Introduction

sudo apt-get update

sudo apt-get install git

git clone http://github.com/adafruit/Adafruit-Raspberry-Pi-Python-Code.git
cd Adafruit-Raspberry-Pi-Python-Code
ls

sudo apt-get update

sudo apt-get install python-dev

sudo apt-get install python-rpi.gpio

sudo apt-get install alsa-utils
sudo apt-get install mpg321
sudo apt-get install lame

sudo modprobe snd_bcm2835
sudo amixer cset numid=3 1

aplay file_name.wav
speaker-test -t sine -f 440 -c 2 -s 1
mpg321 "file_name.mp3"

• (3) 10k pull-up resistors
• (3) Momentary push-button switches

find . -regex ".*\.\(wav\|aif\|wave\|aiff\)"

find / -iname "*.mp3" -print

emacs raspi-audio-button.py

#!/usr/bin/env python
 
from time import sleep
import os
import RPi.GPIO as GPIO
 
GPIO.setmode(GPIO.BCM)
GPIO.setup(23, GPIO.IN)
GPIO.setup(24, GPIO.IN)
GPIO.setup(25, GPIO.IN)
 
while True:
        if ( GPIO.input(23) == False ):
                os.system('mpg321 name_of_file.mp3 &')
        if ( GPIO.input(24) == False ):
                os.system('mpg321 name_of_file.mp3 &')
        if ( GPIO.input(25)== False ):
                os.system('mpg321 name_of_file.mp3 &')
        sleep(0.1);

$ chmod +x raspi-audio-button.py 

Configuring

Using the Adafruit Console Cable

1. For Mac ownload and install the Console Cable (Click here for Lion).
   
   
   
   Install PL2303 driver. This will save a zip file called "PL2303_Prolific_DriverInstaller_v1_7_0.zip". Unzip this onto the desktop and within the folder run the installer called PL2303_Prolific_DriverInstaller_v1.7.0.exe
   Follow the steps here.

   ---

2. The Console lead has four female connections that can be plugged directly onto the GPIO header of the Raspberry Pi.
   
   The serial lead is going to power the Raspberry Pi. So, DO NOT attach the Pi's USB power adapter. Or, if you want to power the Pi from the USB power adapter, leave the Red lead from the Serial lead unattached.
   
   
   • The red lead should be connected to 5V or leave unattached
   • The black lead to GND
   • The white lead to TXD
   • The green lead to RXD
   The connections are to the outside pin connections of the GPIO header
   
   Image from Adafruit's Raspberry Pi Lesson 5. Using a Console Cable
   
   
   
   

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3. Plug in the USB lead and you should see the Pi's power LED
   
   

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4. Open a Terminal window and issue the command:

   ls /dev/*PL*

   or

   screen /dev/cu.PL2303-00001004 115200

   Type the line above as far as "cu.PL" then press the TAB key to auto-complete to whatever your device is called, before adding 115200 (which is the baud rate) to the end.
   
   

   ---

5. To start communication with the Pi, press ENTER and you should see the login prompt from the Pi. The default login is pi and the default password is raspberry
   
   

   ---

6. You are connected and can use the command line to navigate around your Pi.
   
   

   ---

Servo Motors

# Servo Control
import time
def set(property, value):
    try:
        f = open("/sys/class/rpi-pwm/pwm0/" + property, 'w')
        f.write(value)
        f.close()
    except:
        print("Error writing to: " + property + " value: " + value)
def setServo(angle):
    set("servo", str(angle))
    set("delayed", "0")
    set("mode", "servo")
    set("servo_max", "180")
    set("active", "1")
    delay_period = 0.01
    while True:
        for angle in range(0, 180):
            setServo(angle)
            time.sleep(delay_period)
    for angle in range(0, 180):
        setServo(180 - angle)
        time.sleep(delay_period)

Input

1. Be careful to get the DS18B20 the right way around. The curved edge should be to the left as shown in the figure below. If you put it the wrong way around, it will get hot and then break.
   
   Image from Adafruit's Raspberry Pi Lesson 11. DS18B20 Temperature Sensing
   
   If you are using the waterproof version of the DS18B20 then the device has three leads, red, black and yellow. The bare copper screening lead that does not need to be connected:
   Image from Adafruit's Raspberry Pi Lesson 11. DS18B20 Temperature Sensing
   
   

   ---

2. Run the following commands:

   sudo modprobe w1-gpio
   sudo modprobe w1-therm
   cd /sys/bus/w1/devices
   ls
   

   
   
   

   ---

3. Navigate to the directory in devices that starts with '28-'):

   cd 28-xxxx (change this to match what serial number pops up)

   
   
   

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4. Run the following commands:

   cat w1_slave

   
   
   

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5. The interface tells you if there is a valid temperature to read. The response will either have YES or NO at the end of the first line. If it is yes, then the temperature will be at the end of the second line, in 1/000 degrees C.
   
   If you have more than one Sensor connected, you'll see multiple 28-xxx files. Each one will have the unique serial number so you may want to plug one in at a time.
   
   

   ---

6. Here is a Python program to deal with any failed messages and report the temperature in degrees C and F every second:

   import os
   import glob
   import time
   
   os.system('modprobe w1-gpio')
   os.system('modprobe w1-therm')
   
   base_dir = '/sys/bus/w1/devices/'
   device_folder = glob.glob(base_dir + '28*')[0]
   device_file = device_folder + '/w1_slave'
   
   def read_temp_raw():
       f = open(device_file, 'r')
       lines = f.readlines()
       f.close()
       return lines
   
   def read_temp():
       lines = read_temp_raw()
       while lines[0].strip()[-3:] != 'YES':
           time.sleep(0.2)
           lines = read_temp_raw()
       equals_pos = lines[1].find('t=')
       if equals_pos != -1:
           temp_string = lines[1][equals_pos+2:]
           temp_c = float(temp_string) / 1000.0
           temp_f = temp_c * 9.0 / 5.0 + 32.0
           return temp_c, temp_f
   
   while True:
       print(read_temp())
       time.sleep(1)
   

   Save the file as thermometer.py
   
   

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7. Run the program:

   sudo python thermometer.py

   
   
   

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8. Try putting your finger over the sensor to warm it up.
   
   

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9. You can add additional DS18B20 sensors in parallel - connect all the sensors' VCC, data and ground pins together. Use a single 4.7K resistor. You will see multiple /sys/bus/w1/devices/28-nnnnn directories, each one having the unique serial number as the directory name. The python example code only works for one sensor right now so you will have to adapt it if you want it to read from different sensors at once.
   
   

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