MiniR4VernierLib.cpp

Go to the documentation of this file.

 
/* This is a library to make using Vernier LabQuest sensors and the Digital Control Unit (DCU)
with a Vernier Arduino Interface Shield (BT-ARD) easier. There are several useful functions:
AutoID: reads information about the sensor, including calibration information
readSensor:  returns calibrated sensor data from Analog 1
readMotionDetector: returns the distance reading from a Vernier Motion Detector in Digital 1
DCU:  allows you to control the output of a Vernier Digital Control Unit (DCU) in Digital 2
DCUStep:  allows you to easily control a stepper motor connected to the DCU in Digital 2
DCUPWM: allows you to use PWM from the DCU line 4 in Digital 2
 
Version 1.0.6 fixes an error that occurred from how _sensorName, _shorName, and _sensorUnits were
initialized with a const char value.
*/
 
// #define DEBUG1 // add for print statements
// single channel version
#include "MiniR4VernierLib.h"
#include "Arduino.h"
#include <Wire.h>   // used for I2C communication
 
MiniR4VernierLib::MiniR4VernierLib()
{
    pinMode(2, INPUT);    // Echo pin; this is the pin that goes high when an echo is received
    pinMode(3, OUTPUT);   // Trigger Pin used for Motion Detector
    pinMode(6, OUTPUT);   // set up DCU lines, assuming it is on Digital 2
    pinMode(7, OUTPUT);
    pinMode(8, OUTPUT);
    pinMode(9, OUTPUT);
    pinMode(10, OUTPUT);         // multiplexer on the shield, lsb
    pinMode(11, OUTPUT);         // multiplexer on the shield, msb
    pinMode(12, INPUT_PULLUP);   // button on DCU
    pinMode(13, OUTPUT);         // LED on shield
}
 
void MiniR4VernierLib::autoID()
{
    _channel         = 1;   //this is the Analog 1 only version of the library\  
  _sensorNumber=0;
    _voltageID       = 0;
    _slope           = 1;
    _intercept       = 0;
    _cFactor         = 0;
    _page            = 0;   // calibration storage page (always 0 for resistor ID sensors)
    _calEquationType = 1;   // for all resisto-ID sensrs, but thermistors and some I2C sensors; it
                            // will be changed in that case below
    const int _device = 0x50;   // used for I2C autoID
    byte      _floatbyte[5];
    byte      _sensorData[128];
    for (_i = 0; _i < 128; _i++)   // clear our digital ID sensor data
    {
        _sensorData[_i] = 0;
    }
 
    byte _resistorIDInfo[][32] = {
        {78,  97,  109, 101, 32, 48,  32,  32, 32, 32,  32,  32,  32,  32, 83, 104,
         111, 114, 116, 78,  97, 109, 101, 32, 85, 110, 105, 116, 115, 32, 32, 0},   
        {84,  72, 101, 114, 109, 111, 99, 111, 117, 112, 108, 101, 32, 32, 84, 101, 109,
         112, 32, 32,  32,  32,  32,  32, 68,  101, 103, 32,  67,  32, 32, 0},   // Thermocouple*
        {86, 111, 108, 116, 97, 103, 101, 32, 43, 47, 45, 49, 48, 86, 86, 32,
         32, 32,  32,  32,  32, 32,  32,  32, 86, 32, 32, 32, 32, 32, 32, 0},   // voltage +/-10*
        {67, 117, 114, 114, 101, 110, 116, 32, 32, 32, 32, 32, 32, 32, 73, 32,
         32, 32,  32,  32,  32,  32,  32,  32, 65, 32, 32, 32, 32, 32, 32, 0},   // Current*
        {82,  101, 115, 105, 115, 116, 97, 110, 99, 101, 32,  32,  32, 32, 82, 101,
         115, 32,  32,  32,  32,  32,  32, 32,  79, 104, 109, 115, 32, 32, 32, 0},   // resistance*
        {69,  76,  32, 84, 101, 109, 112, 32, 32, 32,  32,  32, 32, 32, 84, 101,
         109, 112, 32, 32, 32,  32,  32,  32, 68, 101, 103, 32, 67, 32, 32, 0},   // 5 EL Temp*
        {109, 105, 115, 115, 105, 110, 103, 32, 32,  32,  32,  32,  32,  32,  109, 105,
         115, 115, 105, 110, 103, 32,  32,  32, 109, 105, 115, 115, 105, 110, 103, 0},   // missing*
        {109, 105, 115, 115, 105, 110, 103, 32, 32,  32,  32,  32,  32,  32,  109, 105,
         115, 115, 105, 110, 103, 32,  32,  32, 109, 105, 115, 115, 105, 110, 103, 0},   // missing*
        {68,  105, 102, 102, 32, 86, 111, 108, 116, 97, 103, 101, 32, 32, 80, 111,
         116, 32,  32,  32,  32, 32, 32,  32,  86,  32, 32,  32,  32, 32, 32, 0},   // Diff voltage*
        {67, 117, 114, 114, 101, 110, 116, 32, 32, 32, 32, 32, 32, 32, 73, 32,
         32, 32,  32,  32,  32,  32,  32,  32, 65, 32, 32, 32, 32, 32, 32, 0},   // Current*
        {84,  101, 109, 112, 101, 114, 97, 116, 117, 114, 101, 32, 32, 32, 84, 101,
         109, 112, 32,  32,  32,  32,  32, 32,  68,  101, 103, 32, 67, 32, 32, 0},   // 10 Temp*
        {86,  111, 108, 116, 97, 103, 101, 32, 43, 47, 45, 51, 48, 86, 80, 111,
         116, 32,  32,  32,  32, 32,  32,  32, 86, 32, 32, 32, 32, 32, 32, 0},   // voltage +/-30*
        {84,  73,  32,  76, 105, 103, 104, 116, 32, 32, 32, 32, 32, 32, 76, 105,
         103, 104, 116, 32, 32,  32,  32,  32,  32, 32, 32, 32, 32, 32, 32, 0},   // TI Light*
        {69, 120, 32, 72, 101, 97, 114, 116, 32, 82, 97, 116, 101, 32, 86, 32,
         32, 32,  32, 32, 32,  32, 32,  32,  86, 32, 32, 32,  32,  32, 32, 0},   // Ex Heart Rate*
        {82, 97, 119, 32, 86, 111, 108, 116, 115, 32, 32, 32, 32, 32, 86, 32,
         32, 32, 32,  32, 32, 32,  32,  32,  86,  32, 32, 32, 32, 32, 32, 0},   // Raw Volts*
        {69, 75, 71, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 69, 75,
         71, 32, 32, 32, 32, 32, 2,  86, 32, 32, 32, 32, 32, 32, 0},   // 15 EKG*
        {109, 105, 115, 115, 105, 110, 103, 32, 32,  32,  32,  32,  32,  32,  109, 105,
         115, 115, 105, 110, 103, 32,  32,  32, 109, 105, 115, 115, 105, 110, 103, 0},   // missing*
        {67, 97, 114, 98, 111, 110, 32, 68, 105, 111, 120, 105, 100, 101, 67, 79,
         50, 32, 32,  32, 32,  32,  32, 32, 112, 112, 109, 32,  32,  32,  32, 0},   // CO2*
        {79, 120, 121, 103, 101, 110, 32, 32, 32, 32, 32, 32, 32, 32, 79, 50,
         32, 32,  32,  32,  32,  32,  32, 32, 37, 32, 32, 32, 32, 32, 32, 0}   // O2*};
    };
 
    _sensorName[16] = '\0';   // I am using 16 characters here, plus terminator.
    _shortName[12]  = '\0';   // 12 characters on name, plus terminator.
    _sensorUnits[7] = '\0';   // 7 characters units, plus terminator.
    _sensorName[17] = '\0';   // THESE MAY NOT BE NECESSARY
    _shortName[13]  = '\0';
    _sensorUnits[8] = '\0';
    // set multiplexer to match channel: NOTE THIS IS GETTING READY FOR A 2-CHANNEL VERSION
    if (_channel == 1) {
        digitalWrite(10, LOW);   // set multiplexer for BTA1
    } else {
        digitalWrite(10, HIGH);   // set multiplexer for BTA2
    }
    digitalWrite(11, LOW);   //
 
#if defined DEBUG1
    Serial.print("_resistorIDInfo array: ");   // only if "#define" is in the code
    for (_i = 0; _i < 33; _i++)                // display whole line of array as numbers
    {
        Serial.print(_resistorIDInfo[_sensorNumber][_i]);
        Serial.print(",");
    }
    Serial.println("}");
    Serial.println("_resistorIDInfo array as char: ");   // only if "#define" is in the code
    for (_i = 0; _i < 33; _i++)   // display whole line of array as characters
    {
        Serial.print(char(_resistorIDInfo[_sensorNumber][_i]));
    }
    Serial.println("}");
#endif   // DEBUG1
 
    // Read BTA1 Sensor with resistor ID:
    _voltageID = analogRead(A5) / 1024.0 * 5.00;   // convert from count to voltage could use Vcc!!!
    if (_voltageID > 0.86 & _voltageID < 0.95) _sensorNumber = 1;   // Thermocouple
    if (_voltageID > 3.72 & _voltageID < 3.86) _sensorNumber = 2;   // voltage +/-10 V
    if (_voltageID > 1.92 & _voltageID < 2.13) _sensorNumber = 3;   // TI Current Probe (not used)
    if (_voltageID > 1.18 & _voltageID < 1.30) _sensorNumber = 4;   // resistance
    if (_voltageID > 3.27 & _voltageID < 3.68) _sensorNumber = 5;   // Extra-Long Temperature Probe
    if (_voltageID > 4.64 & _voltageID < 4.73) _sensorNumber = 8;   // Differential voltage
    if (_voltageID > 4.73 & _voltageID < 4.82) _sensorNumber = 9;   // Current
    if (_voltageID > 2.38 & _voltageID < 2.63)
        _sensorNumber = 10;   // Stainless Steel or Surface Temperature Probe
    if (_voltageID > 2.85 & _voltageID < 3.15) _sensorNumber = 11;   // voltage 30 V
    if (_voltageID > 1.52 & _voltageID < 1.68) _sensorNumber = 12;   // TILT, TI Light Sensor
    if (_voltageID > 0.43 & _voltageID < 0.48) _sensorNumber = 13;   // Exercise Heart Rate
    if (_voltageID > 4.08 & _voltageID < 4.16) _sensorNumber = 14;   // Raw voltage
    if (_voltageID > 0.62 & _voltageID < 0.68) _sensorNumber = 15;   // EKG
    if (_voltageID > 4.32 & _voltageID < 4.40) _sensorNumber = 17;   // CO2
    if (_voltageID > 4.50 & _voltageID < 4.59) _sensorNumber = 18;   // Oxygen
 
    if (_sensorNumber != 0)   // if any resistor ID sensor found
    {
        // code below assumes the _resistorIDInfo array is correct and sticks those numbers, for a
        // particular sensor into the sensorData array. read Name char string into array in the righ
        for (_i = 0; _i < 14; _i++)   //
        {
            _sensorData[9 + _i] = _resistorIDInfo[_sensorNumber][_i];
        }
        // read ShortName char string into array in the right spots, characters 15-24
        for (_i = 0; _i < 10; _i++)   //
        {
            _sensorData[29 + _i] = _resistorIDInfo[_sensorNumber][14 + _i];
        }
        // read Units char string into array in the right spots, characters 25-32
        for (_i = 0; _i < 7; _i++)   //
        {
            _sensorData[83 + _i] =
                _resistorIDInfo[_sensorNumber][24 + _i];   // note page is always 0
        }
 
        switch (_sensorNumber) {
        case 1:
            // Thermocouple ;
            _slope     = -2.45455;
            _intercept = 6.2115;
            break;
        case 2:
            // voltage +/- 10V" ;
            _slope = 4;   // note correction for Sparkfun circuit done in calculation of voltage!
            _intercept = -10;
            break;
        case 3:
            // Current;
            _slope     = -2.665;
            _intercept = 6.325;
            break;
        case 4:
            // resistance ;
            _slope     = -2.5;
            _intercept = 6.25;
            break;
        case 5:
            // EL Temp   //Extra-Long Temperature Probe
            _slope     = 58.341;
            _intercept = -53.073;
            break;
        case 8:
            // Diff voltage ;
            _slope     = -2.5;
            _intercept = 6.25;
            break;
        case 9:
            // Current ;
            _slope     = -0.25;
            _intercept = 0.625;
            break;
        case 10:
            // Temperature ;
            _slope           = 1;
            _intercept       = 0;
            _calEquationType = 12;   // Steinhart-Hart (for this sensor only)
            break;
        case 11:
            // voltage +/- 30V" ;//
            _slope     = 15.41;
            _intercept = -40.35;
            break;
        case 12:
            // TI Light ;
            _slope     = 1;
            _intercept = 0;
            break;
        case 13:
            // Exercise Heart Rate ;
            _slope     = 1;
            _intercept = 0;
            break;
        case 14:
            // Raw voltage ;
            _slope     = 1;
            _intercept = 0;
            break;
        case 15:
            // EKG ;
            _slope     = 1;
            _intercept = 0;
            break;
        case 17:
            // Carbon Dioxide ;
            _slope     = 1;
            _intercept = 0;
            break;
        case 18:
            // Oxygen ;
            _slope     = 1;
            _intercept = 0;
            break;
        default:
            _slope     = 1;
            _intercept = 0;
            break;
        }   // end of switch case
    }   // end of if a resistor ID sensor is found
 
 
 
    if (_sensorNumber == 0)   // no resistor ID sensor found; check I2C
    {
        pinMode(A4, OUTPUT);   // Turn on the I2C communication!!! this can cause problems!!!
        pinMode(A5, OUTPUT);
 
        // check for digital ID sensor:
        Wire.begin();   // join i2c bus (address optional for master)
        // Reading _device first time... ;
        Wire.beginTransmission(_device);   // Now we're going to read it back
        Wire.write(0x0);                   // Sending address 0, so it knows where we'll want
        Wire.endTransmission();
        int _x =
            Wire.requestFrom(_device, 32);   // Start new transmission and keep reading for 32 bytes
        // note: the default buffer size for Arduino is 23 bytes. You can change it to larger. It
        // would be desirable to change it to 128 bytes and read all the data in one read. That is
        // the way all Vernier
        // interfaces do it. is done as follows:  add#define SERIAL_BUFFER_SIZE 128
        // check it in your sketch with:
        // Serial.print(SERIAL_BUFFER_SIZE);
        _i = 1;
        while (_x > 1) {
            _x              = Wire.available();
            byte _c         = Wire.read();   // Read a byte and write it out to the Serial port
            _sensorData[_i] = _c;
            _i++;
        }
        // Reading device second time... ;
        Wire.beginTransmission(_device);   // Now we're going to read it back
        Wire.write(0x20);                  // Sending address 0, so it knows where we'll want
        Wire.endTransmission();            // to read from
        _x = Wire.requestFrom(
            _device, 32);   // Start new transmission and keep reading for 128 bytes
        _i = 1;
        while (_x > 1) {
            _x                   = Wire.available();
            byte _c              = Wire.read();   // Read a byte and write it out to the Serial port
            _sensorData[_i + 32] = _c;
            _i++;
        }
        // Reading device third time... ;
        Wire.beginTransmission(_device);   // Now we're going to read it back
        Wire.write(0x40);                  // Sending address 0, so it knows where we'll want
        Wire.endTransmission();            // to read from
        _x = Wire.requestFrom(
            _device, 32);   // Start new transmission and keep reading for 128 bytes
        _i = 1;
        while (_x > 1) {
            _x                   = Wire.available();
            byte _c              = Wire.read();   // Read a byte and write it out to the Serial port
            _sensorData[_i + 64] = _c;
            _i++;
        }
        // Reading device a forth time... ;
        Wire.beginTransmission(_device);   // Now we're going to read it back
        Wire.write(0x60);                  // Sending address 0, so it knows where we'll want
        Wire.endTransmission();            // to read from
        _x = Wire.requestFrom(
            _device, 32);   // Start new transmission and keep reading for 128 bytes
        _i = 1;
        while (_x > 1) {
            _x                   = Wire.available();
            byte _c              = Wire.read();   // Read a byte and write it out to the Serial port
            _sensorData[_i + 96] = _c;
            _i++;
        }
        _voltageID = -1;   
        ;                  // Determines the  sensorNumber:
        _sensorNumber = _sensorData[2];
 
        // Determine the calibration equation type:
        _calEquationType = _sensorData[57];
 
        // Determines the  calibration page:
        _page = _sensorData[70];
        // the code below uses the calibration page set:
        // Intercept starts at 71 for page 1, 90 for p2, and 109 for p3
 
        // Determines intercept:
        for (_i = 0; _i < 4; _i++) {
            _floatbyte[_i] = _sensorData[_i + 71 + (_page) * 19];
        }
        float _j   = *(float*)&_floatbyte;
        _intercept = _j;
 
        // Determines slope:
        //  slope starts at 75 for page 1, 94 for p2, and 113 for p3
        for (_i = 0; _i < 4; _i++) {
            _floatbyte[_i] = _sensorData[_i + 75 + (_page * 19)];
        }
        float _y = *(float*)&_floatbyte;
        _slope   = _y;
 
        pinMode(A4, INPUT);   // Turn off the I2C communication!!! this can cause problems!!!
        pinMode(A5, INPUT);
 
    }   // end of if I2C autoID
 
 
    // Determine the sensor name:
    for (_i = 0; _i < 16; _i++) {
        char _c         = _sensorData[_i + 9];
        _sensorName[_i] = _c;
    }
    _sensorName[16] = '\0';
 
    // Determine the short name:
    for (_i = 0; _i < 11; _i++) {
        char _c        = _sensorData[_i + 29];   // changed from 28 to 29
        _shortName[_i] = _c;
    }
    _shortName[11] = '\0';
 
    // determine the Units:
    //  units start at 83 for page 1, 102 for p2, and 121 for p3
    for (_i = 0; _i < 7; _i++) {
        char _c          = _sensorData[_i + 83 + (_page) * 19];
        _sensorUnits[_i] = _c;
    }
    _sensorUnits[7] = '\0';   // add terminating character
    // Special handling for ISEs, CA, NH4, NO3, or Cl
    if (_sensorNumber > 37 && _sensorNumber < 42) strncpy(_sensorUnits, "mV     ", 7);
    // Special calibration for Potasium ISE:
    if (_sensorNumber == 113)
        strncpy(_sensorUnits, "mV      ", 7);   // assign name based on sensor number
 
#if defined DEBUG1
    Serial.print("_voltageID ");   // use this line, if you want to check the autoID voltage
    Serial.println(_voltageID);    // use this line, if you want to check the autoID voltage/*
 
    Serial.print("sensorData array: ");   // only if "#define" is in the code
    for (_i = 0; _i < 129; _i++)          // display whole array
    {
        Serial.print(_i);
        Serial.print(" ");
        Serial.print(_sensorData[_i]);
        Serial.print(" ");
        Serial.println(char(_sensorData[_i]));
    }
#endif   // DEBUG1
}   // end of AutoID function
 
float MiniR4VernierLib::readSensor()   // This function converts count to sensor reading
{
    int   _numberAveraged = 10;   // number of readings averaged for reading reported
    int   _count;
    int   _sum = 0;
    float _voltage;
    byte  _buttonState = 0;   // condition of button
    // better code for reading voltage:
    if (_sensorNumber == 2 ||
        _sensorNumber == 11)   // one of two sensors using the +/- 10 volt line
    {
        for (_i = 0; _i < _numberAveraged; _i++) {
            if (_channel == 1) {
                _count = analogRead(A1);   // read 0 to 5 volt analog lines, Analog 1
            } else {
                _count = analogRead(A3);   // read 0 to 5 volt analog lines Analog 2
            }
            _sum = _sum + _count;
        }   // end of for loop
    }   // end of if
    else {
        for (_i = 0; _i < _numberAveraged; _i++) {
            if (_channel == 1) {
                _count = analogRead(A0);   // read 0 to 5 volt analog lines, Analog 1
            } else {
                _count = analogRead(A2);   // read 0 to 5 volt analog lines Analog 2
            }
            _sum = _sum + _count;
        }   // end of for loop
    }   // end of else
    _voltage = _sum / _numberAveraged / 1024.0 *
               5.0;   // convert average count to voltage (0 to 5 volt input)
    _sensorReading = _intercept + _voltage * _slope;   // for all linear sensors
 
    // the code below deals with BTA sensors which have non-linear calibrations
    // Special calibration for Wide Range Tempeature Sensor(78):
    if (_sensorNumber == 78)
        _sensorReading = _intercept + _voltage * _slope + _cFactor * _voltage * _voltage;
    // Special quadratic calibration for Ethanol Sensor(97):
    if (_sensorNumber == 97) _sensorReading = _intercept * pow(_voltage, _slope);
    // Special quadratic calibration for Sound Level Sensor(118)
    if (_sensorNumber == 118)
        _sensorReading = _intercept + _slope * _voltage + _cFactor * _voltage * _voltage;
    // Special calibration for Melt Station(92):
    if (_sensorNumber == 92)
        _sensorReading = _intercept + _voltage * _slope + _cFactor * _voltage * _voltage;
    // Special calibration for ISEs, CA(38), NH4(39), NO3(40), Cl(41):
    if (_sensorNumber > 37 && _sensorNumber < 42) _sensorReading = (137.55 * _voltage - 168.2);
    // Special calibration for Potasium(113) ISE:
    if (_sensorNumber == 113) _sensorReading = (137.55 * _voltage - 168.2);   // Potasium ISE
    if (_sensorNumber == 123)
        _sensorReading = _intercept + _voltage * _slope + _cFactor * _voltage * _voltage;
    // Special quadratic calibration for New (Oct. 2016 Thermocouple(123));
    if (_sensorNumber == 10)   // if thermistor:
    {
        /* Inputs ADC count from Thermistor and outputs Temperature in Celsius
           note that this requires: include <math.h>
          There is a huge amount of information on the web about using thermistors with the Arduino.
          Here we are concerned about using the Vernier Stainless Steel Temperature Probe TMP-BTA
          and the Vernier Surface Temperature Probe STS-BTA, but the general principles are easy to
          extend to other thermistors. This version utilizes the Steinhart-Hart Thermistor Equation:
             Temperature in Kelvin = 1 / {A + B[ln(R)] + C[ln(R)]3}
            for the themistor in the Vernier TMP-BTA probe:
             A =0.00102119 , B = 0.000222468 and C = 1.33342E-7
             Using these values should get agreement within 1 degree C to the same probe used with
          one of the Vernier interfaces
 
          Schematic:
            [Ground] -- [thermistor] -------- | -- [15,000 ohm bridge resistor] --[Vcc (5v)]
                                              |
                                         Analog Pin 0
 
          For the circuit above:
 
          resistance = ( count*RawADC /(1024-count))
        */
        float _logR;
        float _resistor;
        float logR;                 
        _resistor        = 15000;   // 15k resistor in series with thermistor
        long _resistance = (_resistor * _voltage) / (5.0 - _voltage);
        _logR =
            log(_resistance);   // Saving the Log(resistance) so not to calculate  it 4 times later
        _sensorReading =
            1 / (0.00102119 + (0.000222468 * _logR + (0.000000133342 * _logR * _logR * _logR)));
        _sensorReading = _sensorReading - 273.15;   // Convert Kelvin to Celsius
    }   // end of thermistor code
 
    _buttonState = digitalRead(12);   // button on shield
    // check if the pushbutton is pressed.
    // if it is, the buttonState is HIGH:
    if (_buttonState == LOW)   // button down
    {
        digitalWrite(13, LOW);   // turn on LED on shield
        Serial.print("V= ");
        Serial.println(_voltage, 1);   // display raw voltage on Serial Monitor
 
    } else
        return _sensorReading;
 
}   // END OF Read Sensor
 
 
void MiniR4VernierLib::DCUPWM(int PWMSetting)
{
 
    digitalWrite(6, LOW);
    digitalWrite(7, LOW);
    digitalWrite(8, LOW);
    if (PWMSetting < 0) PWMSetting = 0;
    if (PWMSetting > 255) PWMSetting = 255;
    // Serial.print("PWM output set to ");
    // Serial.println(PWMSetting);
    analogWrite(9, PWMSetting);   // range 0 to 255
}
 
void MiniR4VernierLib::DCUStep(int stepCount, int stepDirection, int stepDelay)
{
    int DCUStepPattern[4];   // pattern used to drive step motor
    if (stepDirection == 0) {
 
        /*   The following sequences are for a "normal" step motor.
          5,9,10,6 steps the motor CW
          Reverse the order for CCW
          */
        DCUStepPattern[0] = 5;   // CW
        DCUStepPattern[1] = 9;
        DCUStepPattern[2] = 10;
        DCUStepPattern[3] = 6;
    } else {
        DCUStepPattern[0] = 6;   // CCW
        DCUStepPattern[1] = 10;
        DCUStepPattern[2] = 9;
        DCUStepPattern[3] = 5;
    }
    DCU(0);   // Turn off all lines
    delay(100);
    Serial.print("step motor rotate for ");
    Serial.print(stepCount);
    Serial.print(" steps, in direction ");
    Serial.print(stepDirection);
    Serial.print(", with delay of ");
    Serial.print(stepDelay);
    Serial.println(" ms");
    for (int _x = 0; _x <= stepCount; _x++)   // set up step pattern
    {
        int _output =
            _x % 4;   // % = modulo: returns the remainder of x divided by the value (4) in the case
        // as "_x" increments "_output" will progress from 0, 1, 2, 3 repeating
        int _stepValue = DCUStepPattern[_output];
        DCU(_stepValue);   // This points to the case for the DCU. See void DCU below.
        delay(stepDelay);
    };   // end of for
}   // end of PWM
 
void MiniR4VernierLib::DCU(int DCUSetting)
{
 
    switch (DCUSetting) {
    case 0:
        digitalWrite(6, LOW);
        digitalWrite(7, LOW);
        digitalWrite(8, LOW);
        digitalWrite(9, LOW);
        break;
    case 1:
        digitalWrite(6, HIGH);
        digitalWrite(7, LOW);
        digitalWrite(8, LOW);
        digitalWrite(9, LOW);
        break;
    case 2:
        digitalWrite(6, LOW);
        digitalWrite(7, HIGH);
        digitalWrite(8, LOW);
        digitalWrite(9, LOW);
        break;
    case 3:
        digitalWrite(6, HIGH);
        digitalWrite(7, HIGH);
        digitalWrite(8, LOW);
        digitalWrite(9, LOW);
        break;
    case 4:
        digitalWrite(6, LOW);
        digitalWrite(7, LOW);
        digitalWrite(8, HIGH);
        digitalWrite(9, LOW);
        break;
    case 5:
        digitalWrite(6, HIGH);
        digitalWrite(7, LOW);
        digitalWrite(8, HIGH);
        digitalWrite(9, LOW);
        break;
    case 6:
        digitalWrite(6, LOW);
        digitalWrite(7, HIGH);
        digitalWrite(8, HIGH);
        digitalWrite(9, LOW);
        break;
    case 7:
        digitalWrite(6, HIGH);
        digitalWrite(7, HIGH);
        digitalWrite(8, HIGH);
        digitalWrite(9, LOW);
        break;
    case 8:
        digitalWrite(6, LOW);
        digitalWrite(7, LOW);
        digitalWrite(8, LOW);
        digitalWrite(9, HIGH);
        break;
    case 9:
        digitalWrite(6, HIGH);
        digitalWrite(7, LOW);
        digitalWrite(8, LOW);
        digitalWrite(9, HIGH);
        break;
    case 10:
        digitalWrite(6, LOW);
        digitalWrite(7, HIGH);
        digitalWrite(8, LOW);
        digitalWrite(9, HIGH);
        break;
    case 11:
        digitalWrite(6, HIGH);
        digitalWrite(7, HIGH);
        digitalWrite(8, LOW);
        digitalWrite(9, HIGH);
        break;
    case 12:
        digitalWrite(6, LOW);
        digitalWrite(7, LOW);
        digitalWrite(8, HIGH);
        digitalWrite(9, HIGH);
        break;
    case 13:
        digitalWrite(6, HIGH);
        digitalWrite(7, LOW);
        digitalWrite(8, HIGH);
        digitalWrite(9, HIGH);
        break;
    case 14:
        digitalWrite(6, LOW);
        digitalWrite(7, HIGH);
        digitalWrite(8, HIGH);
        digitalWrite(9, HIGH);
        break;
    case 15:
        digitalWrite(6, HIGH);
        digitalWrite(7, HIGH);
        digitalWrite(8, HIGH);
        digitalWrite(9, HIGH);
        break;
    }
}   // end of DCU
 
float MiniR4VernierLib::readMotionDetector()   // This function reads Motion Detector
{
    /*
VernierMotionDetector
Takes data from a Vernier Motion Detector connected to the Digital 1 connector.
 
This sketch measures the time taken for the ultrasound to return (in microseconds)
and then calculates the corresponding distance (based on the speed of ultrasound
in air) and displays the distance (in cm) on the Serial Monitor.
 
Here is how the Vernier Motion Detector works:
- when pin 2 on BTD is pulled high, this triggers the ultrasound pulse
- the program then starts timing but then delays 0.9 ms *(blanking time,
   0.9 seconds is the time it takes ultrasound to travel 15 cm twice (round trip))
- the program then monitors pin 1 on the BTD, waiting for it to go high.
This happens when an echo is detected.
 
See www.vernier.com/arduino for more information.
 */
 
    long _time;       // clock reading in microseconds
    long _duration;   // time it take echo to return
    int  _val = 0;
    digitalWrite(3, LOW);
    delayMicroseconds(4000);
    digitalWrite(3, HIGH);    // start the ultrasound pulse using Trigger Pin 3
    _time = micros();         // note time
    delayMicroseconds(900);   // delay during the blanking time
    do {
        _val = digitalRead(2);   // read echo pin 2
                                 // if no echo, repeat loop and wait:
    } while (_val == LOW);
    _duration = micros() - _time;
    /* The speed of sound is 340 m/s.
    The ultrasound travels out and back, so to find the distance of the
    object we take half of the distance traveled.*/
    _distance = _duration * 340 / 2 /
                10000;   // note the 340 is the speed of sound in m/s. note convert to cm
    return _distance;
}