Problems interfacing with arduino uno and nano

Projects General Guidance
1

i want to use the code arduino uno to arduino nano to build votage indicator but it did not get the same result as arduino uno because the input & output voltage is different and the led did not light up according to condition. can someone help me to fix this problem? here is my code:

// include the library code:
#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(7, 6, A0, A1, A2, A3);

int analogPin = A4;
float vout = 0.0;
float vin = 0.0;
float R1 = 100000.0; // resistance of R1 (100K)
float R2 = 10000.0; // resistance of R2 (10K)
int value = 0;
int a[5] = {};

int greenLed = 10;
int blueLed = 11;
int yellowLed = 12;
int redLed = 13;
int sound = 8; 

void setup() 
{
  pinMode(greenLed, OUTPUT);
  pinMode(blueLed, OUTPUT);
  pinMode(yellowLed,OUTPUT);
  pinMode(redLed,OUTPUT);
  
  pinMode(A0,OUTPUT);
  pinMode(A1,OUTPUT);
  pinMode(A2,OUTPUT);
  pinMode(A3,OUTPUT);
  
  pinMode(A4,INPUT);
  
  Serial.begin(9600);
  lcd.begin(16, 2);
  lcd.setCursor(1, 0);
  lcd.print("VOLT INDICATOR");
  lcd.setCursor(6, 1);
  lcd.print("BLIS");
  delay(3000);
  lcd.clear(); 
}

void loop() 
{
 // LCD DISPLAY
  
 lcd.print("Voltage Level"); 
 // read the value at analog input
 value = analogRead(A4);
 vout = (value * 5) / 1024.0;
 vin = vout / (R2 / (R1 + R2));
 Serial.println (vin);
  
 if (vin < 0.09)
 {
  vin = 0.0;
 }
 
 lcd.setCursor(0, 1);
 lcd.print("Voltage V :");
 lcd.print(vin);
 delay(3000);
 //lcd.clear();
 
// LED & BUZZER
  
if(vin <= 11.3)
{
 digitalWrite(redLed, HIGH);
 //delay (1000);
 tone(sound, 1000, 250);              
 delay(1000);                              
 digitalWrite(redLed, LOW);
 //delay (1000);
 tone(sound, 2000, 250);             
 delay(1000);                                
}
  
  if(vin <= 11.60 && vin > 11.3) 
{
 digitalWrite(greenLed,LOW);
 digitalWrite(blueLed,LOW);
 digitalWrite(yellowLed,HIGH);
 digitalWrite(redLed,HIGH);
}
  
  if(vin <= 12.1 && vin > 11.6) 
{
  digitalWrite(greenLed,LOW);
  digitalWrite(blueLed,HIGH);
  digitalWrite(yellowLed,HIGH);
  digitalWrite(redLed,HIGH);
}

if(vin > 12.1) 
{
  digitalWrite(greenLed,HIGH);
  digitalWrite(blueLed,HIGH);
  digitalWrite(yellowLed,HIGH);
  digitalWrite(redLed,HIGH);
}
}

nano.PNG

2

Hi,
Welcome to the forum.

Please read the post at the start of any forum , entitled "How to use this Forum".
OR
http://forum.arduino.cc/index.php/topic,148850.0.html.
Then look down to item #7 about how to post your code.
It will be formatted in a scrolling window that makes it easier to read.

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Both circuits would be good.

Thanks.. Tom... :slight_smile:

3

If you are powering the Nano from the USB connector, there is a reverse voltage diode in series that drops about 0.3 volts, so the analog reference voltage (AREF) is about 4.7 volts instead of 5V.
Change:

vout = (value * 5) / 1024.0;

To:

vout = (value * 4.7) / 1024.0;

And try it.

4

TomGeorge:
Hi,
Welcome to the forum.

Please read the post at the start of any forum , entitled "How to use this Forum".
OR
http://forum.arduino.cc/index.php/topic,148850.0.html.
Then look down to item #7 about how to post your code.
It will be formatted in a scrolling window that makes it easier to read.

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Both circuits would be good.

Thanks.. Tom... :slight_smile:

thanks for the suggestion :slight_smile: . the input voltage of pictures that i attach is vin = 11v

nano.PNG

uno.PNG
uno.PNG811×515 11.6 KB

5

JCA34F:
If you are powering the Nano from the USB connector, there is a reverse voltage diode in series that drops about 0.3 volts, so the analog reference voltage (AREF) is about 4.7 volts instead of 5V.
Change:

vout = (value * 5) / 1024.0;

To:

vout = (value * 4.7) / 1024.0;

And try it.

i already try it but it still does not work. i attach the picture of my project simulation when it use value 4.7 and 5.

nano 2.PNG

nano.PNG

6

Hi,
Are you just running simulations?

Have you built any hardware and tried your code?
Can I suggest you get down and dirty your hands and BUILD your project in REAL life, then see what you get.

If you have to use the simulation, put a virtual voltmeter on A4 and check the actual voltage going into the controller.

Tom...... :slight_smile: