Raspberry Pi Class Ed 299. Mike Davis Truman College 5/26/2015

Transcription

1 Raspberry Pi Class Ed 299 Mike Davis Truman College 5/26/2015

2 Goals for Today Discuss Raspberry Camera Projects Fruit Rotting Air Powered Car Photo booth Use a Python Program to control the camera Copy, edit, and execute Python programs Connect a temperature sensor Make a program repeatable in Cron Make a local web server Upload the temperatures to Google

3 Start of Class Plug in the Raspberry Pi. Get the IP address (ifconfig). Log in via PuTTY from another computer.

4 Bash Commands BASH Bourne Again Shell Based on a shell that interprets commands. Commands that are typed directly into the command terminal. Considered easy to use for beginners, and powerful for advanced users. Create a File sudo nano hello.sh #! /bin/bash echo Hello World Save it sudo chmod +x hello.sh./hello.sh

5 Bash Commands & Cron Useful Anything you would want to do from the command line can be made into a Bash script. Make the script executable sudo chmod +x name.sh Execute it./name.sh

6 Get a Python Program Go to: Find the time lapse program about 2/3 of the way down the page. Highlight and copy it. Open a file called camera.py (sudo nano camera.py) Paste it by right clicking Close and save it. Execute it (sudo python camera.py)

7 Some things to know in Python Python is a programming language. Pre-installed on the Raspberry Pi. Has numerous libraries that can be imported (such as picamera). A # at the start of the line will be ignored (commented out). Python programs are pretty readable and can be figured out without a lot of effort.

8 Structure of a Cron Job * * * * * command Min (0-59) Hour (1-24) Day(1-31) Month (1-12) Day of the Week (1-7) Run the Python program starting at 6:00 every day * * * python /home/pi/camera/camera.py Run the Python program starting 6:00 every Monday * * 1 python /home/pi/camera/camera.py Run the Python program whenever your start the python /home/pi/camera/camera.py

9 Project 2 Make a Local Web Server Description Apache is a popular web server application that can be used to serve up web pages on a local network. It can serve up HTML pages over HTTP. With additional modules you can serve up dynamic web pages. Goals Download / install Apache Navigate to your local web page Navigate to another web page Make changes to your web page

10 How to Make it a Web Server. Instructions Command sudo apt-get update sudo apt-get upgrade {NOT NOW} Command Sudo apt-get install apache2 -y Effect This will look for updates to your operating system and install them. Do before starting almost any project. If you don t do it often, it will take a while. This will download and install the Apache application on your Raspberry Pi. You must be connected to the internet for this work. Take couple minutes.

11 Lets find your Web Page Commands Make sure you know the IP address for your RPi. sudo ifconfig In your web browser go to: From any computer on the same network, go to: Your Web Page

12 Make a Change to Your Local Web Page Commands You have a default web page already loaded. In the terminal type cd /var/www/ sudo nano index.html Save changes. Refresh the web page. What you are doing You navigating to a specific file folder and using a text editing program nano to open the index.html file.

13 Project 3 Set up a Temperature Sensor What we will need to do Build the temperature sensing circuit. Test the circuit. Copy a python program. Goals Make a temperature sensing circuit. Load and execute a python program. Read temperatures in Celsius.

14 Make the Circuit Raspberry Pi GPIO Pins Circuit Diagram

15 Connections to the Raspberry Pi The Circuit Diagram From the Raspberry Pi Connect Red to Pin 1 and the right prong of the probe. (Power) Yellow to Pin 7 and the center prong of the probe. (Data) Black to Pin 6 and the left prong on the probe. (Ground)

16 Software Configuration Commands In the terminal type: sudo nano /boot/config.txt Go to the bottom and insert dtoverlay=w1-gpio Save, close, and reboot. sudo reboot Why? I don t know. This is a one time operation that will activate one-wire devices like the temperature probe. Do this once, and you don t have to do it again.

17 Software Configuration Commands In the terminal, type: sudo modprobe w1-gpio sudo modprobe w1-therm Type cd /sys/bus/w1/devices ls cd 28* cat w1_slave What does this do? This activates the pins for readings. This goes to the folder where that device is located. Once we find it, we will get it read a temperature.

18 You Should See This

19 A python program to record temperatures Use a python program to record lots of temperatures in a Google Spreadsheet. Will require a Google account May require a change in your security settings Need to load the gspread python library git clone gspread cd gspread sudo python setup.py install sudo reboot

20 Create A Google Spreadsheet Go to Drive.Google.Com Create a New Spreadsheet and note the name: Ex. temperature (case sensitive) Download Remove Blank Rows This will put an add-on in your Google Spreadsheets. Label A1 as time and B1 as temp. Remove the blank rows.

21 A python program to record temperatures Download a python program from GitHub. sudo git clone cd temperature sudo nano temp.py In that program put in your Google information gc = gspread.login('account@account.com','password') worksheet = gc.open('spreadsheet_name').sheet1 Save and close program <Cntrl x>. In the terminal type: sudo python temp.py

22 Make it repeatable in Cron This sets up operations that are scheduled to repeat at regular intervals or at regular times. In the terminal type: sudo crontab e In this program, add this line at the /bin/sleep 10 ; python /home/pi/temperature/temp.py & */1 * * * * python /home/pi/subdirectory/temp.py Close the program <Cntrl x> Reboot: sudo reboot Watch your Google Spreadsheet

23 Resources Sign Up For Element14 STEM Academy Where to Get Help / Ideas RaspberryPi.org Raspberry Pi Forum Element14 STEM Academy Make Magazine Adafruit RaspiTV