/* minimal solution - reading gauge indicator (here a device from Absolute-System)
   @author torsten roehl
   @see this code is based on https://www.instructables.com/id/Interfacing-a-Digital-Micrometer-to-a-Microcontrol/
   (there is a little big in the code from instructables - only ocurs for high inch values! )
*/


/*  ADJUST AREA START  */

/* pin configuration */
int pinREQ = 5;
int pinDATA = 2;
int pinCLK = 3;

/* pooling intervall */
int sleep = 100;
/* baudrate */
int bd = 9600;

/*  ADJUST AREA END  */

/* Keep FIXED! - data protocol format */
byte digits[13];
float value;

void setup() {

  /*    SERIAL_8N1 (the default)  */
  Serial.begin(bd);

  pinMode(pinREQ, OUTPUT);
  pinMode(pinCLK, INPUT_PULLUP);
  pinMode(pinDATA, INPUT_PULLUP);
  digitalWrite(pinREQ, LOW); // set request at high

}

void loop() {

  readDialGauge();
  decodeDialGauge();
  serialInfoMonitor();

  delay(sleep);
}


/*
   Read the dial gauge.
   After a call to this function the array digits[13] contains all data according to the data protocol.
   For normal data reading the first four digits should by all 'F', the function returns false if this is not the case.



*/
boolean readDialGauge() {

  /**
     Generate request by making REQ active (low level)!
  */
  digitalWrite(pinREQ, HIGH); // generate set request

  /* read 13 nibble (52 bit) */
  for (int i = 0; i < 13; i++ ) {
    int digit = 0;
    for (int j = 0; j < 4; j++) {

      while ( digitalRead(pinCLK) == LOW) {}/* Wait for CLOCK=HIGH */
      while ( digitalRead(pinCLK) == HIGH) {} /* Wait for CLOCK=LOW  */

      bitWrite(digit, j /*pos*/, (digitalRead(pinDATA) & 0x1));
    }

    digits[i] = digit;
  }

  digitalWrite(pinREQ, LOW);


  /* d1-d4 should be all oxF */
  int header = digits[0] + digits[1] + digits[2] + digits[3];
  return header == 60 ? true : false;
}


/*
   decodeDialGauge (according to the digomatic-protocol)
   Note: A call to readDialGauge is necessary to use this function!

   i) value - contains the (signed) value read out from the gauge indicator
   ii) units - if units is equal to 0 then mm is used, otherwise (1) inch is in use
   iii) decimal - the number of decimal. mm corresponds to 3 decimal numbers, whereas inch has five decimal numbers.

   return (signed) measured value
*/

void decodeDialGauge() {

  int units = digits[12];    // 0=mm or 1=inch
  int decimal = digits[11];  // 3 for mm and 5 for inch

  value = (float)digits[5] * 10000 + (float)digits[6] * 10000 + (float) digits[7] * 1000 + (float)digits[8] * 100 + (float)digits[9] * 10 + (float) digits[10];
  /* assuming digits[11] is allways 3 */
  value /= 1000.0;

  if (units == 1 )
    value /= 100.0;

  if (digits[4] == 8)
    value *= -1.0;
}

/*
   Helper function: This function decodes and writes the data from the dial gauge to the arduino serial monitor for debugging purposes.
   Note: A call to readDialGauge and decodeGauge is necessary to use this  function!

*/
void serialInfoMonitor() {

  int units = digits[12];// 0=mm or 1=inch
  int decimal = digits[11];// 3 for mm and 5 for inch
 
  String info = " (mm)";
  if (units == 1 )
    info = " (inch)";

  Serial.print(value, decimal );
  Serial.println(info);

}