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# 무선 문열림 경보기

고급 | MakeCode, Python | LED, 라디오, 자기 센서 | 라디오 파, 선택 실행, 센서, 자기력, 조건/관계 연산자, 통신

## 1단계: 만들어 보세요.

### 프로젝트 소개

무선 문열림 경보기를 이용해서 문이 열렸는지, 문이 닫혔는지 알아내 보세요.

### 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.

### 설명

• 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.

### 준비물

• two micro:bits and at least one battery pack
• 자석 1개
• 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

## 2단계: 프로그래밍 해보세요.

### 센서 / 신호 전송기:

``````1from microbit import *
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)
12    else:
13        display.clear()
15    sleep(2000)
16``````

### 경보기 / 신호 수신기:

``````1from microbit import *
2import music
6
7while True: