(r4) Switches < IoT_Course

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---+ Exercise 3: Switches
---++ Introduction

Switches exist in various incarnations. There are the simple mechanical switches: on/off or push button switches but there are also switches than turn on or off with various external conditions:
   * temperature
   * infra red radiation (e.g. the Passive Infrared Sensor or PIR sensor)
   * Hall switches detecting magnetic field
   * microphone switches which turn on when a certain noise level is detected
In this exercise we will use a mechanical push button switch

<img alt="button.png" height="455" src="%ATTACHURL%/button.png" title="button.png" width="432" />

and a PIR sensor.

<img alt="pir.png" height="457" src="%ATTACHURL%/pir.png" title="pir.png" width="429" />
---++ Exercise 1:

The push button switch is connected to GPIO 17 on the ESP32 board.

Write a script that polls the state of the switch every 100 ms and prints state changes (only print out a message when the switch state has changed). Catch &lt;ctrl&gt; C to smoothly exit the program.

Check [[https://docs.micropython.org/en/latest/esp8266/tutorial/pins.html][https://docs.micropython.org/en/latest/esp8266/tutorial/pins.html ]]and [[https://docs.micropython.org/en/latest/esp32/quickref.html][https://docs.micropython.org/en/latest/esp32/quickref.html ]]for information on how to accomplish this.
---++ Exercise 2:

Do the same thing as in exercise 1 but use external interrupts and a callback routine to do the job.
---++ Exercise 3:

Combine this exercise with the exercise on !LEDs: Switch the builtin LED on when the button is pressed and off when it is released
---++ Exercise 4:

Write a program scanning the PIR sensor, indicating if a person is close. The PIR sensor, just like the push button, uses a single GPIO line as input. The boards allows to choose which GPIO to use and I selected D4 = GPIO 16
---++ Exercise 5:

The sensor kit in the lab contains a big number of sensors acting like switches:
   * rolling ball switch
   * mercury switch
   * noise level detector (microphone)
   * hall sensor (detecting magnetic field)
   * reed relay (detecting magnetic field)
   * and many more...
Connect these sensors to the ESP32 and try them with the programs developed in exercise 1-3

-- %USERSIG{UliRaich - 2020-05-06}%

---++ Comments

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I	Attachment	History	Action	Size	Date	Who	Comment
png	button.png	r1	manage	279.6 K	2020-05-06 - 09:01	UliRaich
png	pir.png	r1	manage	319.4 K	2020-05-06 - 09:01	UliRaich
Topic revision: r4 - 2020-05-21 - UliRaich