4. Heart beat simulation

4.1. Pin touching

To simulate being connected to a heart monitor, touching pin0 (or pin1 or pin2) and the Ground pin (GND) will be used.
Hold the GND pin with thumb and forefinger of the right hand.
V2: Touching the logo pin by itself also works. (pin_logo)

is_touched(): Return True if the pin is being touched with a finger, otherwise return False. It is best to touch the ground pin with the other hand.

The code below is for testing pin0 touching. When touched, a 0 will be shown.

from microbit import *

while True:
    if pin0.is_touched():
        display.show(0)
        sleep(500)
    else:
        display.clear()
    sleep(100)

Tasks

Add an elif branch to test for pin1 touching and display a 1 when it is.
Add another elif branch to test for pin2 touching and display a 2 when it is.

4.2. Pulse design

The image below is a design for a heart_beat.
This is the main shape found in an electrocardiogram.
To simulate a heart monitor animate this shape from right to left across the 5 by 5 grid.

Tasks

Plan the design of 7 images to simulate the above heart beat being scrolled from right to left starting with the left edge of the pulse and ending with a flat line. Attempt to complete the code for the 7 images before reading on.

The code has 7 heart beat images which are combined in a list called heart_beat.

When pin0 is touched, the sequence of images is show with 100ms between images.

from microbit import *

hb1 = Image("00009:00009:00009:99999:00000")
hb2 = Image("00090:00090:00090:99999:00009")
hb3 = Image("00900:00900:00900:99999:00090")
hb4 = Image("09000:09000:09000:99999:00900")
hb5 = Image("90000:90000:90000:99999:09000")
hb6 = Image("00000:00000:00000:99999:90000")
hb7 = Image("00000:00000:00000:99999:00000")

heart_beat = [hb1, hb2, hb3, hb4, hb5, hb6, hb7]

display.show(hb7)

while True:
    if pin0.is_touched():
        display.show(heart_beat, delay=100, wait=True)

The delay can be adjusted to match particular heart rates (in beats per minute).
Use the formula to calculate the delay: delay = 60000/(HR * 7)
For a heart rate of 65 bpm (beats per minute), the delay is 132.

Use google metronome https://g.co/kgs/Rjdr6e.

Use https://www.musicca.com/metronome as an alternative metronome.

Tasks

Set the google metronome https://g.co/kgs/Rjdr6e to 65 and see if a delay of 132 keeps in time with the metronome.
Set the google metronome https://g.co/kgs/Rjdr6e to 100. Use the formula to calculate the delay required for a HR of 100 bpm. See if this keeps in time with the metronome.

4.3. Using a function to calculate the delay for a Heart rate

Define a function, delay_for_heart_rate(hr), to return the delay needed to simulate a specified heart rate.
Give the hr parameter a default value of 60 as in def delay_for_heart_rate(hr=60) to have a default heart rate of 60 bpm.
Use the int function to convert a decimal to a whole number.
Below is the function.

def delay_for_heart_rate(hr=60):
    return int(60000/(hr * 7))

Use the working code below as the starting point for the tasks that follow.

from microbit import *

hb1 = Image("00009:00009:00009:99999:00000")
hb2 = Image("00090:00090:00090:99999:00009")
hb3 = Image("00900:00900:00900:99999:00090")
hb4 = Image("09000:09000:09000:99999:00900")
hb5 = Image("90000:90000:90000:99999:09000")
hb6 = Image("00000:00000:00000:99999:90000")
hb7 = Image("00000:00000:00000:99999:00000")

heart_beat = [hb1, hb2, hb3, hb4, hb5, hb6, hb7]


def delay_for_heart_rate(hr=60):
    return int(60000/(hr * 7))


display.show(hb7)

while True:
    if pin0.is_touched():
        hr_delay = delay_for_heart_rate(60)
        display.show(heart_beat, delay=hr_delay, wait=True)

Tasks

Add an elif branch to test for pin1 touching and use a heart rate for pin1 of 100 bpm.
Add another elif branch to test for pin2 touching and use a heart rate for pin2 of 150 bpm.