The Raspberry Pi is a small credit-card sized linux computer. Developers and hobbyists around the world are creating miraculous applications and projects, and now you can join them. Last year we presented Raspberry Pi, What We Have Learned So Far, This year's presentation covers the first steps to using your Pi. From the basics, like burning your SD Card to creating a News Reader, you will learn GPIO Basics and simple Python tools. Communication between other components using SPI or I2C will also be covered. It is recommended, but not required that you have a Raspberry Pi, some knowledge of Python and simple electronics.

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. Model B

8. Raspberry

9. Pi
Text
“Take

10. a

11. 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

12. BModel

13. A

15. Arduino

16. UNO

18. :

20. Arduino

21. MEGA

23. :

26. Raspberry

27. Pi

29. 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

30. Initial Setup

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

32. Recommended

33. SD

34. Cards
•Class

35. 4

36. Minimum
•2

37. GB

38. or

39. More
•Major

40. Brands

41. are

42. Better!

43. 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:
in a Terminal--
sudo diskutil unmount /dev/disk1s1
sudo dd bs=1m if=(Insert Location of .img) of=(SD Card)
sync
sudo diskutil eject /dev/rdisk1

45. Demo

46. GPIO

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

49. Python

50. Simple

51. Blink

52. App

53. #! /usr/bin/python
import time
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
#use the common numeration,
#also the one found on the Adafruit Cobbler
led = 25
delay = .5
GPIO.setup(led, GPIO.OUT)
#Set 'led' as and Output
while True:
GPIO.output(led, True) #led On
time.sleep(delay) #wait 'delay' seconds
GPIO.output(led, False) #led off
time.sleep(delay) #wait another 'delay' seconds

55. Demo

56. Analogue

57. Input

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

59. 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

60. 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

61. I2C
SPI

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

63. 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]

64. #! /usr/bin/python
#Written By Tom Paulus, @tompaulus, www.tompaulus.com
import time
import spidev
import RPi.GPIO as GPIO
spi = spidev.SpiDev()
light_adc = 7
statusLED = 25
GPIO.setmode(GPIO.BCM)
GPIO.setup(statusLED, GPIO.OUT)
print Press CTRL+Z to exit
def analogRead(port):
Read the given ADC port and preform the necessary shifting of bits
spi.open(0, 0)
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
while True:
GPIO.output(statusLED, True)
print analogRead(light_adc)
time.sleep(.125)
GPIO.output(statusLED, False)
time.sleep(.175)

66. Demo

67. Analogue

68. Input
Part

69. 2

70. 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

71. 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

72. I2C
SPI

73. #! /usr/bin/python
#Written By Tom Paulus, @tompaulus, www.tompaulus.com
import time
import spidev
import RPi.GPIO as GPIO
from Adafruit_LEDBackpack.Adafruit_7Segment import SevenSegment
import smbus
GPIO.setmode(GPIO.BCM)
segment = SevenSegment(address=0x70) # which port the display is
spi = spidev.SpiDev()
light_adc = 7
l = list()
statusLED = 25
print Press CTRL+Z to exit
GPIO.setup(statusLED, GPIO.OUT)
def analogRead(port):
Read the given ADC port and preform the necessary shifting of bits
spi.open(0, 0)
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

74. def movavg(list, length, value):
A function that smooths the results by averaging a list
#Courtesy Wolf Paulus
list.append(value)
if length len(list):
del list[0]
sum = 0
for x in list[:]:
sum += x
return sum / len(list)
while True:
GPIO.output(statusLED, True)
segment.writeInt(movavg(l, 4, analogRead(light_adc)))
time.sleep(.125)
GPIO.output(statusLED, False)
time.sleep(.175)
**This program uses a modified library**

76. Demo

77. Using

78. Outside

79. Data

80. JSON

81. JavaScript

82. Object

83. 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
}
]
}

84. JSON

85. meet

86. 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
}
]
}

88. What

89. time

90. is

91. it

92. in

93. city?

94. #! /usr/bin/python
#Written By Tom Paulus, @tompaulus, www.tompaulus.com
import lib.requests as requests
import time
timeURL = 'http://json-time.appspot.com/time.json?tz='
zone = 'America/Phoenix'
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)

96. Displaying

97. the

98. Data

99. News Client

100. class Scroller():
def splitString(self, s, lineLength):
# s = 'The Quick Brown Fox Jumps Over The Lazy Dog' #Test String
string = ''
length = 0
k = 0 #Counter Variable
wordLength = list()
strings = list()
lines = list()
words = s.strip().split()
for k in range(0, len(words)): #Make a list of the word lengths
length = len(words[k])
wordLength.append(length)
k = 0 #Reset Counter
while k len(words):
if len(string) + len(words[k]) + 1 lineLength:
if len(string) == 0:
string += words[k]
else:
string = string + ' ' + words[k]
k += 1
else:
strings.append(string)
string = ''
if k == len(words):
strings.append(string)
string = ''
k = 0 #Reset Counter

101.
while k len(strings): #Format for Our Display
if k == len(strings) - 1:
line = strings[k]
lines.append(line)
break
else:
line = strings[k] + 'n' + strings[k + 1]
lines.append(line)
k += 2
return lines
if __name__ == '__main__':
s = raw_input('Enter the string to be separatedn').replace('n', '')
tools = Scroller()
print tools.splitString(s, 16)

102. The Quick Brown Fox Jumps Over The Lazy Dog
['The Quick BrownnFox Jumps Over', 'The Lazy Dog']

103. class NewsAPI:
def get(self,count,key):
Get the homepage form HackerNews
:return: JSON object
url = 'http://api.usatoday.com/open/articles/topnews/news?count='+str(count)+'days=0page=0encoding=jsonapi_key='+key
d = requests.get(url)
JSON = d.json()
return JSON
while True:
z = 0
if update:
nJson = API.get(15, API_KEY)
length = len(nJson['stories'])
for x in range(0, length):
articles.append(nJson['stories'][x]['title'])
update = False
display = tools.splitString(articles[currentTitle], 16)
for y in range(0, len(display)):
z += 1
Timer(y * 2, rotate, args=[display[y]]).start()
time.sleep(z * 2 + 2)
currentTitle = (currentTitle + 1) % len(articles)

104. Demo

105. Wea!er Client

106. 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!')

107. 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

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.What’s new in the News?

111. Slides:
Code Used in this Talk:
http://tompaulus.com/talks
https://github.com/tpaulus/DCC-April13
Email:
tom@tompaulus.com

112. Slides:
Code Used in this Talk:
http://tompaulus.com/talks
https://github.com/tpaulus/DCC-April13
Email:
tom@tompaulus.com