Celsius to Fahrenheit

Part of the Displays and Sensors section of Coddy's Arduino journey. Lesson 21 of 24.

Fahrenheit is another temperature scale: water freezes at 32 F and boils at 212 F. To convert, multiply the degrees C by 9, divide by 5 and add 32:

float fahrenheit = celsius * 9 / 5 + 32;

The order matters. The board works left to right through * and /, before +. Starting with celsius, a float, keeps every step in decimals.

Written 9 / 5 * celsius + 32, the first step divides two whole numbers: 9 / 5 is 1, the fraction is dropped, and the answer is celsius + 32. Writing 9.0 / 5 would fix it too.

Challenge

Easy

The sketch works out celsius. Print Fahrenheit instead:

convert with celsius * 9 / 5 + 32
print the Fahrenheit value instead of the Celsius one

Press Run, then Check.

Try it yourself

const float BETA = 3950;  // the thermistor's beta value

void setup() {
  Serial.begin(9600);
}

void loop() {
  int reading = analogRead(A0);
  float celsius = 1 / (log(1 / (1023.0 / reading - 1)) / BETA + 1.0 / 298.15) - 273.15;
  // turn celsius into fahrenheit and print that instead
  Serial.println(celsius);
  delay(500);
}

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Displays and Sensors

Practice on your own: Arduino playground