servo_controller.py

import Tkinter as tk
import serial

ANGLE_MIN = 0
ANGLE_MAX = 180
SERVO_MIN = 1
SERVO_MAX = 4

# Assign Arduino's serial port address
#   Windows example
#     usbport = 'COM3'
#   Linux example
#     usbport = '/dev/ttyUSB0'
#   MacOSX example
#     usbport = '/dev/tty.usbserial-FTALLOK2'
usbport = '/dev/tty.usbserial-FTALLOK2'
# ser = serial.Serial(usbport, 9600, timeout=1)


class ServoController(object):

    def __init__(self):
        win = tk.Tk()
        win.wm_title('Servo Controller')
        # radio buttons for servo selection
        self.servo = tk.IntVar()
        for s in range(SERVO_MIN, SERVO_MAX + 1):
            rb = tk.Radiobutton(win, text='Servo {}'.format(s),
                                command=self.set_angle_from_memory,
                                variable=self.servo, value=s)
            rb.pack()
        # slider
        self.slider = tk.Scale(win, command=self.slider_move,
                               from_=ANGLE_MIN, to=ANGLE_MAX,
                               orient="horizontal")
        self.slider.pack()
        # remember servos angles
        self.angles = {}

    def set_angle_from_memory(self):
        angle = self.angles.get(self.servo.get(), 0)
        self.slider.set(angle)

    def slider_move(self, angle):
        servo = self.servo.get()
        if not servo:  # prevent calling "move" upon creation
            return
        angle = int(angle)
        self.move(servo, angle)
        self.angles[servo] = angle

    @staticmethod
    def move(servo, angle):

        if not (ANGLE_MIN <= angle <= ANGLE_MAX and
                SERVO_MIN <= servo <= SERVO_MAX):
            raise ValueError('Servo parameters out of bounds.')
        # send serial commands
        # ser.write(chr(255))
        # ser.write(chr(servo))
        # ser.write(chr(angle))

if __name__ == '__main__':
    s = ServoController()
    tk.mainloop()