'lcd ' was not declared in this scope

boice77 · October 4, 2018, 4:23pm

I'm using LCD 1602A 16x2 and I tried installing several sketches but it still shows that error code.
And if anyone sees any mistake in the code please tell
I got this from the internet and did several changes but there are still many errors

this is the code i'm using

#include <Streaming.h>

#include <Adafruit_Sensor.h>

#include <DHT.h>
#include <DHT_U.h>

#include <LiquidCrystal.h>

// Pin connected to the sensor data pin
#define DHTPIN 7

// Display pins
LiquidCrystal LCD (12, 11, 5, 4, 3, 2);

// Use the line according to the sensor model
// #define DHTTYPE DHT11 // Sensor DHT11
#define DHTTYPE DHT22 //DHT Sensor 22 (AM2302)
// #define DHTTYPE DHT21 // DHT Sensor 21 (AM2301)

// Definitions sensor: pin, type
DHT DHT (DHTPIN, DHTTYPE);

// Array symbol degree
byte level [8] = {B00001100,
 B00010010,
 B00010010,
 B00001100,
 B00000000,
 B00000000,
 B00000000,
 B00000000,
 };

void setup ()
{
 // Initialize the display
 lcd.begin (16, 2);
 lcd.clear ();
 // Create the custom character with the symbol of the degree
 lcd.createChar (0, degree);
 // Information on the initial display
 lcd.setCursor (0, 0);
 lcd.print ("Temp. : ");
 lcd.setCursor (13.0);
 // Shows the symbol of the degree
 lcd.write (byte (0));
 lcd.print ("C");
 lcd.setCursor (0.1);
 lcd.print ("Humid. : ");
 lcd.setCursor (14.1);
 lcd.print ("%");

 Serial.begin (9600);
 Serial.println ("Waiting for data ...");
 // Starts DHT sensor
 dht.begin ();
}

void loop ()
{
 // Wait 2 seconds between the measurements
 delay (2000);

 // Moisture reading
 h = dht.readHumidity float ();
 // Reading of temperature (Celsius)
 t = dht.readTemperature float ();

 // Check if the sensor is responding
 if (isnan (h) || isnan (t))
 {
 Serial.println ("Failed to read DHT sensor data !!!");
 return;
 }

 // Display the temperature in the serial monitor and display
 Serial.print ("Temperature: ");
 Serial.print (t);
 lcd.setCursor (8.0);
 lcd.print (t);
 Serial.print (" C * ");
 // Show the moisture in the serial monitor and display
 Serial.print ("humidity: ");
 Serial.print (h);
 Serial.println (" %");
 lcd.setCursor (8.1);
 lcd.print (h);
}

and below is the error code

C:\Users\Lenovo\Documents\Arduino\Probes_Arduino_LCD_1206A_DHT22\Probes_Arduino_LCD_1206A_DHT22.ino: In function 'void setup()':

Probes_Arduino_LCD_1206A_DHT22:38: error: 'lcd' was not declared in this scope

  lcd.begin (16, 2);

  ^

Probes_Arduino_LCD_1206A_DHT22:41: error: 'degree' was not declared in this scope

  lcd.createChar (0, degree);

                     ^

Probes_Arduino_LCD_1206A_DHT22:57: error: 'dht' was not declared in this scope

  dht.begin ();

  ^

C:\Users\Lenovo\Documents\Arduino\Probes_Arduino_LCD_1206A_DHT22\Probes_Arduino_LCD_1206A_DHT22.ino: In function 'void loop()':

Probes_Arduino_LCD_1206A_DHT22:66: error: 'h' was not declared in this scope

  h = dht.readHumidity float ();

  ^

Probes_Arduino_LCD_1206A_DHT22:66: error: 'dht' was not declared in this scope

  h = dht.readHumidity float ();

      ^

Probes_Arduino_LCD_1206A_DHT22:68: error: 't' was not declared in this scope

  t = dht.readTemperature float ();

  ^

Probes_Arduino_LCD_1206A_DHT22:80: error: 'lcd' was not declared in this scope

  lcd.setCursor (8.0);

  ^

Using library LCD_I2C_lib-master in folder: C:\Users\Lenovo\Documents\Arduino\libraries\LCD_I2C_lib-master (legacy)
Using library Adafruit_Unified_Sensor at version 1.0.2 in folder: C:\Users\Lenovo\Documents\Arduino\libraries\Adafruit_Unified_Sensor 
Using library DHT_sensor_library-1.3.0 at version 1.3.0 in folder: C:\Users\Lenovo\Documents\Arduino\libraries\DHT_sensor_library-1.3.0 
Using library LiquidCrystal at version 1.0.7 in folder: C:\Program Files (x86)\Arduino\libraries\LiquidCrystal 
Using library Wire at version 1.0 in folder: C:\Program Files (x86)\Arduino\hardware\arduino\avr\libraries\Wire 
exit status 1
'lcd' was not declared in this scope

UKHeliBob · October 4, 2018, 4:28pm

LiquidCrystal LCD (12, 11, 5, 4, 3, 2);

Declares an object named LCD

lcd.begin (16, 2);

Tries to use an object named lcd

Spot the difference in the names of the objects

boice77 · October 5, 2018, 10:08am

Thank you for answering.
Below is the code I've updated. But now it is stated as

Using library LCD_I2C_lib-master in folder: C:\Users\Lenovo\Documents\Arduino\libraries\LCD_I2C_lib-master (legacy)
Using library Adafruit_Unified_Sensor at version 1.0.2 in folder: C:\Users\Lenovo\Documents\Arduino\libraries\Adafruit_Unified_Sensor 
Using library DHT_sensor_library-1.3.0 at version 1.3.0 in folder: C:\Users\Lenovo\Documents\Arduino\libraries\DHT_sensor_library-1.3.0 
Using library LiquidCrystal at version 1.0.7 in folder: C:\Program Files (x86)\Arduino\libraries\LiquidCrystal 
Using library Wire at version 1.0 in folder: C:\Program Files (x86)\Arduino\hardware\arduino\avr\libraries\Wire 
exit status 1
'degree' was not declared in this scope

#include <Streaming.h>

#include <Adafruit_Sensor.h>

#include <DHT.h>
#include <DHT_U.h>

#include <LiquidCrystal.h>

// Pin connected to the sensor data pin
#define DHTPIN 7

// Display pins
LiquidCrystal LCD (12, 11, 5, 4, 3, 2);



// Use the line according to the sensor model
// #define DHTTYPE DHT11 // Sensor DHT11
#define DHTTYPE DHT22 //DHT Sensor 22 (AM2302)
// #define DHTTYPE DHT21 // DHT Sensor 21 (AM2301)

// Definitions sensor: pin, type
DHT DHT (DHTPIN, DHTTYPE);

// Array symbol degree
byte level [8] = {B00001100,
 B00010010,
 B00010010,
 B00001100,
 B00000000,
 B00000000,
 B00000000,
 B00000000,
 };

void setup ()
{
 // Initialize the display
 LCD.begin (16, 2);
 LCD.clear ();
 // Create the custom character with the symbol of the degree
 LCD.createChar (0, degree);
 // Information on the initial display
 LCD.setCursor (0, 0);
 LCD.print ("Temp. : ");
 LCD.setCursor (13.0);
 // Shows the symbol of the degree
 LCD.write (byte (0));
 LCD.print ("C");
 LCD.setCursor (0.1);
 LCD.print ("Humid. : ");
 LCD.setCursor (14.1);
 LCD.print ("%");

 Serial.begin (9600);
 Serial.println ("Waiting for data ...");
 // Starts DHT sensor
 dht.begin ();
}

void loop ()
{
 // Wait 2 seconds between the measurements
 delay (2000);

 // Moisture reading
 h = dht.readHumidity float ();
 // Reading of temperature (Celsius)
 t = dht.readTemperature float ();

 // Check if the sensor is responding
 if (isnan (h) || isnan (t))
 {
 Serial.println ("Failed to read DHT sensor data !!!");
 return;
 }

 // Display the temperature in the serial monitor and display
 Serial.print ("Temperature: ");
 Serial.print (t);
 LCD.setCursor (8.0);
 LCD.print (t);
 Serial.print (" C * ");
 // Show the moisture in the serial monitor and display
 Serial.print ("humidity: ");
 Serial.print (h);
 Serial.println (" %");
 LCD.setCursor (8.1);
 LCD.print (h);
}

pert · October 5, 2018, 10:19am

Here you put the data for your custom degree character in an array named "level":

boice77:

// Array symbol degree

byte level [8] = {B00001100,
B00010010,
B00010010,
B00001100,
B00000000,
B00000000,
B00000000,
B00000000,
};

Here you try to create the custom character using an undeclared object named "degree":

boice77:

 // Create the custom character with the symbol of the degree

LCD.createChar (0, degree);

It looks like you did a copy/paste but forgot to change the name of the array.

boice77 · October 5, 2018, 12:21pm

Another error also found:

exit status 1
no matching function for call to 'LiquidCrystal::setCursor(double)'

Below is the code which I have changed as stated in the comments:

#include <Streaming.h>

#include <Adafruit_Sensor.h>

#include <DHT.h>
#include <DHT_U.h>

#include <LiquidCrystal.h>

// Pin connected to the sensor data pin
#define DHTPIN 7

// Display pins
LiquidCrystal LCD (12, 11, 5, 4, 3, 2);



// Use the line according to the sensor model
// #define DHTTYPE DHT11 // Sensor DHT11
#define DHTTYPE DHT22 //DHT Sensor 22 (AM2302)
// #define DHTTYPE DHT21 // DHT Sensor 21 (AM2301)

// Definitions sensor: pin, type
DHT DHT (DHTPIN, DHTTYPE);

// Array symbol level
byte level [8] = {B00001100,
 B00010010,
 B00010010,
 B00001100,
 B00000000,
 B00000000,
 B00000000,
 B00000000,
 };

void setup ()
{
 // Initialize the display
 LCD.begin (16, 2);
 LCD.clear ();
 // Create the custom character with the symbol of the level
 LCD.createChar (0, level);
 // Information on the initial display
 LCD.setCursor (0, 0);
 LCD.print ("Temp. : ");
 LCD.setCursor (13.0);
 // Shows the symbol of the level
 LCD.write (byte (0));
 LCD.print ("C");
 LCD.setCursor (0.1);
 LCD.print ("Humid. : ");
 LCD.setCursor (14.1);
 LCD.print ("%");

 Serial.begin (9600);
 Serial.println ("Waiting for data ...");
 // Starts DHT sensor
 dht.begin ();
}

void loop ()
{
 // Wait 2 seconds between the measurements
 delay (2000);

 // Moisture reading
 h = dht.readHumidity float ();
 // Reading of temperature (Celsius)
 t = dht.readTemperature float ();

 // Check if the sensor is responding
 if (isnan (h) || isnan (t))
 {
 Serial.println ("Failed to read DHT sensor data !!!");
 return;
 }

 // Display the temperature in the serial monitor and display
 Serial.print ("Temperature: ");
 Serial.print (t);
 LCD.setCursor (8.0);
 LCD.print (t);
 Serial.print (" C * ");
 // Show the moisture in the serial monitor and display
 Serial.print ("humidity: ");
 Serial.print (h);
 Serial.println (" %");
 LCD.setCursor (8.1);
 LCD.print (h);
}

system · October 5, 2018, 12:22pm

setCursor(double)why would you want to set the cursor to a fractional position?

boice77 · October 5, 2018, 12:35pm

I took this code from the internet because I'm still kind of new to arduino and the first time using this kind of code.
I'm trying to get a code with the LCD screen connected with the DHT22 but when i searched the internet what i found was mostly about the LCD screen or DHT22 only not for activating both.
Below is the attachment of the schematic reference i used for my project.

UKHeliBob · October 5, 2018, 4:15pm

no matching function for call to 'LiquidCrystal::setCursor(double)'

setCursor() takes 2 arguments not one. It needs both the row and the column

Did you perhaps confuse the full stop, which you used, with the comma which you should use ?

crazybite · October 5, 2018, 5:09pm

boice77:
I took this code from the internet because I'm still kind of new to arduino and the first time using this kind of code.
I'm trying to get a code with the LCD screen connected with the DHT22 but when i searched the internet what i found was mostly about the LCD screen or DHT22 only not for activating both.
Below is the attachment of the schematic reference i used for my project.

This is a normal occuring thing. You take some code from the internet and expect it to do your bidding after some alteration and modification. Usually not the case.

If this is your first script to me it seems complex without having done other simpler things before.

Like you I'm also new to arduino so I can't help you much yet but I think you should at least read and understand some of the examples in the IDE that will help you along way forward.

boice77 · October 6, 2018, 1:13pm

UKHeliBob:
setCursor() takes 2 arguments not one. It needs both the row and the column

What do you mean by needing row and column?

system · October 6, 2018, 1:24pm

An LCD has a number of rows (typically one, two or four) and a number of columns (eight, sixteen or twenty) where characters can be placed.

boice77 · October 24, 2018, 2:36am

I want to display the humidity and temperature in the LCD 16x2

Showing:

Humid.:12.34%
Temp.:12.34°C

How should I add the code?
I tried to look at the example code but still confused with it.

system · October 24, 2018, 8:37am

How should I add the code?

That should be pretty obvious. Fire up the IDE. Open your sketch, and start typing.

I tried to look at the example code but still confused with it.

I find that hard to comprehend. lcd.print() is dirt simple to use. You just need something to print. That could be a temperature value, a humidity value, or a literal string. None of them are difficult to come by.

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