servoControl.py

#!/usr/bin/env python
# Servo Control for Raspberry Pi with Adafruit servo control board 

#-------------------------------------------------------------------------------
#### Imports ####

import time
import sys

from Adafruit_PWM_Servo_Driver import PWM

#### Constants ####

#-------------------------------------------------------------------------------
#### Servo Initialization

# I2C address is 0x40
pwm = PWM(0x40)
# Servo frequency 60Hz
pwm.setPWMFreq(60)

# These values cannot be smaller than 100 and more than 700.  
_PAN_SERVO_CHANNEL = 2
_TILT_SERVO_CHANNEL = 3

_PAN_SERVO_LEFT = 250
_PAN_SERVO_RIGHT = 520
_PAN_SERVO_CENTER = 385

_TILT_SERVO_UP = 605
_TILT_SERVO_DOWN = 475
_TILT_SERVO_CENTER = 605

#### Objects ####

#-------------------------------------------------------------------------------
class ServoControl(object):
    # Make sure there is only one instance of ServoControl

    _instances=[]

    # Initialize the object
    def __init__(self):
        if ( len(self._instances)>1 ):
            print("ERROR: One instance of ServoControl is running already.")
            exit(1)
        self._instances.append(self)

#-------------------------------------------------------------------------------        
    # Move left
    def panLeft(self):
        pwm.setPWM(_PAN_SERVO_CHANNEL, 0, _PAN_SERVO_LEFT)

#-------------------------------------------------------------------------------        
    # Move left with exact degree
    def panExactLeft(self, degree):
        pwm.setPWM(_PAN_SERVO_CHANNEL, 0, degree)

#-------------------------------------------------------------------------------        
    # Move right
    def panRight(self):
        pwm.setPWM(_PAN_SERVO_CHANNEL, 0, _PAN_SERVO_RIGHT)

#-------------------------------------------------------------------------------        
    # Move right with exact degree
    def panExactRight(self, degree):
        pwm.setPWM(_PAN_SERVO_CHANNEL, 0, degree)
    
#-------------------------------------------------------------------------------        
    # Position pan servo in the middle
    def panCenter(self):
        pwm.setPWM(_PAN_SERVO_CHANNEL, 0, _PAN_SERVO_CENTER)

#-------------------------------------------------------------------------------        
    # Position pan servo exactly
    def panExactCenter(self, degree):
        pwm.setPWM(_PAN_SERVO_CHANNEL, 0, degree)

#-------------------------------------------------------------------------------        
    # Look up
    def tiltUp(self):
        pwm.setPWM(_TILT_SERVO_CHANNEL, 0, _TILT_SERVO_UP)

#-------------------------------------------------------------------------------        
    # Look up at exact angle
    def tiltExactUp(self, degree):
        pwm.setPWM(_TILT_SERVO_CHANNEL, 0, degree)

#-------------------------------------------------------------------------------        
    # Look down
    def tiltDown(self):
        pwm.setPWM(_TILT_SERVO_CHANNEL, 0, _TILT_SERVO_DOWN)

#-------------------------------------------------------------------------------        
    # Look down at exact angle
    def tiltExactDown(self, degree):
        pwm.setPWM(_TILT_SERVO_CHANNEL, 0, degree)

#-------------------------------------------------------------------------------        
    # Position tilt servo in the middle
    def tiltCenter(self):
        pwm.setPWM(_TILT_SERVO_CHANNEL, 0, _TILT_SERVO_CENTER)

#-------------------------------------------------------------------------------        
    # Position tilt servo exactly 
    def tiltExactCenter(self, degree):
        pwm.setPWM(_TILT_SERVO_CHANNEL, 0, degree)

#-------------------------------------------------------------------------------        
    # Reset servo orientation
    def resetServo(self):
        pwm.setPWM(_PAN_SERVO_CHANNEL, 0, _PAN_SERVO_CENTER)
        pwm.setPWM(_TILT_SERVO_CHANNEL, 0, _TILT_SERVO_CENTER)