13. Radio Hot or Cold

13.1. Beacons

Set up the group value in: radio.config(group=8).

Set the radio power so that it is not quite powerful enough to reach the whole room.

radio.config(power=3)

from microbit import *
import radio


# Set radio group
radio.config(group=8)
# Set transmit power
radio.config(power=3)
radio.on()

while True:
    # Send the number 3 as a string
    radio.send("3")
    # Show the heart icon
    display.show(Image.HEART)
    # Pause for a moment
    sleep(1000)
    # Show the small heart icon
    display.show(Image.HEART_SMALL)
    # Pause for a moment
    sleep(1000)

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Exercise

1. Modify the power level to 1 or 2 to limit the distance of the beacons.

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13.2. Seekers

The seekers look for beacons and display the power reading.

0 is the strongest value which indicates zero distance from the beacon.

Typically, the strongest value read in testing has been -17, not 0.

-255 is the weakest, which indicates a long distance from the beacon.

from microbit import *
import radio


# Set radio group
radio.config(group=8)
radio.on()

# Function to handle received messages
def on_received_message():
    incoming_full_details = radio.receive_full()
    if incoming_full_details:
        msg, rssi, timestamp = incoming_full_details
        # Show the signal strength
        display.scroll(rssi, delay=60)

while True:
    # received
    on_received_message()
    sleep(200)

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13.3. Hot and cold meter

Set up the group value in: radio.config(group=8).

Set the radio power so that it is at the maximum power.

radio.config(power=7)

from microbit import *
import radio


# Set radio group
radio.config(group=8)
# Set transmit power
radio.config(power=7)
radio.on()

while True:
    # Send the number 7 as a string
    radio.send("7")
    # Show the heart icon
    display.show(Image.HEART)
    # Pause for a moment
    sleep(1000)
    # Show the small heart icon
    display.show(Image.HEART_SMALL)
    # Pause for a moment
    sleep(1000)

Here is some code for a 5 level meter.

Can you modify the the code to show 10 levels by using brightness of 4 and 9?

from microbit import *
import radio


radio.config(group=8)
radio.on()


def display_level(level):
    x_list = [0, 1, 2, 3, 4]
    # display
    if level < 2:
        y_val = 4
        y_list = None
        y_clear_list = [0, 1, 2, 3]
    elif level < 4:
        y_val = 3
        y_list = [4]
        y_clear_list = [0, 1, 2]
    elif level < 6:
        y_val = 2
        y_list = [3, 4]
        y_clear_list = [0, 1]
    elif level < 8:
        y_val = 1
        y_list = [2, 3, 4]
        y_clear_list = [0]
    elif level < 10:
        y_val = 0
        y_list = [1, 2, 3, 4]
        y_clear_list = None
    else:
        y_val = None
        y_list = [0, 1, 2, 3, 4]
        y_clear_list = None

    for x in x_list:
        if y_val is not None:
            display.set_pixel(x, y_val, val)
        if y_list is not None:
            for y in y_list:
                display.set_pixel(x, y, 9)
        if y_clear_list is not None:
            for y in y_clear_list:
                display.set_pixel(x, y, 0)


while True:
    message = radio.receive_full()
    if message:
        signal = int(message[1])
        # scale signal strength to levels 0 to 9
        # the values here may need adjusting(-116, -17)
        level = scale(signal, from_=(-116, -17), to=(0, 9))
        display_level(level)