How to read bytearray from arduino pin in arduino sketch

Question

I'm using the DYP-ME007TX sensor with arduino uno. The output from this sensor comes in packets of 4-bytes:

Data[0]= 0xFF: Packet Header
Data[1]= 0x0-0xFF: Data Most Significant Byte (MSB)
Data[2]= 0x0-0xFF: Data Least Significant Byte (LSB)
Data[3]= 0x0-0xFF: Data Checksum: = (0XFF + MSB + LSB) & 0xFF

Data is in MILLIMETERS

16 bit value in mm = Data[1] << 8 | Data[2]

How can exctract this packet in arduino sketch and extract millimeter number?

Answer 1

I found the answer from forum.arduino.cc There is a sketch

#include <SoftwareSerial.h>

// TX_PIN is not used by the sensor, since that the it only transmits!
#define PING_RX_PIN 6
#define PING_TX_PIN 7

SoftwareSerial mySerial(PING_RX_PIN, PING_TX_PIN);

long inches = 0, mili = 0;
byte mybuffer[4] = {0};
byte bitpos = 0;

void setup() {
  Serial.begin(9600);

  mySerial.begin(9600);
}


void loop() {
  bitpos = 0;
  while (mySerial.available()) {
    // the first byte is ALWAYS 0xFF and I'm not using the checksum (last byte)
    // if your print the mySerial.read() data as HEX until it is not available, you will get several measures for the distance (FF-XX-XX-XX-FF-YY-YY-YY-FF-...). I think that is some kind of internal buffer, so I'm only considering the first 4 bytes in the sequence (which I hope that are the most recent! :D )
    if (bitpos < 4) {
      mybuffer[bitpos++] = mySerial.read();
    } else break;
  }
  mySerial.flush(); // discard older values in the next read

  mili = mybuffer[1]<<8 | mybuffer[2]; // 0x-- : 0xb3b2 : 0xb1b0 : 0x--
  Serial.print("PING: ");
  Serial.print(mili/10);
  Serial.println("sm");
  delay(500);
}