Raspberry Pi Control

This project is to control various hardware on a Raspberry Pi from a remote web page. Hardware includes:

• A 4 relay header board to control a lamp and solenoid
• LCD Display LCD1602
• PWM Devices hub can control up to 16 servos including continuous and angular servos

Device Setup

• Stack 4 relay board on top of Raspberry pi
• Servo 1: Attach Black to pin 9, Red to pin 1 and White/Yellow to pin 12 NB: Depending on your servos you may have to connect these to 5V instead
• LEDS: Attach to pins 11, 13, 36
• Switch input: Attach to pin 15
• LCD 1602 with I2C interface. GND Pin 39, 5V Pin 2, SDA Pin 3, SCL Pin 5 such as this one: https://www.amazon.co.uk/gp/product/B07J2Q9LB7/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
• Connect Pi and relay board to 5V 3A supply
• Mounting components on Din rail is optional but just helps to make things tidier
• In Azure. Create Iot Hub in standard tier and go to the following blades:
  • Shared access policy. For DEVICE and put in IoTHubConnectionString
  • IoT Devices. Add your Raspberry Pi, give device name e.g. RaspberryPi4
  • Networking. Don't put in IP restrictions if you want your azure function to be able to contact the IoT Hub
• and reboot the device
• Publish the code to a directory called Control on the device
• Log into the Raspberry Pi and in a command prompt:
  • cd Control
  • chown pi ./Control
  • chmod +rwx ./Control
• In order to get the program to run when the Pi is started, do the following:
  • sudo nano /etc/rc.local
  • Just before the Exit command at the end, put in bash /home/pi/Control/Control &
  • Press Ctrl + S then Ctrl + X
  • restart the raspberry pi

Blazor App Setup

• In Azure.
  • Create blob storage and copy the connection string

appsettings.json

• ApplicationUserName / ApplicationPassword - Make up a username/password combination
• BlobContainerName - e.g. pieventhub
• BlobStorageConnectionString - The connection string from above Azure
• DeviceId - device name as configured above e.g. RaspberryPi4
• EventHubConnectionString - Taken from IoTHub -> built in endpoints -> Event hub-compatible endpoint
• EventHubName - Taken from IoTHub -> built in endpoints -> Event hub-compatible name
• IoTHubConnectionString - Take from device, shared access policy

Operation

You can use the IoT Hub explorer to send direct messages to the Raspberry Pi and control its hardware using the 'ControlAction' direct method and following json package: { "Method": SetRelay, GetRelay, SetServo, SetText, SetOutput, GetInput, SetPwm "Number": Value of the hardware if applicable. -1 to 15 for Pwm "Value": 0 or 1 for relays and 0 to 1 for servos and pwm "Message": When writing to the screen, the message to send }

e.g. this will turn Relay 4 on: { "Method": "SetRelay", "Number": 4, "Value": 1, "Message": "" }

this writes a message to the second row (Number) and third character location of the LCD screen:

{ "Method": "SetText", "Number": 2, "Value": 3, "Message": "Hardware Test" }

if there is a mistake then a bad request will be returned to you

Setting via desvice twin

You can set the state of LED 1 by changing the desired property:

{ "properties": { "desired": { "ledState": 0, ...

Tech notes

Publish as single file does not seem to work, you get a file not found error

You may have to follow the instructions here to run without sudo: https://raspberrypi.stackexchange.com/questions/40105/access-gpio-pins-without-root-no-access-to-dev-mem-try-running-as-root sudo apt-get update sudo apt-get upgrade sudo chown root.gpio /dev/gpiomem sudo chmod g+rw /dev/gpiomem

A rapsberry pi can control a maximum of two servos using its PWM channels according to this reference: https://embeddedcircuits.com/raspberry-pi/tutorial/how-to-generate-pwm-signal-from-raspberry-pi