// This is used with a 4-1/2 digit led voltmeter to operate
// 4 range changing relays, and operate the decimal point
// on a ICL7135 Ikegawa meter (gift from Thor Ourston)
// It had a blown power supply module which was replaced
byte overStatus = 0;
byte underStatus = 0;
const int overRange = 11;
const int underRange = 12;
int pin = 2;

void setup() {   //  4 pins for relay coils and 4 for decimal points
pinMode(2, OUTPUT); // highest range coil, 1999v
pinMode(3, OUTPUT);
pinMode(4, OUTPUT);
pinMode(5, OUTPUT); // lowest range coil, 1.9999v
pinMode(6, OUTPUT); // highest range decimal point
pinMode(7, OUTPUT);
pinMode(8, OUTPUT);
pinMode(9, OUTPUT); // lowest range decimal point
pinMode(11, INPUT); // 2 inputs for under and over range from ICL7135
pinMode(12, INPUT);
digitalWrite(pin, HIGH); // set for highest range
delay (1000);
}

void loop() {

// change pin only if over or under range

Status();

if(underStatus == HIGH && pin < 5) { 
  pin = pin + 1;
 digitalWrite(pin, HIGH); // set for lower range
 digitalWrite(pin-1, LOW);
 }
 
 Status();
 
 if(overStatus == HIGH && pin > 2) {
  pin = pin - 1;
  digitalWrite(pin, HIGH); // set for higher range
  digitalWrite(pin+1, LOW);
 }
}

void Status(){
if(pin == 2){    // set decimal point according to relay selected
digitalWrite(6, LOW);
digitalWrite(7, HIGH);
digitalWrite(8, HIGH);
digitalWrite(9, HIGH);
}
if(pin == 3){
digitalWrite(6, HIGH);
digitalWrite(7, LOW);
digitalWrite(8, HIGH);
digitalWrite(9, HIGH);
}
if(pin == 4){
digitalWrite(6, HIGH);
digitalWrite(7, HIGH);
digitalWrite(8, LOW);
digitalWrite(9, HIGH);
}
if(pin == 5){
digitalWrite(6, HIGH);
digitalWrite(7, HIGH);
digitalWrite(8, HIGH);
digitalWrite(9, LOW);
}
delay (500);
overStatus= digitalRead(overRange);
underStatus=digitalRead(underRange);
}