serg-firsov / sytac-iot-slab

Sytac IoT sLab

Programming workflow

1. If you on Windows install Bonjour service from Apple. On Mac skip this step.
2. If you don't have them installed yet, install JDK 8 and Maven
3. If you are using Windows Install Putty. On Mac please use any other SSH client.
4. Flash this image to 8GB micro SD card and insert it into Raspberry Pi Zero W (to make it shorter RPi)
5. Connect RPi to your computer, open Putty and create a new session
   • Host name: rpi-1.local
   • Password: sytac-1
   • Port: 22
   • Click "Open" to connect to the RPi
6. To build the java project and upload it to RPi execute the command mvn clean package
7. To run the program on RPi in open Putty terminal execute the script /home/pi/run_app.sh
8. To close the program execute the command ps -ef | grep java to find the program process ID and than execute kill <process id>
9. When you finished programming and want the program to be ran on Linux startup add the program to crontab
   • Execute crontab -e
   • Add this to the end of the config: @reboot /home/pi/run_app.sh >> /home/pi/slab.log &
   • Execute sudo reboot now to reboot your RPi

Project overview

The project is making use of Pi4J library to access GPIO pins on the RPi, and Ubidots cloud IoT frontend to remotely operate the GPIO pins. If you build the project and run the application on RPi, the application will:

1. Try to obtain access token from Ubidots using an API key.
2. Then, from Ubidots, it will try to get the value of the variable wheel-engaged for the device weel
3. Then it will try to get the value of the variable wheel-direction for the device weel
4. Then the values of the wheel-engaged and wheel-direction variables is supplied to the method Motor.go(), which toggles GPIO pins on the RPi.

Please put your API key and the GPIO pins numbers you want to use into the application.properties file.

What to do with Ubidots

1. Create an account on ubidots.com. They offer 1 month trial without asking for your credit card, that's why Google IoT was not chosen for this workshop.
2. Create a device with the name wheel
3. Inside of the device wheel create 2 variables: wheel-direction and wheel-engaged
4. Create a dashboard
5. On the dashboard create 2 controls with the type Switch and assign previously created variables on them. You should see 2 buttons. If you click on the button it should change the last value of the assigned for it variable.

What to do in the Java project

Take your API key from Ubidots and put it into the application.properties file instead of the existing one. Build the project and run the application on RPi, the output of the program should give you something like this:

   Motor engaged: true; Direction: 1
   Motor engaged: true; Direction: 1
   Motor engaged: true; Direction: 1

This means the program is successfully fetching values of the wheel-direction and wheel-engaged variables from Ubidots. Now if you will be pushing buttons you created on Ubidots you should see the output of the program reflects it.

What to do with hardware

0. Never short out the +/- from the power supply
1. Look at the pinout of the Raspberry Pi Zero W on the Pi4J project website to find the pins on the board
2. Look at the pinout of the L298N Dual H Bridge
3. Connect ground pins of RPi and L298N together
4. Connect RPi GPIO pins you've used to IN1 and IN2 (or IN3, IN4) on the L298N board
5. Connect OUT1 and OUT2 (or OUT3 and OUT4) to the motor
6. Connect negative contact of the power supply to the ground pin of the L298N board
7. Connect positive contact of the power supply to the +12V pin of the L298N board

Tips and tricks

• To see the GPIO pins status execute gpio readall in the RPi console
• To look up the GPIO pinout of RPi Zero W you can check Pi4G library website http://pi4j.com/pins/model-zerow-rev1.html
• To scan available WiFi networks execute sudo iwlist wlan0 scan
• To set up WiFi setting via interactive interface sudo raspi-config
• To set WiFi settings via config file edit /etc/wpa_supplicant/wpa_supplicant.conf sudo nano /etc/wpa_supplicant/wpa_supplicant.conf