CDI tester project

Hi, I have progressed to a new set of testing where it needs a simple form of a sine wave. A DAC will suffice but I need simple control from the Arduino to do this such as D1=1 D2=0 => zero volt,
D1=1 D2=1 => +12volt, D1=0 D2=0 => -12volt. So I need to use 2 output pins rather than 1. The width of the output should stay the same.

// last change 7/22/18
// 8/17 added code for pulse out width
// 7/14/2017 added correct math and setting for position of pickup
// 10 10/28/2016 adds charging pulse with Timer 2
// lowest RPM = 615 with charge pulse to keep OCR2A <= 255
// CDI Tester Pulse Generator Serial Output Arduino Code


int pot1 = A3; // select the input pin for the pot for rpm
int pot2 = A4; // select the input pin for the pot for pickup location in degrees
int pot3 = A5; // select the input pin for the pot for width of bar on flywheel in degrees
int potValue = 0; // variable to store the value coming from the sensor
int pickupValue = 0; // position of pickup in degrees
int potWidth = 0; // variable to set width of bar on flywheel
int timerTopValue = 12500; // changed from timerTopValue = 0
int outputPin = 4; // select the pin for the output for trigger pulse, changed from 8
int chargePin = 7; // select the pin for the output for charge pulses

volatile boolean trigger = false;
volatile unsigned long delayPeriod;
unsigned long copy_delayPeriod;
volatile unsigned long delayPeriodStart;
float delayDegrees; // changed from int to float for decimal place display
int RPM;
int pickup;
int barWidth;
int pulseWidth;                                            
volatile boolean interruptFlag;
unsigned long analogReadInterval = 250; //read pots and map
unsigned long lastAnalogRead;

const byte setFallingSwitch = 5;
char risefall = 'R'; //default rising mode

const byte setChargePulseSwitch = 6;
boolean chargePulse = false ;  //default dc powered mode

volatile byte timeSliceCount = 0; //TDC 0 degrees

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
// set the LCD address to 0x3f for a 20 chars 4 line display
// Set the pins on the I2C chip used for LCD connections:
//                    addr, en,rw,rs,d4,d5,d6,d7,bl,blpol
LiquidCrystal_I2C lcd(0x3f, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);  // Set the LCD I2C address

void setup() {
  //Serial.begin(115200);
  //Serial.println("starting...");
  lcd.begin(20, 4); // initialize the lcd for 20 chars 4 lines, turn on backlight
  lcd.setCursor(1, 0); // lcd display setup of unchanging headings
  lcd.print("RPM:"); // print fixed characters
  lcd.setCursor(12, 0);
  lcd.print("Mode:"); //to display code choice R or F
  lcd.setCursor(1, 1);
  lcd.print("Pos:");
  lcd.setCursor(9, 1);
  lcd.print("Width:");
  lcd.setCursor(1, 2);
  lcd.print("Us Delay:");
  lcd.setCursor(1, 3);
  lcd.print("Deg Advance:");

  pinMode(outputPin, OUTPUT); // declare the outputPin as an OUTPUT
  pinMode(chargePin, OUTPUT); // declare the chargePin as an OUTPUT
  pinMode (setFallingSwitch, INPUT_PULLUP); //check for a LOW input to indicate switch is closed to ground
  pinMode(setChargePulseSwitch, INPUT_PULLUP);

  if (digitalRead(setChargePulseSwitch) == LOW)
    chargePulse = true; //AC CDI

  //Timer1 default set up .5ms trigger pulse every 50 ms
  TCCR1A = 0;
  TCCR1B = (1 << WGM12); //CTC mode to OCR1A
  OCR1A = timerTopValue;
  TIMSK1 |= (1 << OCIE1A); //interrupt enable compareA
  TIMSK1 |= (1 << OCIE1B); //interrupt enable compareB
  OCR1B = 125; //sets trigger pulse width, 500 = 2Ms, 250 = 1Ms, 125 = .5Ms, set to 1250 for 5013 cdi ***************
  TCCR1B |= (1 << CS11) | (1 << CS10); //prescaler 64 4us/tick

  //Timer2 default setup charge pulse 12 periods 30 degrees each; only 5 get turned on
  //charge pulse timing interval = Timer1 trigger period/12 = timerTopValue/96
  TCCR2A = 0;
  TCCR2B = 0;
  TCCR2A = 1 << WGM20; //lsb of mode 7 pwm to OCR2A
  TCCR2B = 1 << WGM22; //msb of mode 7 pwm to OCR2A;
  OCR2A = timerTopValue / 96; //96 = 12*4*2 (#periods, prescaler difference, up/down timer mode )
  TIMSK2 = 0;
  TIMSK2 = 1 << TOIE2; //enable overflow interrupt
  // actually start timer in ISR(TIMER1_COMPA_vect
  // to prevent out of sync charge pulse, no prescaler set here

  attachInterrupt(digitalPinToInterrupt(3), delayPeriodTiming, FALLING);

}

void loop()
{
  if (millis() - lastAnalogRead >= analogReadInterval)
  {
    lastAnalogRead += analogReadInterval;
    potValue = analogRead(pot1); //rpm
    pickupValue = analogRead(pot2); // pickup position
    barWidth = analogRead(pot3);  
  
    //Timer2 OCR2A requires max value 255 => 615 lowest RPM
    if (chargePulse)
    {
      RPM = map(potValue, 0, 1023, 615, 10000);  //this section needs 2 pots added to set pickup and pulseWidth **************************
      pickup = 74; //map(pickupValue, 0, 1023, 0, 65); so advance will read based on delay,52 for yamaha 350 2 pu, 74 for 1 pu, 72 for tw200, 25 for 5013
      pulseWidth = (60000000/RPM)/360; //time for 1° in uS
      barWidth = 60; //barWidth = pulseWidth + 1000;  //10 for yamaha 350 2 pu, 60 for 1 pu, 60 for tw200
      //RPM = 615; //for my serial test purposes 615-3800
    }
    else
    {
      RPM = map(potValue, 0, 1023, 500, 3800);
      pickup = 25; //map(pickupValue, 0, 1023, 0, 50); //to set position of pickup so advance will read
      pulseWidth = map(potWidth, 0, 1023, 271, 44); //add Width to non charging case
     // RPM = 500;//for my serial test purposes 500-3800
    }

    timerTopValue = 15000000UL / RPM;
    OCR1B = pulseWidth;

    if (digitalRead(setFallingSwitch) == LOW) //set Falling
    {
      risefall = 'F';
    }
    else
    {
      risefall = 'R';
    }

    lcd.setCursor(6, 0);
    lcd.print("     "); // print blank spaces to clear old data
    lcd.setCursor(6, 0);
    lcd.print(RPM);

    lcd.setCursor(18, 0);
    lcd.print("  ");
    lcd.setCursor(18, 0);
    lcd.print(risefall); //print R or F at upper right side

    lcd.setCursor(6, 1);
    lcd.print("   ");
    lcd.setCursor(6, 1);
    lcd.print(pickup);

    lcd.setCursor(16, 1);
    lcd.print("   ");
    lcd.setCursor(16, 1);
    lcd.print(pulseWidth);

    lcd.setCursor(11, 2);
    lcd.print("       ");
    lcd.setCursor(11, 2);
    lcd.print(copy_delayPeriod);
   
    lcd.setCursor(14, 3);
    lcd.print("      ");
    lcd.setCursor(14, 3);
    lcd.print(delayDegrees, 1);   //delayDegrees, 1);
  }
 
  if (trigger == true && interruptFlag == true )
  {
    trigger = false;
    interruptFlag = false;
    noInterrupts();
    copy_delayPeriod = delayPeriod;
    interrupts();

    delayDegrees = pickup - (360.0 * (copy_delayPeriod) / (timerTopValue * 4.0)); //for decimal place in deg display.
    }
}

ISR(TIMER1_COMPA_vect) {
  OCR1A = (timerTopValue); // value to set delay between pulses to trigger cdi
  digitalWrite(chargePin, LOW); //guarantee off charge pin at trigger
  digitalWrite(outputPin, HIGH); //turn on pin  trigger

  if (risefall == 'R') //switch not set; default Rising trigger
  {
    delayPeriodStart = micros(); //start looking for response as pulse rises
    trigger = true;
  }
  //start Timer 2 for charge pulses
  if (chargePulse)
  {
    timeSliceCount = 0;
    TCNT2 = 0;
    OCR2A = timerTopValue/96; //set 12 periods
    TCCR2B |=  1 << CS22 | 1 << CS21; //prescaleer 256 16us/tick
  }
}

ISR(TIMER1_COMPB_vect) {
  digitalWrite(outputPin, LOW);

  if (risefall == 'F') //switch set for Falling trigger
  {
    delayPeriodStart = micros(); //start looking for response as pulse falls
    trigger = true;
  }
}

void delayPeriodTiming()
{
  delayPeriod = micros() - delayPeriodStart;
  interruptFlag = true;
}

ISR(TIMER2_OVF_vect)
//5 pulses of 30 degrees starting at 60 degrees
//ON at 60,120,180,240,300 = 2,4,6,8,10
//OFF at 90,150,210,270,330 = 3,5,7,9,11
{
  if (timeSliceCount != 0 && timeSliceCount % 2 == 0)
  {
    digitalWrite (chargePin, HIGH);
  }
  else //if (timeSliceCount == 0 || timeSliceCount % 2 == 1)
  {
    digitalWrite(chargePin, LOW);
  }
  timeSliceCount++;

  if (timeSliceCount == 12)
  {
    timeSliceCount = 0;
    //stop Timer2 by clearing prescaler bits
    TCCR2B &= ~1<< CS22;
    TCCR2B &= ~1<< CS21;
  }
}