Temperature control using a DHT11

Question

I am trying to do a project on temperature control and found an example but cannot get the code to work. I have read forums and tried to fix the issue which is below the code.

Code:

#include<DHT.h> // Including library for dht
#include<LiquidCrystal.h>
LiquidCrystal lcd(2, 3, 4, 5, 6, 7);
#define dht11dpin 12
DHT11;
#define pwm 9
#byte degree[8] =
{
 0b00011,
 0b00011,
 0b00000,
 0b00000,
 0b00000,
 0b00000,
 0b00000,
 0b00000
};
#void setup()
{
 lcd.begin(16, 2);
 lcd.createChar(1, degree);
 lcd.clear();
 lcd.print(" Fan Speed ");
 lcd.setCursor(0, 1);
 lcd.print(" Controlling ");
 delay(2000);
 analogWrite(pwm, 255);
 lcd.clear();
 lcd.print("Circuit Digest ");
 delay(2000);
}
void loop()
 DHT11.read(DHT11pin);
 int temp = DHT11.temperature;
 lcd.setCursor(0, 0);
 lcd.print("Temperature:");
 lcd.print(temp); // Printing temperature on LCD
 lcd.write(1);
 lcd.print("C");
 lcd.setCursor(0, 1);
 if (temp < 26 )
 {
 analogWrite(9, 0);
 lcd.print("Fan OFF ");
 delay(100);
 }
 else if (temp == 26)
 {
 analogWrite(pwm, 51);
 lcd.print("Fan Speed: 20% ");
 delay(100);
 }
 else if (temp == 27)
 {
 analogWrite(pwm, 102);
 lcd.print("Fan Speed: 40% ");
 delay(100);
 }
 else if (temp == 28)
 {
 analogWrite(pwm, 153);
 lcd.print("Fan Speed: 60% ");
 delay(100);
 }
 else if (temp == 29)
 {
 analogWrite(pwm, 204);
 lcd.print("Fan Speed: 80% ");
 delay(100);
 }
 else if (temp > 29)
 {
 analogWrite(pwm, 255);
 lcd.print("Fan Speed: 100% ");
 delay(100);
 }
 delay(3000);
}

Error:

In file included from C:\Users\neilb\Documents\Arduino\sketch_jan20b\sketch_jan20b.ino:2:0:
C:\Users\neilb\Documents\Arduino\libraries\DHT_sensor_library/DHT.h:32:15: error: expected unqualified-id before numeric constant
 #define DHT11 11
 ^
C:\Users\neilb\Documents\Arduino\sketch_jan20b\sketch_jan20b.ino:6:1: note: in expansion of macro 'DHT11'
 DHT11;
 ^
C:\Users\neilb\Documents\Arduino\libraries\DHT_sensor_library/DHT.h:32:15: error: expected initializer before numeric constant
 #define DHT11 11
 ^
C:\Users\neilb\Documents\Arduino\sketch_jan20b\sketch_jan20b.ino:35:1: note: in expansion of macro 'DHT11'
 DHT11.read(DHT11pin);
 ^
sketch_jan20b:36: error: request for member 'temperature' in '11', which is of non-class type 'int'
 int temp=DHT11.temperature;
 ^
sketch_jan20b:37: error: 'lcd' does not name a type
 lcd.setCursor(0,0);
 ^
sketch_jan20b:38: error: 'lcd' does not name a type
 lcd.print("Temperature:");
 ^
sketch_jan20b:39: error: 'lcd' does not name a type
 lcd.print(temp); // Printing temperature on LCD
 ^
sketch_jan20b:40: error: 'lcd' does not name a type
 lcd.write(1);
 ^
sketch_jan20b:41: error: 'lcd' does not name a type
 lcd.print("C");
 ^
sketch_jan20b:42: error: 'lcd' does not name a type
 lcd.setCursor(0,1);
 ^
sketch_jan20b:43: error: expected unqualified-id before 'if'
 if(temp <26 )
 ^
sketch_jan20b:50: error: expected unqualified-id before 'else'
 else if(temp==26)
 ^
sketch_jan20b:57: error: expected unqualified-id before 'else'
 else if(temp==27)
 ^
sketch_jan20b:64: error: expected unqualified-id before 'else'
 else if(temp==28)
 ^
sketch_jan20b:71: error: expected unqualified-id before 'else'
 else if(temp==29)
 ^
sketch_jan20b:77: error: expected unqualified-id before 'else'
 else if(temp>29)
 ^
sketch_jan20b:83: error: expected constructor, destructor, or type conversion before '(' token
 delay(3000);
 ^
sketch_jan20b:84: error: expected declaration before '}' token
 }
 ^
exit status 1
request for member 'temperature' in '11', which is of non-class type 

• Maximilian Gerhardt: Are you mixing 2 libraries? Code seems like playground.arduino.cc/Main/DHT11Lib but you seem ot be using the Adafruit library github.com/adafruit/DHT-sensor-library/blob/master/examples/… ? Can you tell us whhich library installed test with above example instead? Also why are there # in #byte degree[8] and #void setup()?

Answer 1

It's a bit hard to see, but

DHT11; 

does not look like a correct statement, assuming DHT11 is a class (not a define like shown) it should be something like

DHT11 dht; 

where dht is an instance and you can use that.

Than in

DHT11.read(DHT11pin);

you should replace it by

dht.read(DHT11pin);

• neil brody: so got past that bit but getting issue with the line lcd.createChar(1, degree); saying degree was not declared in sope
• Michel Keijzers: degree should be a variable, which you haven't declared (unless it's global and you didn't post it).
• jose can u c: Several variable declarations and the setup definition are prefixed by #. Those will prevent the line from being processed correctly. degree is one of those with that error.
• Michel Keijzers: It seems the code has been changed since my comment.