Ultrasonic Ranging Sensor(3m) Arduino WiKi - DFRobot

Introduction

This is an ultrasonic obstacle avoidance sensor designed for robot automation control applications. It addresses the issues commonly found in the current market such as large blind zones, wide measurement angles, long response times, and poor installation adaptability for ultrasonic sensors. With a measurement range of up to 3m, it offers advantages such as small blind zones, narrow measurement angles, short response times, filtering of same-frequency interference, compact size, high installation adaptability, dust and waterproof capabilities, long lifespan, and high reliability.

Utilizing innovative ultrasound processing technology, it can identify and filter out foreign ultrasound, resulting in more stable and reliable data output. This greatly reduces the probability of same-frequency interference, meeting the complex environmental application requirements in the field of robot automation control.

It features RS4585 output for sensor data, and users can use it in conjunction with Arduino's TTL to RS485 expansion board (DFR0259). It finds wide applications in robot obstacle avoidance, automatic control, parking management systems, security gate detection, access control systems, and object proximity and presence detection.

Features

• Compact in size, with a small blind zone
• Lightweight and fast response time
• Waterproof level of IP67
• Intelligent ultrasound processing technology for reduced interference

Specification

• Measurement range: 2-300cm
• Measurement accuracy: 1 + (S * 0.3%) cm
• Operating voltage: 3.3-12V
• Operating current: ≤10mA
• Communication method: RS485
• Output response time: 15-750ms
• Power-on delay operating time: ≤1000ms
• Detection angle: 30-60°
• Operating temperature: -25°C~ 65°C
• Operating humidity: 65% ~ 80%RH
• Storage temperature: -30°C ~ 80°C
• Storage humidity: 65% ~ 90%RH

Board Overview

Dimensional Drawing

Installation opening suggestion

Modbus protocol description

1、Default communication parameters

2、Modbus protocol parameters

3、Modbus protocol format

The user machine is the master device and the sensor is the slave device.

Host send (read):

Slave response (read):

Host send (write):

Slave response (write):

4、Modbus register

Register data is high byte before and low byte after.

• Modbus register table 1

• Modbus register table 2

• Influence of Baud Rate on Single Packet Communication Duration

Note: The higher the baud rate, the shorter the single packet communication time.

5、Examples of Modbus communication

Example 1: Reading Processing Value Data

Host: 01 03 01 00 00 01 85 F6

Slave: 01 03 02 02 F2 38 A1

Explain: The address of the sensor is 0x01, and the processing distance value is 0x02F2, which is converted into decimal 754 mm..

Example 2: Reading Real-time Value Data

Host: 01 03 01 01 00 01 D4 36

Slave: 01 03 02 02 EF F8 A8

Explain: The address of the sensor is 0x01, and the real-time distance value is 0x02EF, which is converted into decimal 751mm.

Example 3: Reading Temperature Value Data

Host: 01 03 01 02 00 01 24 36

Slave: 01 03 02 01 2C B8 09

Explain: The sensor address is 0x01, the real-time temperature value is 0x012C, and it is 30.0℃ when converted into decimal.

Example 4: Modify the slave address

Host: 01 06 02 00 05 48 71

Slave: 01 06 02 00 05 48 71

Explain: The sensor address was changed from 0x01 to 0x05.

Example 5: Reading Baud Rate

Host: 01 03 02 01 00 01 D4 72

Slave: 01 03 02 00 03 F8 45

Explain: Read the baud rate, which is 9600bps.

Example 6: Setting Baud Rate

Host: 01 06 02 01 00 03 99 B3

Slave: 01 06 02 01 00 03 99 B3

Explain: Set the baud rate to 9600bps.

Tutorial

Requirements

• Hardware
  • DFRduino UNO R3 (or similar) x 1
  • RS485 Shield for Arduino x1
  • Ultrasonic Ranging Sensor(3m) x1

• Software
  • Arduino IDE

Connection Diagram

Before burning the code, please switch the transceiver mode switch of the expansion board to AUTO, and the run/compile switch to OFF; after burning the code, switch the run/compile switch to ON, and select the serial port baud rate of 115200.

Sample Code

uint8_t Com[8] = {0x01,0x03,0x01,0x01,0x00,0x01,0xd4,0x36};
void setup()
{
  Serial.begin(115200);    
}
void loop()
{
  int Distance =readDistance();
  Serial.print("Distance = ");
  Serial.print(Distance);
  Serial.println(" mm");
  delay(500);
}

int readDistance(void)
{
  uint8_t Data[10] = {0};
  uint8_t ch = 0;
  bool flag = 1;
  int Distance = 0;
  while (flag) {
    delay(100);
    Serial.write(Com, 8);
    delay(10);
    if (readN(&ch, 1) == 1) {
      if (ch == 0x01) {
        Data[0] = ch;
        if (readN(&ch, 1) == 1) {
          if (ch == 0x03) {
            Data[1] = ch;
            if (readN(&ch, 1) == 1) {
              if (ch == 0x02) {
                Data[2] = ch;
                if (readN(&Data[3], 4) == 4) {
                  if (CRC16_2(Data, 5) == (Data[5] * 256 + Data[6])) {
                    Distance = Data[3] * 256 + Data[4];
                    //Serial.println(Distance);
                    flag = 0;
                  }
                }
              }
            }
          }
        }
      }
    }
    Serial.flush();

  }
  return Distance;
}

uint8_t readN(uint8_t *buf, size_t len)
{
  size_t offset = 0, left = len;
  int16_t Tineout = 500;
  uint8_t  *buffer = buf;
  long curr = millis();
  while (left) {
    if (Serial.available()) {
      buffer[offset] = Serial.read();
      offset++;
      left--;
    }
    if (millis() - curr > Tineout) {
      break;
    }
  }
  return offset;
}

unsigned int CRC16_2(unsigned char *buf, int len)
{
  unsigned int crc = 0xFFFF;
  for (int pos = 0; pos < len; pos++)
  {
    crc ^= (unsigned int)buf[pos];
    for (int i = 8; i != 0; i--)
    {
      if ((crc & 0x0001) != 0)
      {
        crc >>= 1;
        crc ^= 0xA001;
      }
      else
      {
        crc >>= 1;
      }
    }
  }

  crc = ((crc & 0x00ff) << 8) | ((crc & 0xff00) >> 8);
  return crc;
}

Expected Results

View the distance value detected by the sensor through the serial port.

FAQ

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