Basic Electronics and Raspberry Pi IO Programming

Size: px

Start display at page:

Download "Basic Electronics and Raspberry Pi IO Programming"

Aileen Rodgers
5 years ago
Views:

1 Basic Electronics and Raspberry Pi IO Programming Guoping Wang Indiana University Purdue University Fort Wayne IEEE Fort Wayne Section February 18, 2016

2 Table of Contents 1 Safety Guideline 2 Pi Electronic Kits 3 Electronics Electricity Circuit Components 4 Raspberry Pi I/O 5 What Next G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

3 Table of Contents 1 Safety Guideline 2 Pi Electronic Kits 3 Electronics Electricity Circuit Components 4 Raspberry Pi I/O 5 What Next G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

4 Project Guideline Disconnect the power before making any connections! Before power on your Raspberry Pi, make sure that your circuit has been checked by the instructor. Do NOT short circuit the power. Failure to follow these steps may fry the Raspberry Pi kit G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

5 Table of Contents 1 Safety Guideline 2 Pi Electronic Kits 3 Electronics Electricity Circuit Components 4 Raspberry Pi I/O 5 What Next G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

6 Parts List CanaKit GPIO to Breadboard Interface Board GPIO Ribbon Cable GPIO and Resistor Colors Quick Reference Cards Breadboard one RGB LED 32 x Jumper Wires 2 x Red LEDs, 2 x Green LEDs, 2 x Yellow LEDs, 2 x Blue LEDs 2 x Push Button Switches 10 x 220 Ohm Resistors, 5 x 10K Ohm Resistors G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

7 about Parts Polarized vs non-polarized Physics and chemistry in a tiny package Explain Data Sheets Sparkfun online tutorial G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

8 Table of Contents 1 Safety Guideline 2 Pi Electronic Kits 3 Electronics Electricity Circuit Components 4 Raspberry Pi I/O 5 What Next G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

9 Electricity What is electricity? What kinds are there? What can it do? What are the dangers? What is DC vs AC? What are some power sources? G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

10 Circuit Breadboard A breadboard allows us to neatly wire circuits without the need for soldering. It is good for prototyping a circuit. Literally started out as a bread board with nails. G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

11 Circuit Electric Circuit Combination of electronic parts, wires connected between power sources. It s like a physical program. It s also like setting up dominoes in sequence. 220 ohm 3.3V G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

12 Components Electricity vs water Electricity is like water. Voltage is the height, measured in Volts (V) Current is the amount of water, measured in Amps (A). Resistance is any obstacle that slows down the water, measured in Ohms Ω. G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

13 Components Ohm s Law V = I R Voltage = Current * Resistance I (current) R (resistor) V (power source) G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

14 Components Resistors Resistors provide a specific amount of resistance to a path in a circuit or wire. Ohm s law is used to calculate the propertiesrelatedto resistance. Resistors are color coded. G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

15 Components Resistor Reading ohm resistor? How can I read resistor s value? To distinguish left from right there is a gap between C and D bands. band A is the first significant figure of component value (left side) band B is the second significant figure (Some precision may have a 3rd significant figure) band C is the decimal multiplier band D if present, indicates tolerance of value in percent (no band means 20 G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

16 Components Resistor Codes in table G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

17 Components LEDs Light Emitting Diodes (LED) Diode Symbol + Arrows for light Points to Ground G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

18 Components. G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

19 Components LED-RGB Clear Common Anode LED - Common Anode, Datasheet and product information at: RGB- Common Anode LED G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

20 Components Serial vs Parallel Circuits in serial Share the same current Have different voltages Circuits in parallel Have different currents Share the same voltage G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

21 Table of Contents 1 Safety Guideline 2 Pi Electronic Kits 3 Electronics Electricity Circuit Components 4 Raspberry Pi I/O 5 What Next G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

22 Python and C Package supports for Raspberry Pi Rpi.GPIO Package for beginner WiringPi Package for C and Python for intermediate learner PIGPIO Package for C and Python for advanced programmer G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

23 RPi.GPIO Install and Tutorial Rpi.GPIO Package Install/Upgrade RPi.GPIO Tutorial from raspi.tv RPi.GPIO Official Website G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

24 RPi.GPIO Installation The newest version of Raspbian has the RPi.GPIO library pre-installed. You ll probably need to update your library, so using this command line, run: RPi.GPIO Version sudo python import RPi.GPIO as GPIO GPIO.VERSION The current version of RPi.GPIO is You need to update to a newer version, run RPi.GPIO Update sudo apt-get update sudo apt-get upgrade G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

25 GPIO.cleanup() GPIO.cleanup() needs to be called when you exit your program to clean up all the ports you ve used. import RPi. GPIO as GPIO # the rest of your code would go here # when your code ends, the last line before the program exits would be GPIO. cleanup () # remember, a program doesn t necessarily exit at the last line! G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

26 Better Way to use GPIO.cleanup() When keyboard interrupt (CTRL+C), GPIO.cleanup() is called. import RPi. GPIO as GPIO # here you would put all your code for setting up GPIO, # we ll cover that tomorrow # initial values of variables etc... counter = 0 try : # here you put your main loop or block of code while counter < : # count up to takes ~20 s counter += 1 print (" Target reached :", counter ) except KeyboardInterrupt : # here you put any code you want to run before the program # exits when you press CTRL +C print ("\ n", counter ) # print value of counter except : # this catches ALL other exceptions including errors. # You won t get any error messages for debugging # so only use it once your code is working print (" Other error or exception occurred!") finally : GPIO. cleanup () # this ensures a clean exit G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

27 Safety Guideline Pi Electronic Kits Electronics Raspberry Pi I/O What Next RPi.GPIO Pin Numbering Two pin numberings in Raspberry Pi: BCM and BOARD. You can use only one number system in one program. For example, GPIO14 (pin number 8), BCM: pin number 14 BOARD: pin number 8 ($, ($, G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

28 Setup RPi.GPIO number system At the top of every script, after importing the RPi.GPIO module, we can set our GPIO numbering mode. (either BCM or BOARD). import RPi. GPIO as GPIO # for GPIO numbering, choose BCM GPIO. setmode ( GPIO. BCM ) # or, for pin numbering, choose BOARD GPIO. setmode ( GPIO. BOARD ) # but you can t have both, so only use one!!! G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

29 Set up GPIO as input import RPi. GPIO as GPIO GPIO. setmode ( GPIO. BCM ) # set up BCM GPIO numbering GPIO. setup (25, GPIO. IN) # set GPIO 25 as input Reading Inputs: Inputs are Boolean values: 1 or 0 (True or False), (GPIO.HIGH or GPIO.LOW) (all of them are the same). For example, import RPi. GPIO as GPIO GPIO. setmode ( GPIO. BCM ) # set up BCM GPIO numbering GPIO. setup (25, GPIO. IN) # set GPIO 25 as input if GPIO. input ( 25): # if port 25 == 1 print (" Port 25 is 1/ GPIO. HIGH / True " ) # or store its value in a variable to use in a different button_ press = GPIO. input ( 25) G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

30 GPIO Input sample code import RPi. GPIO as GPIO GPIO. setmode ( GPIO. BCM ) # set up BCM GPIO numbering GPIO. setup (25, GPIO. IN) # set GPIO 25 as input if GPIO. input (25): # if port 25 == 1 print (" Port 25 is 1/ GPIO. HIGH / True " ) else : print (" Port 25 is 0/ GPIO. LOW / False " ) GPIO. cleanup () # clean up after yourself The above is not really complete yet, what we need to do is add: loop, so we can make it read more than once time delay, so it wont read the port thousands of times per second circuit with a button, so we can change the status of the port and see the input status change on the screen try: except KeyboardInterrupt: block so we can exit cleanly (we covered this yesterday) G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

31 Pin 25 input Circuit 3.3V 220 ohm Pi pin 25 10K When the switch is NOT closed, the 10K resister pulls down pin 25 to 0 Volts. When the switch is pressed, the voltage to pin 25 is digital High. G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

32 GPIO Input Reading Python code import RPi. GPIO as GPIO from time import sleep # this lets us have a time delay ( see line GPIO. setmode ( GPIO. BCM ) # set up BCM GPIO numbering GPIO. setup (25, GPIO. IN) # set GPIO 25 as input try : while True : # this will carry on until you hit CTRL +C if GPIO. input (25): # if port 25 == 1 print (" Port 25 is 1/ GPIO. HIGH / True - button pressed ") else : print (" Port 25 is 0/ GPIO. LOW / False - button not pressed ") sleep (0.1) # wait 0.1 seconds except KeyboardInterrupt : GPIO. cleanup () # clean up after yourself G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

33 RPi.GPIO Outputs import RPi. GPIO as GPIO # import RPi. GPIO module GPIO. setmode ( GPIO. BCM ) # choose BCM or BOARD GPIO. setup ( port_or_pin, GPIO. OUT ) # set a port / pin as an output GPIO. output ( port_or_pin, 1) # set port / pin value to 1/ GPIO. HIGH / GPIO. output ( port_or_pin, 0) # set port / pin value to 0/ GPIO. LOW / F You can also set the initial value of the output at the time of setting up the port with initial=x optional extra argument GPIO.setup(port_or_pin, GPIO.OUT, initial=1) or GPIO.setup(port_or_pin, GPIO.OUT, initial=0) G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

34 Pin 24 Output Circuit Pi pin ohm When pin 24 outputs digital 0 (0V), LED is turned off. When pin 24 outputs digital 1 (3.3V), LED is turned on. G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

35 RPi.GPIO Outputs Sample code import RPi. GPIO as GPIO # import RPi. GPIO module from time import sleep # lets us have a delay GPIO. setmode ( GPIO. BCM ) # choose BCM or BOARD GPIO. setup (24, GPIO. OUT ) # set GPIO24 as an output try : while True : GPIO. output (24, 1) # set GPIO24 to 1/ GPIO. HIGH / True sleep (0.5) # wait half a second GPIO. output (24, 0) # set GPIO24 to 0/ GPIO. LOW / False sleep (0.5) # wait half a second except KeyboardInterrupt : # trap a CTRL +C keyboard interrupt GPIO. cleanup () # resets all GPIO ports used by thi G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

36 Inputs/Outputs and Pull-ups and Pull-downs Recaptures of inputs/outputs with RPi.GPIO package. import RPi. GPIO as GPIO # import RPi. GPIO module GPIO. setmode ( GPIO. BCM ) # choose BCM or BOARD GPIO. setup ( port_or_pin, GPIO. IN) # set a port / pin as an input GPIO. setup ( port_or_pin, GPIO. OUT ) # set a port / pin as an output GPIO. output ( port_or_pin, 1) # set an output port / pin value to 1/ GPIO. output ( port_or_pin, 0) # set an output port / pin value to 0/ i = GPIO. input ( port_or_pin ) # read status of pin / port and assign G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

37 Combined Input/Output Circuit Pi pin ohm Pi pin ohm 10K 3.3V Every 0.1s, the program checks the button status: If pressed, button status is displayed and LED is switched on. Otherwise, if not pressed (input port 25 ==0), button status is displayed and LED is switched off. It keeps going until CTRL+C is pressed, then the ports are cleaned up before exit. G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

38 Python Sample Code import RPi. GPIO as GPIO from time import sleep # this lets us have a time delay ( see line GPIO. setmode ( GPIO. BCM ) # set up BCM GPIO numbering GPIO. setup (25, GPIO. IN) # set GPIO25 as input ( button ) GPIO. setup (24, GPIO. OUT ) # set GPIO24 as an output ( LED ) try : while True : # this will carry on until you hit CTRL +C if GPIO. input (25): # if port 25 == 1 print (" Port 25 is 1/ HIGH / True - LED ON ") GPIO. output (24, 1) # set port / pin value to 1/ HIGH / else : print (" Port 25 is 0/ LOW / False - LED OFF ") GPIO. output (24, 0) # set port / pin value to 0/ LOW / F sleep (0.1) # wait 0.1 seconds finally : # this block will run no matter how the try GPIO. cleanup () # clean up after yourself G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

39 Pull-up and Pull-down In the button circuit, were using resistors to pull-down the port. This gives it a default state of 0V (0, LOW, False). If you have no pull-up or pull-down resistors attached to an input port, its status is not clearly defined. It is floating. It is susceptible to random electromagnetic radiation from you, from any devices near or far and from the environment. Any wires attached to the GPIO ports act as antennae for this radiation (its mostly radio waves). Internal Pull-up and Pull-Down: Raspberry Pi CPU has built-in pull-up and pull-down resistors which can be enabled in software. We can eliminate our pull-down resistors for the button - as long as we enable the internal ones. GPIO.setup(port or pin, GPIO.IN, pull up down=gpio.pud DOWN) G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

40 Circuit with Pull-Down enabled Pi pin V 220 ohm 220 ohm GPIO.setup(25, GPIO.IN) # set GPIO25 as input (button) to GPIO.setup(25, GPIO.IN, pull up down=gpio.pud DOWN) # set GPIO25 as input (button) Pi pin 25 G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

41 Python Sample Code with Pull-down import RPi. GPIO as GPIO from time import sleep # this lets us have a time delay ( see line GPIO. setmode ( GPIO. BCM ) # set up BCM GPIO numbering GPIO. setup (25, GPIO.IN, pull_up_down = GPIO. PUD_DOWN ) # set GPIO25 as GPIO. setup (24, GPIO. OUT ) # set GPIO24 as an output ( LED ) try : while True : # this will carry on until you hit CTRL +C if GPIO. input (25): # if port 25 == 1 print (" Port 25 is 1/ HIGH / True - LED ON ") GPIO. output (24, 1) # set port / pin value to 1/ HIGH / else : print (" Port 25 is 0/ LOW / False - LED OFF ") GPIO. output (24, 0) # set port / pin value to 0/ LOW / F sleep (0.1) # wait 0.1 seconds finally : # this block will run no matter how the try GPIO. cleanup () # clean up after yourself G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

42 Table of Contents 1 Safety Guideline 2 Pi Electronic Kits 3 Electronics Electricity Circuit Components 4 Raspberry Pi I/O 5 What Next G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

43 What Next Book: Python for Kids focus on software Book: Hello World!: Computer Programming for Kids and Other Beginners Software Book: RPi.GPIO Package, WiringPI Package, PIGPIO Package Raspberry Pi I/O Interface Raspberry Pi Sunfounder Super Kit: Sunfounder Project Super Starter Kit for Raspberry Pi Model B+ $41.99 Sunfounder Super Kit online Resource G. Wang (IPFW, IEEE FW Section) Electronics and Pi I/O February 18, / 41

Raspberry Pi Activity 2: My Binary Addiction...Reloaded

The Science of Computing II Living with Cyber Raspberry Pi Activity 2: My Binary Addiction...Reloaded In this activity, you will re-implement the one-bit binary adder that was the subject of Raspberry