Arduino Boost Gauge

// Arduino-based Boost Gauge v3
// Uses a SSCDRRN030PDAA5 Honeywell Pressure Sensor connected to an Arduino Uno

#include <LiquidTWI.h>
#include <Wire.h>

int analogInPin = A0;           // Analog input pin that the sensor is attached to
int sensorValue = 0;            // value read from the sensor
int boost = 0;                  // boost value in psi
int boostgraph = 0;             // boost graph value
int calibrationint = 124;       // map boost to ECU MAP sensor
int maxvalue = 0;               //peak boost encountered since last reset
int minvalue = 0;               //peak vacuum encountered since last reset
boolean minmax = false;         //flag for boost graph or max and min boost

// Connect via i2c, default address #0 (A0-A2 not jumpered)
LiquidTWI lcd(0);

void setup() {
  // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);
  // initialize the serial communications:
  Serial.begin(9600);
}

void loop() {
  //backlight on
  lcd.setBacklight(HIGH);
  // read the analog-in value:
  sensorValue = analogRead(analogInPin);
  // map sensorValue to boost with calibration
  boost = map(sensorValue, 0, 1023, -3000, 3000) * calibrationint / 1000;
  // create boost bar graph value
  if (boost < 0) {
    boostgraph = map(boost, -150, 0, 0, 7);
  }
  else {
    boostgraph = map(boost, 0, 200, 7, 15);
  }

  // compute max and min
  if (max(maxvalue, boost) > maxvalue) {
    maxvalue = boost;
  }
  if (min(minvalue, boost) < minvalue) {
    minvalue = boost;
  }

  //set cursor and print first line to LCD, keeping decimal point in same place
  lcd.setCursor(0, 0);
  if (boost > 150) {
    lcd.print("   WARNING!!!   ");
    lcd.setCursor(0,1);
    lcd.print("DANGERTOMANIFOLD");
  }
  else {
  lcd.print("Boost:");
  if (boost < -99) {
    lcd.print("");
  }
  else if (boost < 0) {
    lcd.print(" ");
  }
  else if (boost < 100) {
    lcd.print("  ");
  }
  else {
    lcd.print(" ");
  }
  lcd.print(boost / 10);
  lcd.print(".");
  int deci = boost % 10;
  lcd.print(abs(deci));
  lcd.print(" psi   ");  //extra space to clear any extra characters

  // set cursor to second line on LCD
  lcd.setCursor(0,1);

  if (minmax == true) {
  // print max and min boost
  lcd.print(maxvalue / 10);
  lcd.print(".");
  int maxdeci = maxvalue % 10;
  lcd.print(abs(maxdeci));
  lcd.print(", ");
  lcd.print(minvalue / 10);
  lcd.print(".");
  int mindeci = minvalue % 10;
  lcd.print(abs(mindeci));
  lcd.print("    ");   // extra space to clear any extra characters
  }
  else {
    // print boost graph
    for (int cursorpos = 0; cursorpos < boostgraph; cursorpos++) {
      lcd.setCursor(cursorpos, 1);
      lcd.print((char)255);
    }
    for (int cursorpos = (int)boostgraph; cursorpos < 17; cursorpos++) {
      lcd.setCursor(cursorpos, 1);
      lcd.print("-");
    }
  }
}
  // wait 2 milliseconds before the next loop
  // for the analog-to-digital converter to settle
  // after the last reading:
  delay(2);
}