Srijal Poojari
Published © CC BY-NC-SA

The Companion IC

The Companion IC is a very cool looking Clock + Ohmmeter + Capacitance Meter + Diode Tester!

EasyFull instructions provided5,530
The Companion IC

Things used in this project

Hardware components

Arduino Nano R3
Arduino Nano R3
×1
USB-A to Mini-USB Cable
USB-A to Mini-USB Cable
×1
Resistor 10k ohm
Resistor 10k ohm
2x 220 ohm resistor 1x (1k, 4.7k, 47k, 100k) ohm resistors
×4
Single Turn Potentiometer- 10k ohms
Single Turn Potentiometer- 10k ohms
×1
Pushbutton switch 12mm
SparkFun Pushbutton switch 12mm
×2
Slide Switch
Slide Switch
×3
Female Header 8 Position 1 Row (0.1")
Female Header 8 Position 1 Row (0.1")
×4
Male-Header 36 Position 1 Row- Long (0.1")
Male-Header 36 Position 1 Row- Long (0.1")
×2
RGB Backlight LCD - 16x2
Adafruit RGB Backlight LCD - 16x2
×1
4xAA battery holder
4xAA battery holder
×1

Hand tools and fabrication machines

Soldering iron (generic)
Soldering iron (generic)
Hot glue gun (generic)
Hot glue gun (generic)

Story

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Schematics

Main schematic

Code

Code snippet #1

Plain text
//Analog pin used to find resistance

int Apin=7;

//values of r1 to r5
float r1=1000;
float r2=4700;
float r3=10000;
float r4=47000;
float r5=100000;

//pins of r1 to r5
int r1_pin=2;
int r2_pin=3;
int r3_pin=4;
int r4_pin=5;
int r5_pin=6;


float reading=0; //read from analog pin and store here
float R=0;       //calculate unknown and store here

String finalR;   //final value to be displayed along with units

int caseno;   //for debugging, stores the case number
              // we divide the entire range into cases and assign each a number,
              // total 5 cases
              // case1 : less than 2850
              // case2 : 2850  to   7350
              // case3 : 7350  to   28500
              // case4 : 28500 to   73500
              // case5 : more than 73500

#include <stdlib.h> // needed for converting float to string, 
                     //has the String(float,n) function. Explained below.

void setup() {
 Serial.begin(9600);

}

void loop() {

  //first we find unknown resistance using 1kOhm resistor
  //Therefore, disable R2, R3, R4 and R5
   digitalWrite(r2_pin, LOW);   //turn each pin to LOW before setting it as INPUT
   pinMode(r2_pin, INPUT);      // turning it to INPUT when its HIGH enables the 
                                // internal pullup resistor 
     
   digitalWrite(r3_pin, LOW);
   pinMode(r3_pin, INPUT);
   
   digitalWrite(r4_pin, LOW);
   pinMode(r4_pin, INPUT);
  
   digitalWrite(r5_pin, LOW);
   pinMode(r5_pin, INPUT);
   
   pinMode(r1_pin, OUTPUT);
   digitalWrite(r1_pin, HIGH);  

 
   //read and calculate resistance
   reading=analogRead(Apin);
   R=(reading*r1)/(1023-reading);

   // if value < 2850, finalR = value(using 1kOhm)
  if(R<2850){
    
    caseno=1;
    
      if(R<1000){ //if value less than 1000 use "Ohm" not "kOhm"                   
      finalR = String(R,2) + "Ohm";  //String(float,n) Converting float to string 
                                     //with n digits after decimal
                                     // attach "Ohm" after value to the string, 
                                     //'+' joins two strings here
    }
    else{ //use "kOhm
      R=R/1000;
      finalR = String(R,2) + "kOhm";
    }
  }

  
  //if value between 2850 and 7350 , use value obtained by 4.7kOhm 
  else if(R>=2850 && R<7350){
     caseno=2; 
     
   digitalWrite(r1_pin, LOW);  //Enable only 4.7kOhm
   pinMode(r1_pin, INPUT);
     
   digitalWrite(r3_pin, LOW);
   pinMode(r3_pin, INPUT);
   
   digitalWrite(r4_pin, LOW);
   pinMode(r4_pin, INPUT);
  
   digitalWrite(r5_pin, LOW);
   pinMode(r5_pin, INPUT);
   
   pinMode(r2_pin, OUTPUT);
   digitalWrite(r2_pin, HIGH);
   
   reading=analogRead(Apin);  
   R=(reading*r2)/(1023-reading)/1000;
   finalR = String(R,2) + "kOhm"; 
   
  }

  //if value between 7350 and 28500, use value obtained by 10kOhm
  else if(R>=7350 && R<28500){
      caseno=3;
      
   digitalWrite(r1_pin, LOW);
   pinMode(r1_pin, INPUT);
     
   digitalWrite(r2_pin, LOW);
   pinMode(r2_pin, INPUT);
   
   digitalWrite(r4_pin, LOW);
   pinMode(r4_pin, INPUT);
  
   digitalWrite(r5_pin, LOW);
   pinMode(r5_pin, INPUT);
   
   pinMode(r3_pin, OUTPUT);
   digitalWrite(r3_pin, HIGH);

   reading=analogRead(Apin); 
   R=(reading*r3)/(1023-reading)/1000;
   finalR= String(R,2) + "kOhm";
  }
  
  //if value between 28500 and 73500, use value obtained by 47kOhm
  else if(R>=28500 && R<73500){
       caseno=4;
       
   digitalWrite(r1_pin, LOW);
   pinMode(r1_pin, INPUT);
     
   digitalWrite(r2_pin, LOW);
   pinMode(r2_pin, INPUT);
   
   digitalWrite(r3_pin, LOW);
   pinMode(r3_pin, INPUT);
  
   digitalWrite(r5_pin, LOW);
   pinMode(r5_pin, INPUT);
   
   pinMode(r4_pin, OUTPUT);
   digitalWrite(r4_pin, HIGH);

   reading=analogRead(Apin); 
   R=(reading*r4)/(1023-reading)/1000;
   finalR = String(R,2) + "kOhm";

  }

  //if value more than 73500, use value obtained by 100kOhm
  else if(R>=73500){
       caseno=5;
       
   digitalWrite(r1_pin, LOW);
   pinMode(r1_pin, INPUT);
     
   digitalWrite(r2_pin, LOW);
   pinMode(r2_pin, INPUT);
   
   digitalWrite(r3_pin, LOW);
   pinMode(r3_pin, INPUT);
  
   digitalWrite(r4_pin, LOW);
   pinMode(r4_pin, INPUT);
   
   pinMode(r5_pin, OUTPUT);
   digitalWrite(r5_pin, HIGH);

   reading=analogRead(Apin);   
   R=(reading*r5)/(1023-reading)/1000;
   finalR = String(R,2) + "kOhm" ;

  }
   
   Serial.println(finalR); //printing the final string with units
   Serial.println(" ");

   delay(1000);
 
}

Code snippet #2

Plain text
/*  RCTiming_capacitance_meter
 *  code concept taken from Paul Badger 2008
 *  
 *    The capacitor's voltage at one time constant is defined as
 *    63.2% of the charging voltage.
 *    i.e, A Capacitor is filled to 63.2% of its total capacity in 
 *    1 Time Constant
 */

 int analogPin=0 ;         // analog pin for measuring capacitor voltage
 int chargePin=7 ;        // pin to charge the capacitor - connected to
                          // one end of the charging resistor
 int dischargePin=12 ;        // pin to discharge the capacitor, 
                              // same used for diode test(checkPin1)
 float resistorValue=10000.0;   // We use 10kOhm resistor
                                  
 unsigned long startTime;
 unsigned long elapsedTime;
 float microFarads;                // floating point variable to preserve precision
 float nanoFarads;

void setup(){

  pinMode(chargePin, OUTPUT);     // set chargePin to output
  digitalWrite(chargePin, LOW);  

  Serial.begin(9600);             // initialize serial transmission for debugging
}

void loop(){
 
  digitalWrite(chargePin, HIGH);  // set chargePin HIGH and capacitor charging
  startTime = millis();

  while(analogRead(analogPin) < 648){  // just wait and do nothing till 648 
                                       // 647 is 63.2% of 1023,
                                       // which corresponds to full-scale voltage 
  }

  elapsedTime= millis() - startTime;
 // convert milliseconds to seconds ( 10^-3 ) 
 // and Farads to microFarads ( 10^6 ),  net 10^3 (1000)  

  microFarads = ((float)elapsedTime / resistorValue) * 1000;  
  // (float) converts "unsigned long" elapsed time to float

  Serial.print(elapsedTime);       // print the value to serial port
  Serial.print(" mS    ");         // print units


  if (microFarads > 1){
    Serial.print((long)microFarads);       // print the value to serial port
    Serial.println(" microFarads");         // print units
  }
  else
  {
    // if value is smaller than one microFarad, convert to nanoFarads (10^-9 Farad). 

    nanoFarads = microFarads * 1000.0; // multiply by 1000 to convert to nanoFarads (10^-9 Farads)
    Serial.print((long)nanoFarads);    // print the value to serial port
    Serial.println(" nanoFarads");     // print units
  }

  /* dicharge the capacitor  */
  digitalWrite(chargePin, LOW);           // set charge pin to  LOW 
  pinMode(dischargePin, OUTPUT);          // set discharge pin to output 
  digitalWrite(dischargePin, LOW);        // set discharge pin LOW 
  while(analogRead(analogPin) > 0){       // wait until capacitor is completely discharged
  }

  pinMode(dischargePin, INPUT);           // set discharge pin back to input
}

Code snippet #3

Plain text
String state = "null"; //prints "null" for reverse bias or nothing connected

int checkPin1 = 12;
int checkPin2 = 6;


void setup() {
  Serial.begin(9600);

}

void loop() {

pinMode(checkPin1, OUTPUT); 
digitalWrite(checkPin1, LOW); //pin 11 is set to low

//analog read is normally pulled up by the 10k resistor, so null reading is 1023
//In forward bias, the analog pin gets connected to checkPin1, which is LOW. So reading less than 1023
//Practically a small current flows in reverse bias as well, so we take 700 to differentiate

  if(analogRead(checkPin2)<700){ 
    state="forward";
   
  }
 

 Serial.println(state);
 Serial.println(analogRead(checkPin2));
 state = "null";
 delay(500);


}

Code snippet #4

Plain text
// Date and time functions using a DS1307 RTC connected via I2C and Wire lib
#include 
#include 


RTC_DS1307 rtc;//creating "rtc" object of RTC_DS1307, objects are used to access functions
                //more on objects and classes: https://www.youtube.com/watch?v=ABRP_5RYhqU

char daysOfTheWeek[7][12] = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};

void setup () {

  Serial.begin(9600);
  rtc.begin();
   

    // following line sets the RTC to the date & time this sketch was compiled
    // rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
    
    // This line sets the RTC with an explicit date & time, for example to set
    // January 21, 2014 at 3am you would call:
    // rtc.adjust(DateTime(2014, 1, 21, 3, 0, 0));
}

void loop () {
    DateTime now = rtc.now();
    
    Serial.print(now.year());
    Serial.print('/');
    Serial.print(now.month());
    Serial.print('/');
    Serial.print(now.day());
    Serial.print(" (");
    Serial.print(daysOfTheWeek[now.dayOfTheWeek()]);
    Serial.print(") ");
    Serial.print(now.hour());
    Serial.print(':');
    Serial.print(now.minute());
    Serial.print(':');
    Serial.print(now.second());
    Serial.println();
    
    Serial.println();
    delay(1000);
}

Github

https://github.com/adafruit/RTClib

Credits

Srijal Poojari

Srijal Poojari

1 project • 5 followers
I love making! Electronics, science or craft.

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