1. Getting Started with
Raspberry Pi
Tom Paulus
www.tompaulus.com
@tompaulus

2. Recommended

3. Books

4. Hardware

5. Model B

6. Model A

7. Raspberry

8. Pi
Text
“Take

9. a

10. bite!”
CPU
Broadcom ARM11
SoC
Broadcom ARM11
SoC
Clock
Speed
Up to 1GHz
ClockSpeed*
Up to 1GHz
ClockSpeed*
Memory 256 MB 512 MB
USB 1 USB Port 2 USB Ports
Network None Onboard Ethernet
Model

11. BModel

12. A

14. Arduino

15. UNO

17. :

19. Arduino

20. MEGA

22. :

25. Raspberry

26. Pi

28. UNO MEGA DUE Pi Model A Pi Model B
Operating
Voltage
SRAM
FLASH-
Memory
Clock Speed
USB Host
Network
Audio /Video
Current I/O
pins
Digital I/O Pins
Analog Input
Pins
Price
5V 5V 3.3V 3.3V 3.3V
2 KB 8 KB 96 KB 265 MB 512 MB
32 KB 256 KB 512 KB up to 64 MB up to 64 MB
16 MHz 16 MHz 84 MHz 700 MHz* 700 MHz*
n/a n/a 1 1 2
n/a n/a n/a n/a
10/100 wired
Ethernet RJ45
n/a n/a n/a
HDMI, Composite
Video,
TRS-audio jack
HDMI, Composite
Video,
TRS-audio jack
40 mA 40 mA total 130 mA 2 to 16 mA 2 to 16 mA
14 (6 PWM) 54 (15 PWM) 54 (12 PWM) 17 (1 PWM) 17 (1 PWM)
6 16
12
2DAC Analog Out
0* 0*
$30 $59 $50 $25 $35

29. Initial Setup

30. http://www.raspberrypi.org/downloads

31. Recommended

32. SD

33. Cards
•Class

34. 4

35. Minimum
•2

36. GB

37. or

38. More
•Major

39. Brands

40. are

41. Better!

42. Creating Your Image
1. Download and Unzip the .img from www.raspberrypi.com
2. Format the SD Card to clear all Data
Windows Users:
Use
Win32DiskImager
Mac Users:
Use
Raspberry PI SD Installer OS X

44. Demo

45. GPIO

47. sudo apt-get install python-dev python-pip
sudo easy_install -U distribute
sudo pip install RPi.GPIO
Preparing

48. Python

49. Simple

50. Blink

51. App

52. from time import sleep
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
#use the common numeration,
#also the one found on the Adafruit Cobbler
led = 21 # GPIO Port to which the LED is
connected
delay = .5
GPIO.setup(led, GPIO.OUT) # Set 'led' as and Output
print Press CTRL+C to exit
try:
while True:
GPIO.output(led, True) # led On
sleep(delay) # wait 'delay' seconds
GPIO.output(led, False) # led Off
sleep(delay) # wait another 'delay' seconds
except KeyboardInterrupt:
GPIO.output(led, False)
finally:
GPIO.cleanup()
blink.py

53. Hardware

54. Demo

55. Analogue

56. Input

57. MCP3008 8-Channel 10-Bit ADC With SPI Interface
Ra!berryPi
wi ADC

58. SPI requires four signals:
clock (SCLK)
master output/slave input (MOSI)
master input/slave output (MISO)
slave select (SS) or (CS) chip-select
Ra!berryPi
Se#al Pe#pheral Interface Bus - SPI

59. pi@raspberrypi ~ $ cat /etc/modprobe.d/raspi-blacklist.conf
# blacklist spi and i2c by default (many users don't need them)
blacklist spi-bcm2708
blacklist i2c-bcm2708
Loading Kernel Modules:
Edit the raspi-blacklist.conf, so that the spi module gets loaded,
Reboot, and confirm with lsmod that ‘spidev’ and ‘spi_bcm2708’ are now loaded and
ls /dev/spi* shows two spi devices: /dev/spidev0.0 and /dev/spidev0.1
Installing Dependencies:
sudo apt-get install python-dev git-core
Install Python bindings for Linux SPI access through spidev:
cd ~
git clone git://github.com/doceme/py-spidev
cd py-spidev/
sudo python setup.py install
... which creates /usr/local/lib/python2.7/dist-packages/spidev.so
SPI

60. I2C
SPI

61. IN =[0000 0001][1CNL ----][---- ----]
(8+channel) 4
OUT=[---- ----][---- -XXX][XXXX XXXX] (10bit)
((r[1] 3) 8) + r[2]

62. IN =[0000 0001][1CNL ----][---- ----]
(8+channel) 4
OUT=[---- ----][---- -XXX][XXXX XXXX]
r[0] ((r[1] 3) 8) + r[2]
r = spi.xfer2( [1, (8+chnnl)4, 0] )
return ((r[1] 3) 8) + r[2]

63. def analogRead(port, bus=0, ce=0):
Read the given ADC port and preform the necessary shifting of bits
spi.open(bus, ce) # CE port that the MCP3008 is connected to
if (port 7) or (port 0):
print 'analogRead -- Port Error, Must use a port between 0 and 7'
return -1
r = spi.xfer2([1, (8 + port) 4, 0])
value = ((r[1] 3) 8) + r[2]
spi.close()
return value

64. import time
import spidev
import RPi.GPIO as GPIO
# This program reads an analogue value form a potentiometer attached to port 0 on the MCP3008 Chip
spi = spidev.SpiDev()
pot_adc = 0
statusLED = 23 # GPIO port that our Status led is connected to
GPIO.setmode(GPIO.BCM)
GPIO.setup(statusLED, GPIO.OUT)
print Press CTRL+C to exit
try:
while True:
GPIO.output(statusLED, True) # Status Led On
print analogRead(pot_adc) # Print read value
time.sleep(.125) # Wait a little
GPIO.output(statusLED, False) # Status Led Off
time.sleep(.175) # Wait a bit longer
except KeyboardInterrupt:
GPIO.output(statusLED, False)
finally:
GPIO.cleanup()
ADC1.py

65. Hardware

66. But, That’s Just Ugly!

67. Let’s Add a Display

68. I2C connects the same two signal lines
to all slaves. I.e. addressing is required
and all devices need a unique address
SDA - Serial Data
SCL - Serial Clock
Ra!berryPi
Inter-IC Bus - I2C

69. pi@raspberrypi ~ $ cat /etc/modprobe.d/raspi-blacklist.conf
# blacklist spi and i2c by default (many users don't need them)
blacklist spi-bcm2708
blacklist i2c-bcm2708
Loading Kernel Modules:
- Edit the raspi-blacklist.conf, so that the i2c module gets enabled.
- Add the following lines to /etc/modules
i2c-dev
i2c-bcm2708
Reboot, and confirm ls /dev/i2c*
shows
/dev/i2c-0
/dev/i2c-1
Installing Dependencies:
sudo apt-get install python-smbus i2c-tools
With i2c devices connected, run somthing like this, to discover devices addresses.
sudo i2cdetect -y 0
I2C

70. I2C
SPI

71. import time
import spidev
import RPi.GPIO as GPIO
from lib.Char_Plate.Adafruit_CharLCDPlate import Adafruit_CharLCDPlate
import smbus
GPIO.setwarnings(False)
GPIO.setmode(GPIO.BCM)
lcd = Adafruit_CharLCDPlate()
spi = spidev.SpiDev()
pot_adc = 0 # ADC
l = list() # List for Light Sensor Averaging
statusLED = 23
print Press CTRL+Z to exit
GPIO.setup(statusLED, GPIO.OUT)
lcd.backlight(lcd.ON)
lcd.clear()
def movavg(list, length, value):
A function that smooths the results by averaging a list
list.append(value)
if length len(list):
del list[0]
sum = 0
for x in list[:]:
sum += x
return sum / len(list)
ADC2.py

72. try:
while True:
# Change the Back-light based on what button has been pressed
if lcd.buttonPressed(lcd.DOWN):
lcd.backlight(lcd.ON)
if lcd.buttonPressed(lcd.UP):
lcd.backlight(lcd.OFF)
lcd.home()
GPIO.output(statusLED, True) # Status Led On
lcd.message('Potentiometer:n' + str(
movavg(l, 4, analogRead(pot_adc))) + ' ') # Read analog value
sleep(.1) # Wait a little
GPIO.output(statusLED, False) # Status Led off
sleep(.155) # Wait a bit longer
except KeyboardInterrupt:
GPIO.output(statusLED, False)
spi.close()
finally:
lcd.clear()
lcd.backlight(lcd.OFF)
GPIO.cleanup()
ADC2.py

73. MORE Inputs!!

74. ADC3.py
def colorChange(channel):
global color
if channel == green:
if color == lcd.ON:
color = lcd.GREEN
elif color == lcd.GREEN:
color = lcd.OFF
else:
color = lcd.ON
for i in range(3):
lcd.backlight(color)
sleep(.01)
sleep(bounce/1000)

75. try:
GPIO.add_event_detect(green, GPIO.RISING, callback=colorChange, bouncetime=bounce)
while True:
GPIO.output(statusLED, True) # Status Led On
l = movavg(light_Average, 4, analogRead(light_adc)) # Read the light sensor
lcd.home()
lcd.message('Pot: ' + str(analogRead(pot_adc)) + ' nLight: ' + str(l) + ' ')
GPIO.output(statusLED, False) # Status Led Off
sleep(rate) # Wait a little
except KeyboardInterrupt:
GPIO.output(statusLED, False)
spi.close()
finally:
lcd.clear()
lcd.backlight(lcd.OFF)
GPIO.cleanup()
ADC3.py

76. Hardware

77. Demo

78. Why?
try:
# Main Program
except KeyboardInterrupt:
# On Interrupt
finally:
GPIO.cleanup()

79. Somewhere, there is an Arduino laughing...
Current I/O
pins
Digital I/O Pins
Analog Input
Pins
Price
40 mA
14 (6 PWM)
6
$30

80. Using

81. Outside

82. Data

83. JSON

84. JavaScript

85. Object

86. Notation???
JSON??
{
firstName: John,
lastName: Smith,
age: 25,
address: {
streetAddress: 21 2nd Street,
city: New York,
state: NY,
postalCode: 10021
},
phoneNumber: [
{
type: home,
number: 212 555-1234
},
{
type: fax,
number: 646 555-4567
}
]
}

87. JSON

88. meet

89. JASON
{
firstName: John,
lastName: Smith,
age: 25,
address: {
streetAddress: 21 2nd Street,
city: New York,
state: NY,
postalCode: 10021
},
phoneNumber: [
{
type: home,
number: 212 555-1234
},
{
type: fax,
number: 646 555-4567
}
]
}

91. What

92. time

93. is

94. it

95. in

96. city?

97. #! /usr/bin/python
#Written By Tom Paulus, @tompaulus, www.tompaulus.com
import requests
import time
timeURL = 'http://json-time.appspot.com/time.json?tz='
zone = 'America/Los_Angeles'
while True:
timeJson = requests.get(timeURL + zone).json()
hour = timeJson['hour']
minute = timeJson['minute']
second = timeJson['second']
dateTime = timeJson['datetime']
print str(hour) + ':' + str(minute) + ':' + str(second)
print dateTime
time.sleep(1)
time.py

99. Displaying

100. the

101. Data

102. Weaer Client

103. while True:
if update:
lcd.clear()
lcd.message('Please WaitnFetching Data')
json = API.getLocation(locations.get(str(location) + 's'), locations.get(str(location) + 'c'),
token)
update = False
display = 0
if display == 0:
lcd.clear()
high = API.high(json, units_Temp)
low = API.low(json, units_Temp)
windSpeed = API.windSpeed(json, units_Speed)
windDir = API.winDir(json)
string1 = API.Display1(high, low, windSpeed, units_Speed, windDir, language)
lcd.message(string1)
if display == 1:
lcd.clear()
rain = API.rain(json)
humidity = API.humidity(json)
string2 = API.Display2(rain, humidity, language)
lcd.message(string2)
if display == 2:
lcd.clear()
lcd.message('More DatanComing Soon!')
Main.py

104. class WebAPI:
def getLocation(self, state, city, token):
d = requests.get(
'http://api.wunderground.com/api/' + str(token) + '/forecast/q/' + str(state) + '/' + str(city) +'.json')
json = d.json()
return json
def high(self, json, units):
high = str(json['forecast']['simpleforecast']['forecastday'][0]['high'][units])
return high
def low(self, json, units):
low = str(json['forecast']['simpleforecast']['forecastday'][0]['low'][units])
return low
def windSpeed(self, json, units):
windSpeed = str(json['forecast']['simpleforecast']['forecastday'][0]['avewind'][units])
return windSpeed
def winDir(self, json):
windDir = str(json['forecast']['simpleforecast']['forecastday'][0]['avewind']['dir'])
return windDir
WUndergroundAPI.py

105. USER Data!!
NSA I have some data for you...

106. User Data... Main.py
app_info_folder = '/etc/WeatherUnderground'
LocationData = app_info_folder + '/locations.conf'
try:
info = open(LocationData)
data = info.readlines()
length = int(str(data).count(',')) + 1
l1 = data[0].split(',')
for x in range(0, length):
l2 = l1[x].split(':')
locations[str(x) + 's'] = l2[0]
locations[str(x) + 'c'] = l2[1]
info.close()
except IOError:
lcd.message('WelcomenNew User!')
print 'Adding New Location...'
State = raw_input('Enter The name of the State your desired location is in, using the abbreviation -CAn')
City = raw_input('Now, Enter the name of the Cityn')
print 'nThank You!'
State = State.upper()
City = City.capitalize()
if not os.path.exists(app_info_folder):
os.makedirs(app_info_folder)
info = open(LocationData, 'w')
info.write(State + ':' + City)
locations = {'0' + 's': State, '0' + 'c': City}
info.close()

107. User Data... AddLocation.py
app_info_folder = '/etc/WeatherUnderground'
LocationData = app_info_folder + '/locations.conf'
info = open(data)
State = raw_input('Enter The name of the State your desired location is in, using the abbreviation -CAn')
City = raw_input('Now, Enter the name of the Cityn')
print 'nThank You!'
State = State.upper()
City = City.replace(' ','_')
if raw_input(Is this Information Correct? Type 'y'n) == 'y':
info = open(data, 'a')
info.write(',' + State + ':' + City)
info.close()

108. Demo

109. Summary
Wow! We have learned a lot!!
1. Initial Setup of the Raspberry Pi
2. Made a little LED blink
3. Dealt with an AnalogValue and Displayed it
4.The Basics of JSON
5. Got our feet wet by finding the Time in different places
6. Used our new Knowledge to find the Weather
7. Learned how to save Custom User Data

112. Slides:
Code Used in this Talk:
http://tompaulus.com/talks
https://github.com/tpaulus/SCC-SD2013
Email:
tom@tompaulus.com