IoT Sensor Hello World

What you will learn in this tutorial:

Hardware setup to capture the state of the push button
Setup button callback in Iottly
Edge computing in Iottly

Preconditions

After connecting your Raspberry Pi:

Connect Raspberry Pi to Iottly

you can follow this tutorial.

Hardware setup

In this exercise we are going to use pin #12 as an input (sensor) to capture the state of the push button

Create a circuit like the one in the sketch
This time the yellow wire connect Pin #12 to 3.3V (through the push button)

Raspberry Pi 1 Rev 1 Pinout reference here

Raspberry Pi 1 Rev 2 Pinout reference here

Raspberry Pi 2/3 Pinout reference here

Raspberry Pi zero w Pinout reference here

Let’s use Iottly to configure an event to be triggered when the button is pressed

Setup button callback in Iottly

In the “Management Scripts” panel edit the following snippets:

init :
- Initialize Pin #12 to be managed as input
  - The GPIO.PUD_DOWN flag allows to set a software version of a pull down resistor
- add_event_detect allows to register a callback to be executed whenever the input changes its status
  - The GPIO.BOTH means the event must be triggered both on rising or on falling signal
  - The bouncetime avoids multiple events to be triggered due to physical bouncing of the switch

def init():
  #...

  #-------------------------------
  # here your code!!

  pin = "7"
  GPIO.setup(int(pin), GPIO.OUT)  
  pin = "12"
  GPIO.setup(int(pin), GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
  GPIO.add_event_detect(int(pin), GPIO.RISING, callback=button_pressed, bouncetime=200)

  #---------------------------------

global:
- Add the callback function button_pressed

# ...
def button_pressed(channel):
  status = GPIO.input(7)
  send_msg({"button_pressed": {"GPIO": channel, "state": status}})

It will send a message to Iottly evry time the button is pressed
Test the “IoT Sensor Hello World” from the Console

Edge computing in Iottly

Let’s add an edge feedback so that when the button is pressed, the green LED is switched on.

Once flashed over-the-air this feedback will be triggered by the Raspberry PI, even if it is disconnected from the Internet.

global:
- modify the callback function button_pressed
- The green LED is controlled by pin #7

# ...
def button_pressed(channel):
  status = GPIO.input(7)

  # -------- edge feedback -------------
  status = not status
  GPIO.output(7,status)
  # -------- edge feedback -------------

  send_msg({"button_pressed": {"GPIO": channel, "state": status}})