TFmini-i LiDAR Laser Range Sensor (12m) Wiki - DFRobot

Introduction

TFmini-i LiDAR is an industrial-grade medium-range distance sensor. Its maximum detection range can reach up to 12m and it has an adjustable frame rate with a maximum of 1KHz. It has a PC/ABS/PMMA enclosure with IP65 water and dust resistance. It supports a wide range of input voltages (7-30V) with reverse protection to protect the internal circuit. RS485 communication interface, standard Modbus protocol and multiple built-in operating modes are included for the users to change their parameters and configurations to meet different applications. The TFmini-i LiDAR can be used on the Arduino UNO R3 through the TTL to RS485 Shield, and it can also be used on the Raspberry Pi through the USB to RS485 module. Those two ways provided by DFRobot can make TFmini-i LiDAR simpler to be used.

How does TFmini-i LiDAR work?

TFmini-i is a single point LiDAR, which is based on Pulse Time of Flight (PTOF). It adopts an incoherent energy receiving mode, and the detection is mainly based on Pulse counting. TFmini-i emits a narrow pulse laser, which is collimated by the transmitting lens to form a collimated light, which enters the receiving system after being reflected by the measured target and is focused on the APD detector by the receiving lens. The time between the transmitted signal and the received signal is calculated through the circuit amplification and filtering, and the distance between TFmini-i and the measured target can be calculated through the speed of light.

Feature

• Wide range of input voltages (7-30V) with reverse protection
• RS485 interface communication
• Adjustable frame rate with a maximum of 1KHz
• Medium range detection (up to 12m)
• IP65 protection for industrial application
• Compatible with Arduino UNO R3 and Raspberry Pi

Application

• Detection of vehicle and pedestrian
• Vehicle collision avoidance and safety warning systems
• UAV assisted takeoff and landing
• Altimeter

Specification

Board Overview

Size Diagram

Pinout Diagram

NOTE: Do not mix UART cable with RS485 wire, otherwise it will cause damage to LiDAR MCU.

Tutorial

Requirements

• Hardware
  • TFmini-i LiDAR x1
  • DFRduino UNO R3 x1
  • Raspberry Pi x1
  • USB to RS485 Module x1
  • RS485 Shield for Arduino x1

• Software
  • Arduino IDE

On the Arduino

Turn the switch of the expansion board to the OFF first, burn codes into the board, then turn it to the ON. Select the serial port baud rate 115200.

NOTE:Do not mix UART cable with RS485 wire, otherwise it will cause damage to LiDAR MCU.

Connection Diagram

Sample Code

uint8_t Com[8] = {0x01, 0x03, 0x00, 0x00, 0x00, 0x01, 0x84, 0x0a};
void setup()
{
  Serial.begin(115200);    //Initialize the serial ports
}
void loop()
{
  int Distance =readDistance();
  Serial.print("Distance = ");
  Serial.print(Distance);
  Serial.println(" CM");
  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;
}

On the Raspberry Pi

1. Wiring diagram

2. Install wiringpi library

cd /tmp
wget https://project-downloads.drogon.net/wiringpi-latest.deb   //download wiringpi library
sudo dpkg -i wiringpi-latest.deb  //install wiringpi library
cd Desktop/          //enter desktop folder
git clone https://github.com/DFRobotdl/TF02-i.git     //ownload the sample code and save it on the desktop
cd TF02-i/

3. Check USB device

Type in the terminal

sudo ls -l /dev

Find the USB device that has just been connected to the Raspberry Pi (Every time the USB device is connected to the Raspberry Pi, the device port will change, so you need to check the actual port each time you connect the device to the Raspberry Pi).

4.Compile and run the sample code

Use the terminal to open the folder where the program is located, compile and run.

gcc -Wall -lwiringPi -o TF02 TF02.c
sudo ./TF02

Finally, you can see the accurate measured distance value.

FAQ

For any questions, advice or cool ideas to share, please visit the DFRobot Forum.

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