2-Axis PWM Motor Controls in Python

# stick is a tuple of the form (x, y), that comes from the 2-axis controller (wii nunchuk)
# Both x and y are values from 0 - 255
# x=0 means "all the way left"
# y=0 means "all the way down"

# motors are controlled by PWM
# The only thing we change is the duty cycle,
# which is a value from 0 - 100

# Even though the duty cycle can only be 0 - 100, my move_motors() function
# takes values from -100 - 100. This is because if the value you pass
# for a motor is below 0 (a negative number), it will flip the pin that
# controls direction, and always pass the PWM pin a positive value
# Eg:
#   passing move_motors() the argument -58 for left_motor means:
#       flip the direction pin so motor spins backwards, and set duty cycle to 58

# Turn the 0-255 value of joystick into -128 - 127 value
left_right = stick[0] - 128
front_back = stick[1] - 128

left_motor = front_back + left_right
right_motor = front_back - left_right

# Scale factor defaults to 1
scale_factor = 1

# Calculate scale factor
if abs(left_motor) > 100 or abs(right_motor) > 100:
    # Find highest of the 2 values, since both could be above 100
    x = max(abs(left_motor), abs(right_motor))

    # Calculate scale factor
    scale_factor = 100.0 / x

# Use scale factor, and turn values back into integers
left_motor = int(left_motor * scale_factor)
right_motor = int(right_motor * scale_factor)

# Actually move the motors
move_motors(left_motor, right_motor)