Ohm meter with Arduino Uno

Measure and display an unknown resistance using Arduino uno

Feb 13, 2020

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39388 views

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11 respects

resistors

potensiometer

Components and supplies

Rotary potentiometer (generic)

RGB LCD Shield Kit, 16x2 Character Display

Jumper wires (generic)

Breadboard (generic)

Arduino UNO

Project description

Code

Untitled file

c_cpp

1/*
2The program reads the analog values of A0. These values are in the   range of 0-1023. 
3*/
4
5#include <LiquidCrystal_I2C.h>
6#include <LCD.h>
7
8#define   analogInput A0
9#define R1 220
10#define vin 5
11#define BACKLIGHT_PIN 3
12#define   En_pin             2
13#define Rw_pin             1
14#define Rs_pin             0
15#define   D4_pin             4
16#define D5_pin             5
17#define D6_pin             6
18#define   D7_pin             7
19
20LiquidCrystal_I2C lcd(0x27, En_pin,Rw_pin,Rs_pin,D4_pin,D5_pin,D6_pin,D7_pin);
21
22void   setup() {
23 
24  Serial.begin(9600); 
25  
26}
27
28void loop() {
29  int   sensorValue=analogRead(analogInput);
30  float voltage=sensorValue*(5.0/1023.0);
31   screen(String(resistance(voltage)));
32  delay(3000); 
33}
34
35int resistance(float   vout){
36  return R1*(1/(vin/vout-1));
37}
38
39void screen(String text){
40   //Define the LCD as 16 column by 2 rows 
41    lcd.begin (16,2);
42    
43     //Switch on the backlight
44    lcd.setBacklightPin(BACKLIGHT_PIN,POSITIVE);
45     lcd.setBacklight(HIGH);
46    
47    //goto first column (column 0) and first   line (Line 0)
48    lcd.setCursor(0,0);
49    
50    //Print at cursor Location
51     lcd.print("Resistor value is: ");
52
53    //goto second column and first   line
54    lcd.setCursor(0,1);
55    lcd.print(text);
56    lcd.print(" ohm");
57   
58}

/*
The program reads the analog values of A0. These values are in the   range of 0-1023. 
*/

#include <LiquidCrystal_I2C.h>
#include <LCD.h>

#define   analogInput A0
#define R1 220
#define vin 5
#define BACKLIGHT_PIN 3
#define   En_pin             2
#define Rw_pin             1
#define Rs_pin             0
#define   D4_pin             4
#define D5_pin             5
#define D6_pin             6
#define   D7_pin             7

LiquidCrystal_I2C lcd(0x27, En_pin,Rw_pin,Rs_pin,D4_pin,D5_pin,D6_pin,D7_pin);

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

void loop() {
  int   sensorValue=analogRead(analogInput);
  float voltage=sensorValue*(5.0/1023.0);
   screen(String(resistance(voltage)));
  delay(3000); 
}

int resistance(float   vout){
  return R1*(1/(vin/vout-1));
}

void screen(String text){
   //Define the LCD as 16 column by 2 rows 
    lcd.begin (16,2);
    
     //Switch on the backlight
    lcd.setBacklightPin(BACKLIGHT_PIN,POSITIVE);
     lcd.setBacklight(HIGH);
    
    //goto first column (column 0) and first   line (Line 0)
    lcd.setCursor(0,0);
    
    //Print at cursor Location
     lcd.print("Resistor value is: ");

    //goto second column and first   line
    lcd.setCursor(0,1);
    lcd.print(text);
    lcd.print(" ohm");
   
}

Untitled file

c_cpp

1/*
2The program reads the analog values of A0. These values are in the  range of 0-1023. 
3*/
4
5#include <LiquidCrystal_I2C.h>
6#include <LCD.h>
7
8#define  analogInput A0
9#define R1 220
10#define vin 5
11#define BACKLIGHT_PIN 3
12#define  En_pin             2
13#define Rw_pin             1
14#define Rs_pin             0
15#define  D4_pin             4
16#define D5_pin             5
17#define D6_pin             6
18#define  D7_pin             7
19
20LiquidCrystal_I2C lcd(0x27, En_pin,Rw_pin,Rs_pin,D4_pin,D5_pin,D6_pin,D7_pin);
21
22void  setup() {
23 
24  Serial.begin(9600); 
25  
26}
27
28void loop() {
29  int  sensorValue=analogRead(analogInput);
30  float voltage=sensorValue*(5.0/1023.0);
31  screen(String(resistance(voltage)));
32  delay(3000); 
33}
34
35int resistance(float  vout){
36  return R1*(1/(vin/vout-1));
37}
38
39void screen(String text){
40  //Define the LCD as 16 column by 2 rows 
41    lcd.begin (16,2);
42    
43    //Switch on the backlight
44    lcd.setBacklightPin(BACKLIGHT_PIN,POSITIVE);
45    lcd.setBacklight(HIGH);
46    
47    //goto first column (column 0) and first  line (Line 0)
48    lcd.setCursor(0,0);
49    
50    //Print at cursor Location
51    lcd.print("Resistor value is: ");
52
53    //goto second column and first  line
54    lcd.setCursor(0,1);
55    lcd.print(text);
56    lcd.print(" ohm");
57  
58}

/*
The program reads the analog values of A0. These values are in the  range of 0-1023. 
*/

#include <LiquidCrystal_I2C.h>
#include <LCD.h>

#define  analogInput A0
#define R1 220
#define vin 5
#define BACKLIGHT_PIN 3
#define  En_pin             2
#define Rw_pin             1
#define Rs_pin             0
#define  D4_pin             4
#define D5_pin             5
#define D6_pin             6
#define  D7_pin             7

LiquidCrystal_I2C lcd(0x27, En_pin,Rw_pin,Rs_pin,D4_pin,D5_pin,D6_pin,D7_pin);

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

void loop() {
  int  sensorValue=analogRead(analogInput);
  float voltage=sensorValue*(5.0/1023.0);
  screen(String(resistance(voltage)));
  delay(3000); 
}

int resistance(float  vout){
  return R1*(1/(vin/vout-1));
}

void screen(String text){
  //Define the LCD as 16 column by 2 rows 
    lcd.begin (16,2);
    
    //Switch on the backlight
    lcd.setBacklightPin(BACKLIGHT_PIN,POSITIVE);
    lcd.setBacklight(HIGH);
    
    //goto first column (column 0) and first  line (Line 0)
    lcd.setCursor(0,0);
    
    //Print at cursor Location
    lcd.print("Resistor value is: ");

    //goto second column and first  line
    lcd.setCursor(0,1);
    lcd.print(text);
    lcd.print(" ohm");
  
}

Downloadable files

Complete circuit

Comments

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creeper_3

3 years ago

Hello, I have a bunch of faded blue resistors in a box that I need to measure, and I was wondering what the potentiometer is actually doing in this circuit.

Anonymous user

2 years ago

The potentiometer in this project simply acting as a rheostat (variable resistor). I guess so, xristos_xatz mixed together with an another project. There are some mistakes. 1., Z isn't properly used here, as impedance (Z) is a complex number because of the frequency, whould be more appropriate simply using R1 and R2 in a DC system. 2., on the component list is 2x16LCD which will not work properly, because of the first row "Resistor value is:" itself an 18 long character chain. On the attached pictures is a 4x20 LCD.

xristos_xatz

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3 Projects

Intro

Components and supplies

Project description

Code

Downloadable files