3. Thermometer

3.1. Temperature Function

The thermometer gets the temperature as an integer in degrees Celsius.

temperature()

Return the temperature of the microbit in degrees Celsius.

The temp variable below is an integer. It has to be first converted to a string to join it with the unit symbol, C.

from microbit import *

while True:
    temp = temperature()
    display.scroll(str(temp) + 'C')
    sleep(500)

The temperature the thermometer measures will typically be higher than the true temperature due to heat from the nearby electronics on the microbit.

Exercises

  • Plug in the battery pack and move the microbit to a warmer or cooler place. What temperatures do you get?

  • Compare the temperature inside with that outside.

  • Place the microbit on a paper towel in the freezer or fridge for 2 min and read the temperature.

Tasks

  • Use an if block so that one image is shown when it is below 20 degrees and another image is shown when it is above 20 degrees.

  • Use the A-button to store the temperature in the variable tempA. Use the B-button to store the temperature in the variable tempB. Calculate the difference between them using tempA - tempB and scroll this difference.

Use an if block so that one image is shown when it is below 25 degrees and another image is shown when it is 20 degrees or higher.

from microbit import *

while True:
    temp = temperature()
    #display.scroll(temp)
    if temp < 25:
        display.show(Image.UMBRELLA)
    else:
        display.show(Image.TSHIRT)

Use the A-button to store the temperature in the variable tempA. Use the B-button to store the temperature in the variable tempB. Calculate the difference between them using tempA - tempB and scroll this difference. To make sure that both temperature variables have a value, set them both before the while True loop.

from microbit import *

tempA = temperature()
tempB = temperature()
while True:
    temp = temperature()
    if button_a.is_pressed():
        tempA = temp
    elif button_b.is_pressed():
        tempB = temp
    display.scroll(tempA - tempB)
    sleep(200)

Project

Keep track of the lowest and highest temperatures recorded by using 3 variables: current_temp is the current temperature reading, max_temp is the maximum temperature and min_temp is the minimum temperature.
At the start, set all 3 variables to the same value and scroll that value. Then use a while-loop to take a reading every second and put it in current_temp, then update the max_temp or min_temp depending on the new reading.
If current_temp is less than (<) min_temp, update min_temp.
If the current_temp is greater than (>) max_temp, update max_temp.
Use the A-button to scroll min_temp.
Use the B-button to scroll max_temp.
Press down both A and B-buttons together to scroll the difference between the max and min temperatures.
from microbit import *

current_temp = temperature()
max_temp = current_temp
min_temp = current_temp
display.scroll(current_temp, delay=80)
while True:
    current_temp = temperature()
    if current_temp < min_temp:
        min_temp = current_temp
    elif current_temp > max_temp:
        max_temp = current_temp
    if button_a.is_pressed() and button_b.is_pressed():
        display.scroll(max_temp - min_temp, delay=80)
    elif button_a.is_pressed():
        display.scroll(min_temp, delay=80)
    elif button_b.is_pressed():
        display.scroll(max_temp, delay=80)
    sleep(1000)