Automated Fuse Tester - for testing automative fuses using an arduino

fuses.ino

/* 
/ You'll need to adjust the current reading code based on the specific sensitivity of your ACS758 model.
/ Remember to adjust `ACS758_SENSITIVITY` based on the specific ACS758 model you're using. 
/ The `readCurrent()` function reads the current sensor output and converts it to current based on the sensor sensitivity. 
/
/ It's necessary to map the analog voltage reading based on your specific power source and voltage divider setup. 
/ The code provided here assumes a 5V power supply for the Arduino, and that the voltage divider reduces the maximum 
/ voltage of 15V to within 0-5V for the ADC. The specifics will depend on the actual resistors used in the voltage divider.
/ The Aref pin is supplied with 4.3v from a preecision zenner diode.
/
/ Uses a: 
/ K-type thermocouple via a MAX31855 to give 14  bits of temperature.
/ an LCD display (2 rows of 16 chars) via I2C
/ an Allegro ACS758 Linear Current Hall Sensor, to read current.
/ a voltage divider, to read volatage.
/ an opto-coupler (something fast like a 6N137) in paralell to the fuese, to detect the "blown" fuse.
/ a relay to apply power to the Fuse under test.
/ a single SPST momentary button.
/
*/

#include <Wire.h> 
#include <LiquidCrystal_I2C.h>
#include <Adafruit_MAX31855.h>

#define RELAY_PIN 7
#define BUTTON_PIN 2
#define TEST_INPUT_PIN 3
#define VOLTAGE_SENSOR A0
#define CURRENT_SENSOR A1
#define NUM_SAMPLES 50
#define ACS758_SENSITIVITY 40.0 // 40mV/A
/*
          40.0 for ACS758LCB-050B
          60.0 for ACS758LCB-050U
          20.0 for ACS758LCB-100B
          40.0 for ACS758LCB-100U
          13.3 for ACS758KCB-150B
          16.7 for ACS758KCB-150U
          10.0 for ACS758ECB-200B
          20.0 for ACS758ECB-200U 

The quiescent Output voltage is factor for VCC that appears at output when the current is zero. 
 - for Bidirectional sensor it is 0.5 x VCC
 - for Unidirectional sensor it is 0.12 x VCC
 - e.g for model ACS758LCB-050B, the B at the end represents Bidirectional (polarity doesn't matter)
 - e.g for model ACS758LCB-100U, the U at the end represents Unidirectional (polarity must match)

          0.50 for ACS758LCB-050B
          0.12 for ACS758LCB-050U
          0.50 for ACS758LCB-100B
          0.12 for ACS758LCB-100U
          0.50 for ACS758KCB-150B
          0.12 for ACS758KCB-150U
          0.50 for ACS758ECB-200B
          0.12 for ACS758ECB-200U
*/


#define THERMOCOUPLE_DO   4
#define THERMOCOUPLE_CS   5
#define THERMOCOUPLE_CLK  6

Adafruit_MAX31855 thermocouple(THERMOCOUPLE_CLK, THERMOCOUPLE_CS, THERMOCOUPLE_DO);
LiquidCrystal_I2C lcd(0x27, 16, 2); 

volatile unsigned long startTime = 0;
volatile bool testInProgress = false;
volatile bool emergencyStop = false;

void setup() {
  
  lcd.clear();
  lcdText(0, "Ready to Test", 1);
  lcdText(1, "* Push Start *", 1);
  
  pinMode(RELAY_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(TEST_INPUT_PIN, INPUT);
  
  attachInterrupt(digitalPinToInterrupt(BUTTON_PIN), startTest, FALLING);
  attachInterrupt(digitalPinToInterrupt(TEST_INPUT_PIN), endTest, RISING);
  
  // Set external reference voltage
  analogReference(EXTERNAL);
  // alow ADC to settle down
  analogRead (0);
}

void lcdText(int row, String text, int justif){
 
  int offset = 0;
  
  switch(justif){
   
    case(0)://Text left justified
      lcd.setCursor ( offset, row );
      lcd.print(text);
    break;
   
    case(1)://Text centred
      offset = (displayCharLength - text.length())/2;
      lcd.setCursor ( offset, row );
      lcd.print(text);
    break;

    case(2)://Text right justified
      offset = (displayCharLength - text.length());
      lcd.setCursor ( offset, row );
      lcd.print(text);
    break;
   
  }
}


void loop() {
  if (emergencyStop) {
    digitalWrite(RELAY_PIN, LOW);
    testInProgress =  false;
    lcd.clear();
    lcdText(0, "!!EMERGENCY STOP!!", 1);
    lcdText(1, "* RESET POWER *", 1);
    while(1);
  }

  if (testInProgress) {
    double voltage = readVoltage();
    double current = readCurrent();
    double temp = thermocouple.readCelsius();
    
    // Code to display these readings as you need
    // e.g., lcd.setCursor(0, 1); lcd.print("V:" + String(voltage, 2) + " I:" + String(current, 2) + " T:" + String(temp, 2));
 // Update display with temperature, voltage, and current
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("T: " + String(temp) + " C");
  lcd.setCursor(0, 1);
  lcd.print("V: " + String(voltage) + " V  I: " + String(current) + " A");
}
  
  }
}

void startTest() {
  if (!testInProgress) {
    digitalWrite(RELAY_PIN, HIGH);
    startTime = micros();
    testInProgress = true;
  } else {
    digitalWrite(RELAY_PIN, LOW);
    emergencyStop = true;
  }
}

void endTest() {
  if (testInProgress) {
    digitalWrite(RELAY_PIN, LOW);
    unsigned long elapsedTime = micros() - startTime;
    
    // Display elapsed time
    
    
    unsigned int minutes = elapsedTime / 60000000; // Calculate minutes
    elapsedTime %= 60000000; 
    unsigned int seconds = elapsedTime / 1000000; // Calculate seconds
    elapsedTime %= 1000000;
    float fractional_seconds = elapsedTime / 1000000.0; // Calculate fractional seconds

    lcd.clear();
    if(minutes > 0) {
      lcd.print(minutes);
      lcd.print("m ");
    }
    lcd.print(seconds);
    lcd.print(".");
    lcd.print(int(fractional_seconds * 100)); // Print only two decimal places
    lcd.print("s");
    lcd.setCursor(0, 1);
    lcd.print("Press start to clear");
    
    testInProgress = false;
  }
}

// Function to read voltage from sensor
double readVoltage() {
  int raw = analogRead(VOLTAGE_SENSOR);
  return (raw / 1023.0) * 4.3; // Convert raw reading to voltage (max 4.3V)
}

// Function to read current from sensor
double readCurrent() {
  double total = 0;
  for(int i = 0; i < NUM_SAMPLES; i++) {
    int raw = analogRead(CURRENT_SENSOR);
    double voltage = (raw / 1023.0) * 4.3; // Convert raw reading to voltage
    double VQ = 2.5; // quiescent voltage (Vcc/2)
    double deltaV = voltage - VQ; // change in voltage from VQ
    if (deltaV < 0) deltaV = 0; // only measure current in one direction
    double current = (deltaV * 1000.0) / ACS758_SENSITIVITY; // Convert voltage to current
    total += current;
  }
  return total / NUM_SAMPLES; // Return the average current
}

This is a WIP to "test" fuses.