So I'm a newbie and I've built a little project, a temperature sensor lm35 connected to my arduino uno and LCD I2C that show what's the temperature in celsius and fahrenheit, but I'm having problems.
It doesn't work properly, it shows different temperature every few seconds, from around 0.003 to around 5-15 to around 20-30.
The amount of seconds is the same as the delay command I write in the code, at the end of this code there is a delay(5000) and the numbers change every 5 seconds, if I change it to delay(3000) the numbers change every 3 seconds.
I don't know if the issue is in the code or if I just built it wrong.
//load libraries
#include <Wire.h>
#include <LCD.h>
#include <LiquidCrystal_I2C.h>
//Define variables for the LCD
#define I2C_ADDR 0x3F //Define I2C Address
#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
//define variables for the LM35 temperature sensor
float temp; //Define the temp float variable
float tempf; //Define the Fahrenheit float variable
int sensor = 0; // sensor middle pin on analog pin 0
//Initialise the LCD
LiquidCrystal_I2C lcd(0x3F, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);
void setup()
{
//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("Temp C = ");
//goto first column (column 0) and second line (line 1)
lcd.setCursor(0,1);
//Print at cursor Location
lcd.print("Temp F = ");
}
void loop()
{
temp = analogRead(sensor); //assigning the analog output to temp
temp = temp * 0.48828125; //converting volts to degrees celsius ----- 0.48828125 = [(5V*1000)/1024]10
tempf = (temp * 1.8)+32; //Converting from celsius to Fahrenheit
lcd.setCursor(8,0); //move the cursor to position 8 on row 1
lcd.print(temp); //print the temperature in Celsius
lcd.setCursor(8,1); //move the cursor to position 8 on row 2
lcd.print(tempf); //print the temperature in Fahrenheit
delay(5000);
}
If it was backwards before it might be dead. Don't take my word from my interpretation of a fritzing picture. Get the data sheet and make sure of the pinout (page 3) before you connect it.
groundfungus:
If it was backwards before it might be dead. Don't take my word from my interpretation of a fritzing picture. Get the data sheet and make sure of the pinout (page 3) before you connect it.
The pinout is ok.
Probably a silly question, the middle pin (which is the output of the sensor) is connected to A0 on the arduino, where is it mentioned in the code?
By frequencies I mean the numbers of acquisition you do in a second! You can have a sensor for which u have 4 acquisitions per second (4Hz) and another with another acquisiton frequency.
What delay does to arduino is that it stops the arduino from running other code, it just freezes - for professional purposes this is not good!
The code is the following (see if you understand :)):
unsigned long current = 0;
void loop()
{
if(millis() - current >= 5000){
current = millis();
temp = analogRead(sensor); //assigning the analog output to temp
temp = temp * 0.48828125; //converting volts to degrees celsius ----- 0.48828125 = [(5V*1000)/1024]10
tempf = (temp * 1.8)+32; //Converting from celsius to Fahrenheit
lcd.setCursor(8,0); //move the cursor to position 8 on row 1
lcd.print(temp); //print the temperature in Celsius
lcd.setCursor(8,1); //move the cursor to position 8 on row 2
lcd.print(tempf); //print the temperature in Fahrenheit
}
}
