read neje laser temp via arduino

#include <Arduino.h>
#include <SoftwareSerial.h>

#define LASER_INPUT_PIN 2 //aka D2
#define TEMPERATURE_OUTPUT_PIN 5 //aka D5 PWM
#define TEMPERATURE_BYTE_INDEX 4 // see https://i.imgur.com/AcpoeKa.png

#define DEBUG //print temp value on serial con

SoftwareSerial softSerial(LASER_INPUT_PIN, 3); // RX, TX

byte laser_packet[7];
byte index = 0U;

void setup() {
#ifdef DEBUG
    Serial.begin(9600);
#endif
    softSerial.begin(200);
    pinMode(TEMPERATURE_OUTPUT_PIN, OUTPUT);
}

void loop() {
   //analogWrite(TEMPERATURE_OUTPUT_PIN, 170);
    while (softSerial.available() > 0) {
        byte b = softSerial.read();
        if (b == 0xFF) { //start of packet
            index = 0U;
        }
        laser_packet[index++] = b; //store byte
    }
    if (index == 7) {
#ifdef DEBUG
        Serial.print("Temp: ");
        uint16_t temp = laser_packet[TEMPERATURE_BYTE_INDEX];
        Serial.print(temp);
        Serial.println("C");
#endif

    }
}