Code for the LCES from Multigrad's blog ( http://multigrad.blogspot.ca/ )

random_servo.py

"""
Example of how to move randomly two servos plugged in the 5th and 6th channel
(slot 4 & 5) of a Pololu Micro Maestro 6.

This script requires pyserial.
"""

from random import randrange, uniform
from time import sleep
from struct import pack

import serial


class PololuConn(object):
    """Encapsulates Pololu communications."""
    def __init__(self, port, port_speed=9600):
        """Creates a connection to the Pololu.

        :param port:
            The serial port linked to the Pololu. Is of the form r'\\\\.\\COM3'
            on Windows and '/dev/ttyUSB1' on Linux.
        :type port: str
        :param port_speed: The speed of the port (default 9600)
        :type port_speed: int
        :exception ValueError:
            Will be raised when parameter are out of range, e.g. baud rate,
            data bits.
        :exception SerialException:
            In case the device can not be found or can not be configured.
        """
        self.ser = serial.Serial(port, port_speed)

    def setSpeed(self, channel, speed):
        """Sets the speed of the servos plugged in channels.
        The protocol for the Pololu is described in this page:
        # http://www.pololu.com/docs/0J40/5.e

        :param channels: channel to change speed.
        :type channels: int
        :param speed: Speed to set the servo.
        :type speed: int
        """
        self.ser.write(pack("BBBB", 0x87, channel, speed, 0x00))

    def move(self, channel, destination):
        """Move the servos plugged in channels to their destinations.
        Motion is done using the Mini-SSC protocol described in this page:
        http://www.pololu.com/docs/0J40/5.c

        :param channels: Channel to move.
        :type type: int
        :param destinations: Destination angle between 0 and 255.
        :type destinations: int
        """
        self.ser.write(pack("BBB", 0xff, channel, destination))

    def close(self):
        """Close the connection to the Pololu."""
        self.ser.close()


def main():
    """Connects to a Pololu and then moves randomly its channels 4 and 5."""
    # These constants defines the servo range.
    SERVOS_USED = (4, 5)
    SERVO_RANGE = (0x40, 0xA0)
    DELAY_RANGE = (0.05, 0.70)

    conn = PololuConn(port=r'\\.\COM3')

    # Set speed
    for servo in SERVOS_USED:
        conn.setSpeed(servo, 0x15)

    # Main random destination loop
    try:
        while True:
            for servo in SERVOS_USED:
                destination = randrange(*SERVO_RANGE)
                conn.move(servo, destination)
            sleep(uniform(*DELAY_RANGE))
    except KeyboardInterrupt:
        conn.close()


if __name__ == '__main__':
    main()