5th bit value(default: 1).
 * IIC address configuration: 
 * 7   6   5   4   3   2   1   0
 * 0  IA1 IA0  1   0  C1  C0  0/1
 *@n IIC address only has 7 bits, while there are 8 bits for one byte, so the extra one bit will be filled as 0. 
 *@n The 6th bit corresponds with IA1 Level of DIP switch, can be configured manually.
 *@n The 5th bit corresponds with IA0 Level of DIP switch, can be configured manually. 
 *@n The 4th and 3rd bits are fixed, value 1 and 0 respectively
 *@n The values of the 2nd and 1st bits are the sub UART channels, 00 for sub UART 1, 01 for sub UART 2. 
 *@n The 0 bit represents the operation object: 0 for register, 1 for FIFO cache.
 */
DFRobot_IICSerial iicSerial1(Wire, /*subUartChannel =*/SUBUART_CHANNEL_1,/*IA1 = */1,/*IA0 = */1);//Construct UART1
//DFRobot_IICSerial iicSerial1;//Default constructor, UART1, IA1 = 1, IA0 = 1
DFRobot_IICSerial iicSerial2(Wire, /*subUartChannel =*/SUBUART_CHANNEL_2, /*IA1 = */1,/*IA0 = */1);//Construct UART2

uint8_t flag = 0;//A flag bit, judge whether to print the prompt information of UART1 and UART2.
//if it is 0, print "UART1 receive data: " or "UART2 receive data: "
void setup() {
  Serial.begin(115200);
  /*begin Init function, set band rate according to the selected crystal frequency.
  begin(long unsigned baud) Call the function, set sub UART band rate.
  default setting->Band rate: baud, data format：IIC_SERIAL_8N1, 8 bits data, no check mode, 1 bit stop bit.
  begin(long unsigned baud, uint8_t format)Use the function to set band rate and data format:
  Parameter supported baud:2400, 4800, 57600, 7200, 9600, 14400, 19200, 28800, 38400, 
                76800, 115200, 153600, 230400, 460800, 307200, 921600
  Parameter available format: 
  IIC_SERIAL_8N1  IIC_SERIAL_8N2  IIC_SERIAL_8Z1  IIC_SERIAL_8Z2  IIC_SERIAL_8O1
  IIC_SERIAL_8O2  IIC_SERIAL_8E1  IIC_SERIAL_8E2  IIC_SERIAL_8F1  IIC_SERIAL_8F2
  8 represents the number of data bit, N for no parity, Z for 0 parity, O for Odd parity, E for Even parity,
  F for 1 parity, 1 or 2 for the number of stop bit. Default IIC_SERIAL_8N1
  */
  iicSerial1.begin(/*baud = */115200);/*UART1 init*/
  //iicSerial1.begin(/*baud = */115200, /*format = */IIC_SERIAL_8N1);

  iicSerial2.begin(/*baud = */115200);/*UART2 init*/
  Serial.println("\n+--------------------------------------------+");
  Serial.println("|  Connected UART1's TX pin to RX pin.       |");//Connect pin TX and RX of UART1 
  Serial.println("|  Connected UART2's TX pin to RX pin.       |");//Connect pin TX and RX of UART2
  Serial.println("|  UART1 send a String: \"hello, Serial1!\"    |");//UART1 transmit a string "hello, Serial1!"
  Serial.println("|  UART2 send a number: 123                  |");//UART2 transmit numbers 123
  Serial.println("+--------------------------------------------+");
  iicSerial1.println("hello, Serial1!");//UART1 transmit string:"hello, Serial1!"
  iicSerial2.write(123);//UART2 transmit:123
  Serial.println("Serial to print UART1 and UART2's receive data.");//print the data received by UART1 and UART2
}

void loop() {
  char c;
  if(iicSerial1.available()){/*available return the number of byte in UART1 receive buffer, none- return 0*/
    flag = 0;
    while(iicSerial1.available()){
      if(flag == 0){
        Serial.print("\nUART1 receive data: ");
        flag = 1;
      }
      c = iicSerial1.read();/*Read data of UART1 receive buffer */
      Serial.print(c);
    }
  }
  if(iicSerial2.available()){
    flag = 0;
    while(iicSerial2.available()){
      if(flag == 0){
        Serial.print("\nUART2 receive data: ");
        flag = 1;
      }
      Serial.print(iicSerial2.read());/*Read and print the data of Sub UART2 receive buffer*/
    }
  }
  delay(1000);
}

Result

Serial print the following information.

Additional Information

• The code uses the DFRobot_IICSerial library to initialize UART1 and UART2 with a baud rate of 115200.
• UART1 transmits the string "hello, Serial1!" and UART2 transmits the number 123.
• The serial monitor prints the data received by UART1 and UART2.