Temperature Sensor with buzzer

Using Arduino Programming Questions
1

This is the code i use

float temp;
float tempC = 0;
float tempF = 0;
int buzzer = 7;
void setup()
{
pinMode(A0, INPUT);
pinMode(buzzer, OUTPUT);
Serial.begin(9600);
}
void loop()
{
temp = analogRead(A0);
temp =((temp*5)/1024);
tempC = (temp-0.5)100;
tempF = ((tempC9)/5 + 32);
Serial.print("Temperature = ");
Serial.print(tempC);
Serial.print(" C , ");
Serial.print(tempF);
Serial.println(" F ");
if (temp <=22)
{
noTone(buzzer);
delay(1000);
}
if (temp >= 18 && temp <= 22)
{
noTone(buzzer);
delay(1000);
}
if (temp > 23)
{
tone(7, 1000);
delay(200);
}
}

I can simulate it with no errors but i have a problem
if the temperature is greather than 23 there no sound coming from buzzer how to solve it?

tmp.png
tmp.png1366×768 127 KB

tmp circuit.png
tmp circuit.png1366×768 110 KB

tmp.png
tmp.png1366×768 127 KB

tmp circuit.png
tmp circuit.png1366×768 110 KB

2

You're displaying tempC and tempF, but your buzzer code relies on temp. An issue there I suspect.

3

I think you need to change temp inside if to tempC

4

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.

Thanks.. Tom... :slight_smile:

5

As was written you are comparing apples (floats) to oranges (integers) is what you do

[color=#222222] if (temp > 23)[/color][color=#222222][/color]
[color=#222222]  {[/color][color=#222222][/color]
[color=#222222]    tone(7, 1000);[/color][color=#222222][/color]
[color=#222222]    delay(200);[/color][color=#222222][/color]
[color=#222222]  }

Is what I'd do

if (tempC > 23.0f)
  {tone(7, 1000);
   delay(200);}

See the difference? You are using the raw AD value (temp), I am using the calculated C value.

Also when using floats and you use a literal to compare a float value against, I found it is best to fully describe your literal.

23 describes a literal integer, 23.0f describes a float literal. A 23 integer is not really equal to a 23.0f float as some resolution is lost in the implicit conversion.

6

This can produce an incorrect result:

 tempC = (temp-0.5)*100;

This will reduce the chance of an incorrect result.

tempC = (temp-0.5f)*100.0f;
7

wildbill:
You're displaying tempC and tempF, but your buzzer code relies on temp. An issue there I suspect.

thank you sir for clarifying this

And thank you for your all replies i manage to fix it , it finally make sound .
I really appreciate all your replies
Thank you very much