Radio alarm za vrata

1. korak: Napravi

Što je to?

Bežični alarm koji će te upozoriti da netko otvara vrata - ili ih je ostavio otvorenima.

How to make it

• You will need two micro:bits with different code on each. One micro:bit acts as a radio transmitter and the other as a radio receiver.
• Attach the transmitter micro:bit and battery pack to the corner of a door frame and attach a magnet close to it on the corner of a door.
• Place the receiver micro:bit anywhere nearby.
• If the alarm doesn’t work as you expected, you may need to change the magnetic force strength number in the transmitter code. Pressing button A shows the current magnetic force reading. Use this to decide on the threshold number, taking readings with the door open and closed.

Kako to radi

• The transmitter program uses the micro:bit’s compass (magnetometer) input sensor and a loop to measure the strength of the magnetic field every two seconds.
• It uses selection so when the magnetic field strength falls below a certain level (the threshold), it sends a radio signal ‘open’. If the magnetism reading goes above the threshold, it sends the signal ‘closed'.
• When the receiver micro:bit receives the signal ‘open’, a cross appears on its LED display and an audible alarm sounds. When it receives the signal ‘closed’, a tick appears on its LED display and no sound plays.

Što ti treba

• two micro:bits and at least one battery pack
• magnet
• some adhesive putty to fix a magnet to a door and a micro:bit to a door frame
• if you have a V1 micro:bit and want to hear an audible alarm, optional headphones, buzzer or speaker and crocodile clip leads to attach them

2. korak: Kodiraj

Senzor/ predajnik:

1from microbit import *
2import radio
3radio.config(group=17)
4radio.on()
5
6while True:
7    if button_a.was_pressed():
8        display.scroll(compass.get_field_strength())
9    if compass.get_field_strength() < 100000:
10        display.show(Image.DIAMOND_SMALL)
11        radio.send('open')
12    else:
13        display.clear()
14        radio.send('closed')
15    sleep(2000)
16

Alarm / prijemnik:

1from microbit import *
2import music
3import radio
4radio.config(group=17)
5radio.on()
6
7while True:
8    message = radio.receive()
9    if message:
10        if message == 'open':
11            display.show(Image.NO)
12            music.play(["C4:4"])
13        if message == 'closed':
14            display.show(Image.YES)
15

3. korak: Unaprijedi

• Upotrijebi nekoliko micro:bitova za praćenje više vrata i slanje raznih poruka, primjerice, 'stražnja vrata su otvorena'.
• Upotrijebi varijablu kojom ćeš mjeriti koliko dugo su vrata otvorena – bi li to koristilo za štednju energije za grijanje?