U8 Series Laser Distance Sensor

Arduino library for U8 series laser distance sensor. U8 series is an accurate LIDAR (ligth detection and ranging) sensor module with +/- 1 mm accuracy from JRT Meter Technology. This library support for U81x and other laser sensor module from JRT using U(S)ART interface.

Installation

Using the Arduino IDE Library Manager

1. Choose Sketch -> Include Library -> Manage Libraries...
2. Type U8xLaser into the search box.
3. Search a row with title U8xLaserDistance.
4. Click the Install button to install the library.

Using Git

Open terminal, Git bash, or command prompt in Arduino library folder then run following command. Default library folder for windows is C:\Users\{username}\Documents\Arduino and for linux is ~/Documents/Arduino/libraries/.

git clone https://github.com/chandrawi/U8x_Laser_Distance.git

Wiring Connection

To work with U8x LIDAR sensor, you must connect Arduino UART pins and PWREN pin to the sensor like picture below.

Initialization

To work with the library, first you must include U8xLaser.h. Then initialize class by creating an object with a HardwareSerial instance and a PWREN pin and optionally a RESET pin.

#define PWREN_PIN PA15
HardwareSerial SerialU8x(PB7, PB6);
U8xLaser U8x(SerialU8x, PWREN_PIN);

Alternatively a default Serial object will be used if a HardwareSerial instance not supplied.

#define PWREN_PIN PA15
U8xLaser U8x(PWREN_PIN);

Read Status

Read current laser module status is done by calling status method.

uint16_t status = U8x.status();

The return value of the method has meaning like described in the table below.

Status Code	Description
U8X_STAT_NO_ERR	No error
U8X_STAT_VLTG_LOW	Power input too low, power voltage shoul >= 2.2 V
U8X_STAT_INT_ERR	Internal error, don't care
U8X_STAT_TEMP_LOW	Module temperature is too low (< -20 °C)
U8X_STAT_TEMP_HIGH	Module temperature is too high (> +40 °C)
U8X_STAT_OUT_RANGE	Target out range
U8X_STAT_INV_RESULT	Invalid measure result
U8X_STAT_BG_LIGHT	Background light too strong
U8X_STAT_LASER_WEAK	Laser signal too weak
U8X_STAT_LASER_STRONG	Laser signal too strong
U8X_STAT_HW_FAULT_1	Hardware fault 1
U8X_STAT_HW_FAULT_2	Hardware fault 2
U8X_STAT_HW_FAULT_3	Hardware fault 3
U8X_STAT_HW_FAULT_4	Hardware fault 4
U8X_STAT_HW_FAULT_5	Hardware fault 5
U8X_STAT_LASER_UNSTABLE	Laser signal not stable
U8X_STAT_HW_FAULT_6	Hardware fault 6
U8X_STAT_HW_FAULT_7	Hardware fault 7
U8X_STAT_INV_FRAME	Invalid frame

Get Hardware and Software Version and S/N

Get information about laser module hardware version, software version and serial number is done by calling corresponding method.

uint16_t hwVer = U8x.hardwareVersion();
uint16_t swVer = U8x.softwareVersion();
uint32_t serNum = U8x.serialNumber();

Laser Control

Laser can be turn on and off using following code.

U8x.laserOn();
U8x.laserOff();

Single Shot Measurement

Single shot measurement is done by calling measureSingle, measureSingleSlow, or measureSingleFast method for auto, slow (accurate), or fast measuring mode respectively. Those methods will block the program and return measurement result.

void loop() {
  int32_t distance;
  // Single shot auto measurement
  distance = U8x.measureSingle();
  // Single shot slow (accurate) measurement
  distance = U8x.measureSingleSlow();
  // Single shot fast measurement
  distance = U8x.measureSingleFast();
}

Continuous Measurement

Continuous measurement is started by calling startMeasure, startMeasureSlow, or startMeasureFast method for auto, slow (accurate), or fast measuring mode respectively. measureResult method must be called to get measurement result after continuous measurement started. For example:

void setup() {
  // Start continuous slow (accurate) measurement
  U8x.startMeasureSlow();
}

void loop() {
  // Get measurement result
  int32_t distance = U8x.measureResult();
}

When no longer needed, continuous mode can be terminated using stopMeasure method. For example, to get average of some measurement see code below.

void loop() {
  // Start continuous slow (accurate) measurement
  U8x.startMeasureFast();
  // Get average of 4 measurement results
  int32_t sum = 0;
  for (int8_t i=0; i<4; i++) {
    sum += U8x.measureResult();
  }
  int32_t distance = (sum + 2) / 4;
  // Stop continuous measurement
  U8x.stopMeasure();
  delay(5000);
}

Signal Quality

After any measurement is done, the laser signal quality of the last measurement can retrieved by calling getSignalQuality method.

uint16_t sigQual = U8x.getSignalQuality();

Low Power Application

This library provide sleep method to put laser module in power down mode and wake method to wake the module. During power down mode, power consumed is very low. You can see low power implementation in this example.

Examples

See examples here