Intro to Electronics in Python

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Intro to Electronics in Python

  1. 1. Intro to Electronics in Python Anna Gerber Intro to Electronics in Python
  2. 2. Electricity •  Electricity is a form of energy •  We can connect components that convert electrical energy into other forms of energy: light, sound, movement, heat etc, into a circuit •  In a Direct Current (DC) circuit,
 electrical energy flows from 
 the positive side of a 
 power source to the
 negative side, i.e. from 
 + (power) to – (ground) Anna Gerber Intro to Electronics in Python
  3. 3. Electrical concepts •  Current (Amps): measures the flow of electrical energy through a circuit •  Voltage (Volts): measures difference in potential energy between the positive and negative sides of a circuit •  Resistance (Ohms): measures a material's opposition to the flow of energy •  Power (Watts): the rate at which energy is converted from one form to another Anna Gerber Intro to Electronics in Python
  4. 4. Ohm's Law Current = Voltage / Resistance •  Increase the voltage, and the current will increase (i.e. speed up) •  Increase the resistance and the current will decrease Anna Gerber Intro to Electronics in Python
  5. 5. Sensors •  Environmental  condi/ons       (e.g.  temperature,  humidity,  smoke)   •  Magne/c  (e.g.  hall  effect  sensor)   •  Light  (e.g.  photo  resistor)   •  Sound  (e.g.  microphone)   •  Mo/on  (e.g.  accelerometer,  /lt,  pressure)   •  User  /  Physical  Input  (e.g.  buDon)   Anna Gerber Intro to Electronics in Python
  6. 6. Actuators •  Light  &  Displays  (e.g.  LED,  LCD)   •  Sound  (e.g.  Piezo  buzzer)   •  Mo/on  (e.g.  Servo,  DC  Motor,  Solenoid)   •  Power  (e.g.  Relay)   Anna Gerber Intro to Electronics in Python
  7. 7. Digital vs Analog •  Digital –  discrete values (0 or 1)(LOW or HIGH) –  Examples: tilt sensor, push button, relay, servo •  Analog –  continuous values –  Examples: photo resistor, DC motor •  Some sensors support both digital and analog outputs Anna Gerber Intro to Electronics in Python
  8. 8. Using a Breadboard Anna Gerber Intro to Electronics in Python •  Use to prototype circuits without soldering by plugging in components and jumper wires •  Letters and numbers for reference •  Numbered rows are connected •  Some have power bus along the sides
  9. 9. Resistors •  Introduces resistance, so restricts the amount of current that can flow through a circuit •  Coloured bands indicate resistance •  Can be connected in either direction Anna Gerber Intro to Electronics in Python
  10. 10. LEDs •  Light Emitting Diode •  Polarized: diodes act like one way valves so must be connected in a certain direction •  Emits light when a current passes through Anna Gerber Intro to Electronics in Python Anode  (+)     longer  lead   connects  to  power   Cathode  (-­‐)     connects  to  ground  
  11. 11. Control •  Arduino-compatible Microcontroller co- ordinates robot inputs (sensors) and outputs (actuators) •  See http://arduino.cc/ Anna Gerber Intro to Electronics in Python
  12. 12. PyFirmata •  https://github.com/tino/pyFirmata •  Communicates with the Arduino using the Firmata protocol Install using pip: pip  install  pyfirmata   Anna Gerber Intro to Electronics in Python
  13. 13. Loading Firmata onto the Arduino •  Once-off setup to prepare our Arduino for use with PyFirmata: –  Connect the microcontroller board via USB –  Launch Arduino IDE and open the Firmata sketch via the menu: File  >  Examples  >  Firmata  >   StandardFirmata   –  Select your board type (e.g. Arduino Nano w/ ATmega328) via Tools  >  Board   –  Select the port for your board via Tools  >   Serial  Port  > (the port of your Arduino) 
 e.g. /dev/tty.usbserial-A9GF3L9D –  Upload the program by clicking on Upload   –  Close the IDE Anna Gerber Intro to Electronics in Python
  14. 14. BLINKING AN LED Anna Gerber Intro to Electronics in Python
  15. 15. Connecting an LED to the Arduino •  Unplug the Arduino! •  Attach long lead of LED to pin 13 of Arduino •  Connect resistor to cathode of resistor and ground rail of breadboard •  Connect GND pin of Arduino to ground rail of breadboard using a jumper wire Anna Gerber Intro to Electronics in Python
  16. 16. Creating the program 1.  Create a Python program file (e.g. blink.py) 2.  Edit it using a text editor e.g. SublimeText 3.  At the start of your program import the library import  pyfirmata   Anna Gerber Intro to Electronics in Python
  17. 17. Creating the board We create a Board object which corresponds to our Arduino-compatible microcontroller board and store it in a variable. We need to provide the port as a parameter: board  =  pyfirmata.Arduino("/dev/tty.usbserial-­‐A9QPTF37")   Anna Gerber Intro to Electronics in Python
  18. 18. Controlling the LED •  Then we can control the LED via the pin it is connected to (in this case, pin 13) •  Use a variable for the pin number to make it easier to change later –  PIN  =  13   •  Turn on LED on pin 13 –  board.digital[PIN].write(1)   •  Turn off LED on pin 13 –  board.digital[PIN].write(0)   Anna Gerber Intro to Electronics in Python
  19. 19. Delayed behaviour •  Use the pass_time function to delay functions by a certain number of seconds e.g. blink LED on then off after one second:    board.digital[PIN].write(0)      board.pass_time(1)      board.digital[PIN].write(1)   Anna Gerber Intro to Electronics in Python
  20. 20. Repeating behaviour (loops) Use a while loop to blink indefinitely: while  True  :   board.digital[PIN].write(0)   board.pass_time(1)   board.digital[PIN].write(1)   board.pass_time(1)   Anna Gerber Intro to Electronics in Python
  21. 21. The entire blink program import  pyfirmata   PORT  =  "/dev/tty.usbserial-­‐A9QPTF37"   PIN  =  13   board  =  pyfirmata.Arduino(PORT)   while  True:          board.digital[PIN].write(0)          board.pass_time(1)          board.digital[PIN].write(1)          board.pass_time(1)   Anna Gerber Intro to Electronics in Python
  22. 22. Running the program from Terminal •  Open the Terminal app •  Change directory to the location where you have saved your code e.g. 
  >  cd  ~/Desktop/code/   •  Run your program using Python e.g.
  >  python blink.py
 •  Hit control-C to stop the program Anna Gerber Intro to Electronics in Python
  23. 23. Connecting to iPython Notebook •  We will use iPython Notebook running on Raspberry Pi •  Plug into Raspberry Pi via ethernet (connect to DHCP server on Pi) •  Open 192.168.1.1:8888 in your browser Anna Gerber Intro to Electronics in Python
  24. 24. How to setup the software at home •  Install Arduino IDE –  Optional, only required if you want to load Firmata again or experiment with programming the Arduino using C++ •  Install Python •  Install PyFirmata   •    Install a code editor e.g. Atom (Mac only), SublimeText if you don't already have one or install iPython Notebook Anna Gerber Intro to Electronics in Python
  25. 25. Where to find out more •  Electricity –  https://www.khanacademy.org/science/physics/ electricity-and-magnetism/v/circuits--part-1 •  Arduino Playground –  http://playground.arduino.cc/interfacing/python •  Sample code for Freetronics kit –  https://gist.github.com/AnnaGerber/ 26decdf2aa53150f7515 Anna Gerber Intro to Electronics in Python

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