The Raspberry Pi is a series of credit card–sized single-board computers developed in the UK by the Raspberry Pi Foundation with the intention of promoting the teaching of basic computer science in schools. The original Raspberry Pi and Raspberry Pi 2 are manufactured in several board configurations through licensed manufacturing agreements with Newark element14 (Premier Farnell), RS Components and Egoman. These companies sell the Raspberry Pi online. Egoman produces a version for distribution solely in China and Taiwan, which can be distinguished from other Pis by their red colouring and lack of FCC/CE marks. The hardware is the same across all manufacturers. The original Raspberry Pi is based on the Broadcom BCM2835 system on a chip (SoC), which includes an ARM1176JZF-S 700 MHz processor, VideoCore IV GPU, and was originally shipped with 256 megabytes of RAM, later upgraded (models B and B+) to 512 MB. The system has Secure Digital (SD) (models A and B) or MicroSD (models A+ and B+) sockets for boot media and persistent storage.

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Servo motor control using
raspberry-pi
 Servo motor theory.
 Controlling servo motor using pwm.

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Overview
 Servo motors are used for angular
positioning, such as in radio
control airplanes. They typically
have a movement range of 180 deg
but can go up to 210 deg.
 The output shaft of a servo does
not rotate freely, but rather is
made to seek a particular angular
position under electronic control.
 They are typically rated by torque
and speed. A servo rated 40 ounce-
in/.21 means that at 1 inch from
the hub, the servo can exert 40
ounces of force and move 60 deg in
0.21 sec.

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What makes a Servo
 The basic hobby servo has a 180:1
gear ratio. The motor is typically
small.
 Typically, a potentiometer (variable
resistor) measures the position of
the output shaft at all times so the
controller can accurately place and
maintain it’s setting.
Servo motors and are constructed out of basic DC
motors, by adding:
• some gear reduction
• a position sensor for the motor shaft
• an electronic circuit that controls the motor's
operation

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Feed-back loop
open-loop
closed-loop

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Connection with raspberry

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Code
# 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

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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)