IoT Setpoints Hello World

What you will learn in this tutorial:

• Hardware setup to remotely control the LEDs
• Message Setup
• Iottly Code

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 pins #23 and #24 to control the intensity of two LEDs by means of the PWM protocol
• PWM (pulse width modulation): here
• Create a circuit like the one in the sketch
• The two green wires connect the LEDs’ anode to RPi Pins #23 and #24 (through two 220Ohm resistors)

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 a command to remotely control the LEDs

Message Setup

Create the following message:

• Name:
  • LED_intensity
• Description:
  • IoT Setpoints Hello World
• We need two keywords:
  • “color”: to tell the board which LED we want to control
    • Type: Multiple Value
    • Values:
      • red
      • green
  • “intensity”: to tell the board the intensity value we want to set for the LED
    • Type: FreeValue
    • Any value in [1, 100] (expressed as %)

Iottly Code

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

• globals:
  • Add a global dictionary to map colors to PWM objects
    • The COLOR_TO_PWM_MAP dictionary needs to be global since it will be accessed by both the init and the LED_intensity functions

#add at the end of globals:
COLOR_TO_PWM_MAP = {}

• init
  • Initialize Pin #23 and #24 to be managed as output
  • Create PWM objects for each pin and store them in the COLOR_TO_PWM_MAP dictionary
  • 60 is the base frequency for the modulation

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.BOTH, callback=button_pressed, bouncetime=200)

  GPIO.setup(23, GPIO.OUT)
  GPIO.setup(24, GPIO.OUT)  
  COLOR_TO_PWM_MAP.update({
    'green': GPIO.PWM(23, 60),
    'red': GPIO.PWM(24, 60),
  })    
  #-----------------------------------------------------------------------------#

• LED_intensity :
  • Keep in mind the format of the incoming message: {"LED_intensity":{"color":"<red|green>","intensity":"<freevalue>"}}

def LED_intensity(command):
  #...
  cmdpars = command["LED_intensity"]
  #...
  #-----------------------------------------------------------------------------#
  # here your code!!
  led_color = cmdpars.get('color', 'red')
  pwm = COLOR_TO_PWM_MAP.get(led_color)
  intensity = int(cmdpars.get('intensity', 100))

  pwm.start(intensity)
  #-----------------------------------------------------------------------------#

• The color keyword is used to obtain the pwm object from the COLOR_TO_PWM_MAP dictionary
• The intensity keyword is used to start a PWM with the desired duty cycle
• 
• Test the “IoT Setpoints Hello World” from the Console