Introduction: Arduino Inductance/Capacitance/Resistance Meter

About: Student of Computer Science, Faculty of Sciences, National Autonomous University of Mexico, I like mechatronics and robotics and programming course, my favorite food is pizza like most, I love pizza

Hello such friends, will show you how to create a measuring inductance, capacitance and resistance using Arduino most commonly the ATmega328P, all programming is thrown into Arduino and components commonly found in our laboratory and will also be very cheap to do so, this meter measures pF to nF and also measuring uH and mH, as well as use a 7805 regulator can be powered from 24V to 6V, I used a 9V battery

Step 1: Material

This is the material to be used.

Integrated:
IC ATMEGA 328P (Arduino UNO / Duemilanove)

LM741

LM393

Regulatory L7805CV

LCD 16X2

Crystal 16MHz

Capacitors:

0.33uF

100nF

2 x 22pF

Polyester 1uF

Resistances:

10K potentiometer

7 x 10K

2 x 220 Ohm

1 M

150 Ohm

330 Ohm

Diodes:

1N4004

Connectors:

Terminal Block 2 pin

4 x MOLEX 100 spent 2 pin

4 pin MOLEX spent 100

4 x Borne

2 x switch

2 x push button chasis

Step 2: Code and Performance

As three functions measuring bone capacitance, inductance and resistance, we must choose we want to do, to choose the function and use 2 bits can count 0-0,0-1,1-0,1-1.

So we use two switch to choose, making them function as a dip switch using them as pull down, to measure inductance is 0-0, 0-1 for capacitance, resistance to 1-0, that's how we choose to measure.

To measure inductance use the LM393 comparator to measure the capacitance the LM741, and to measure resistances easily use a 10k resistor and make a voltage divider.

Suppose we want to calculate R1. We know that R2 has a value of 10k, we know that Vin has a value of 5V (which we usually find in the Arduino environment) and that reading on an analog Vout pin of Arduino is 750.

1.- We know that the resolution of the ADC Arduino is 10 bits, which means that 1024 is possible divisions (2 raised to 10) for an input value between 0V and 5V. So if we put 5V on an analog pin, its value will be 1023 (1024 will not remember that starts counting at 0, not 1); if we put 0V on pin, its value will be 0 and if for example we 2.5V its value will be 511.

Therefore, if the value that gives the reading analog pin in its digital value is 750, we can calculate the Vout, the output voltage of the voltage divider.

>> 5V / 1024 divisions = 0,00488V / division

>> 0.00488 volts / division • 750 divisions = 3.66V

2.-We can already clear R1, that was the question:

>> Vout = (R2 / R1 + R2) • Vin

>> 3.66 V = (10k / R1 + 10k) • 5V

>> R1 + 10k = 10k • 5V / 3.66V

>> R1 = (10k • 5V / 3.66V) - 10k = 3.66KΩ

In general, we can calculate the value of R1 as:

>> R1 = (R2 • Vin / Vout) - R2

The same code is in Spanish documentation, so if you have any questions please say so:

#include LiquidCrystal lcd(13, 8, 7, 5, 4, 2);

#define R_1 A1
#define R_2 A2
#define IND_1 6
#define IND_2 12
#define fuente_pin 11
#define switch_pin 10
#define descarga_pin 9

#define PIN_1 A3
#define PIN_2 A4

//Variables leer pines
int pin_1;
int pin_2;

//Variables para inductometro
double pulso;
double frecuencia;
double capacitancia;
double inductancia;

//Capacimetro
float R = 1.0e6;
float C = 0;
float RC = 0;
long t_inicio = 0;
volatile long t_alto = 0;
long T = 0;
float VCC = 4.50;
float Vref = VCC / 2;
float V0 = 0;
float error_correccion = 40.;
int retardo_delay = 20;

//Variables resistometro
int vR_1 = 0;
int vR_2 = 0;
float Vin = 5;
float Vout = 0;
float Res_1 = 10000;
float Res_2 = 9000000;
float r_1 = 0;
float r_2 = 0;
float Resistor_1[8];
float Resistor_2[5];
float ResArreglo_1;
float ResArreglo_2;

void setup() {
lcd.begin(16, 2);

//Configuracion de pines
pinMode(PIN_1, INPUT);
pinMode(PIN_2, INPUT);
//Configuracion Inductometro
pinMode(IND_1, INPUT);
pinMode(IND_2, OUTPUT);
capacitancia = 0.000001021;
//delay(200);
//Configuracion de Resistometro
pinMode(R_1, INPUT);
pinMode(R_2, INPUT);

//Configuracion Capacimetro
attachInterrupt(1, stop, RISING);
Vref = VCC / 2;
pinMode(fuente_pin, OUTPUT);
digitalWrite(fuente_pin, LOW);
pinMode(switch_pin, INPUT);
pinMode(descarga_pin, INPUT);
}

void loop() {
leerpines();

if (pin_1 == LOW && pin_2 == LOW) {
digitalWrite(IND_2, HIGH);
delay(5);
digitalWrite(IND_2, LOW);

delayMicroseconds(100);

pulso = pulseIn(IND_1, HIGH, 5000);
lcd.clear();
if (pulso > 0.1) {
frecuencia = 1.E6 / (2 * pulso);
inductancia = 1. / (capacitancia * frecuencia * frecuencia * 4.*3.1459 * 3.14159);
inductancia *= 1E6;

lcd.setCursor(2, 0);
lcd.print("INDUCTANCIA:");
//delay(200);
if (inductancia >= 1000) {
lcd.setCursor(0, 1);
int valor = (inductancia / 1000) - 0.5;
lcd.print(valor);
lcd.setCursor(6, 1);
lcd.print("mH");
} else {
lcd.setCursor(0, 1);
int valor_2 = inductancia + 10;
lcd.print(valor_2);
lcd.setCursor(6, 1);
lcd.print("uH");
}
} else if (pulso < 0.1) {
lcd.setCursor(2, 0);
lcd.print("INSERTAR IND");
}
delay(300); } if (pin_1 == LOW && pin_2 == HIGH) {
lcd.clear();
for (int i = 0 ; i <= 7; i++) {
Resistor_1[i] = analogRead(R_1);
ResArreglo_1 = ResArreglo_1 + Resistor_1[i];
}
vR_1 = (ResArreglo_1 / 8.0);
Vout = (Vin * vR_1) / 1023;
r_1 = Res_1 * (1 / ((Vin / Vout) - 1));
lcd.setCursor(2, 0);
lcd.print("RESISTENCIA:");
if (r_1 <= 999) {
lcd.setCursor(0, 1);
lcd.print(r_1);
lcd.setCursor(9, 1);
lcd.print("Omhs");
} else if (r_1 >= 1000) {
r_1 = r_1 / 1000;
lcd.setCursor(0, 1);
lcd.print(r_1);
lcd.setCursor(9, 1);
lcd.print("KOmhs");
}
delay(500);
ResArreglo_1 = 0;
} if (pin_1 == HIGH && pin_2 == LOW) {
lcd.clear();
if (debounce(switch_pin) == LOW)
{
pinMode(descarga_pin, OUTPUT);
digitalWrite(descarga_pin, LOW);
delay(100);
pinMode(descarga_pin, INPUT);
digitalWrite(fuente_pin, HIGH);
t_inicio = micros(); } if (t_alto > 0 && t_inicio > 0 && (t_alto - t_inicio) > 0 )
{
T = (t_alto - t_inicio);
RC = -T / log((Vref - VCC) / (V0 - VCC));
//Vref = VCC/2
//V0 = 0V
C = RC / R; //Valor en uF

lcd.setCursor(0, 0);
lcd.print("C:");
lcd.setCursor(3, 0);
lcd.print(C * 1000, 1);
lcd.setCursor(13, 0);
lcd.print("nF");
lcd.setCursor(0, 1);
lcd.print("C:");
lcd.setCursor(3, 1);
lcd.print(C * 1000000 - error_correccion , 0);
lcd.setCursor(13, 1);
lcd.print("pF"); t_inicio = 0;
t_alto = 0; digitalWrite(fuente_pin, LOW);
delay(2000);
}
}
}void leerpines() {
pin_1 = digitalRead(PIN_1);
pin_2 = digitalRead(PIN_2);
}void stop()
{
t_alto = micros();
}int debounce(int pin)
{
int estado;
int previo_estado;
previo_estado = digitalRead(pin);
for (int i = 0; i < retardo_delay; i++)
{
delay(1);
estado = digitalRead(pin);
if ( estado != previo_estado)
{
i = 0;
previo_estado = estado;
}
}
return estado;
}

Step 3: Circuit, Schematic and Pcb

Here you can see how everything is connected in the schematic, I upload files made with EAGLE.

Hope you find it helpful, any questions or comments let him know, greetings.

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