arduino compile error

Bill Frick's picture

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Joined: Dec 27, 2017

Replies: 3
arduino compile error
December 27, 2017 - 7:48am

I have built my first Arduino project - the Temperature controlled fan from the code and schematic on this site. 

https://circuitdigest.com/microcontroller-projects/automatic-temperature...

 After some time I got past the library include problem to now have this:

sketch_dec26a:6: error: 'dht' does not name a type

 dht DHT;

 ^

C:\Users\wfene\OneDrive\Documents\Arduino\sketch_dec26a\sketch_dec26a.ino: In function 'void loop()':

sketch_dec26a:39: error: expected unqualified-id before '.' token

   DHT.read11(dht_dpin);

      ^

sketch_dec26a:40: error: expected primary-expression before '.' token

   int temp=DHT.temperature;

               ^

exit status 1
'dht' does not name a type

Any help to clear this hurdle would be appreciated so I can put this to work on my solar furnace !

Aswinth Raj's picture

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Joined: Aug 16, 2016

Replies: 798
Did you use the same program
December 27, 2017 - 11:35am

Did you use the same program given in that link or did you make any modifications? I tried the same program from the link and it compiled properly for me.

Its always a good practice to paste your code in the forum rather than pointing it to a link. This way people can help you a bit more better

Bill Frick's picture

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Joined: Dec 27, 2017

Replies: 3
compile error code paste
December 28, 2017 - 2:03am

Here is the code as copied directly from the sketch editor:

#include<dht.h>      // Including library for dht
#include<LiquidCrystal.h>
LiquidCrystal lcd(7, 6, 5, 4, 3, 2);

#define dht_dpin 12 
dht DHT;

#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()
{
  DHT.read11(dht_dpin);
  int temp=DHT.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);
    }void setup() {
  // put your setup code here, to run once:

}

Which results in the following error messages:

sketch_dec27a:6: error: 'dht' does not name a type

 

sketch_dec27a:6: error: 'dht' does not name a type

 dht DHT;

 ^

C:\Users\wfene\OneDrive\Documents\Arduino\sketch_dec27a\sketch_dec27a.ino: In function 'void loop()':

sketch_dec27a:39: error: expected unqualified-id before '.' token

   DHT.read11(dht_dpin);

      ^

sketch_dec27a:40: error: expected primary-expression before '.' token

   int temp=DHT.temperature;

               ^

exit status 1
'dht' does not name a type

* If I could just get past the 'dht DHT;  I'm sure the rest can be sorted out.  I wonder if the 'copy > paste' I do causes the error but the code looks just like the listing on the project page.  I have 5 of these DHT sensors and have ideas for all !  If I never get the code sorted for them they are useless !

Thanks in advance for your help.

Bill Frick's picture

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Joined: Dec 27, 2017

Replies: 3
SOLVED !
December 28, 2017 - 7:00am

After much surfing I concluded that the error was based on which 'dth lib ' one used !  One github repository actually bemoaned the fact that the syntax in the various dthlib s varied widely and because the sketch code [c++] is case sensitive beginners like me will chase errors because of this.

Bottom line I found one that had sample code syntax which I transposed to my project and got to compile !

Aswinth Raj's picture

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Joined: Aug 16, 2016

Replies: 798
Glad you got it working.. I
December 29, 2017 - 11:59am

Glad you got it working.. I compiled your program and it has no errors here. So no doubt the library was the culprit