Example of car front wheel

The car front wheel

from SunFounder_PCA9685 import Servo
import filedb

class Front_Wheels(object):
	''' Front wheels control class '''
	FRONT_WHEEL_CHANNEL = 0

	_DEBUG = False
	_DEBUG_INFO = 'DEBUG "front_wheels.py":'

	def __init__(self, debug=False, db="config", bus_number=1, channel=FRONT_WHEEL_CHANNEL):
		''' setup channels and basic stuff '''
		self.db = filedb.fileDB(db=db)
		self._channel = channel
		self._straight_angle = 90
		self.turning_max = 45
		self._turning_offset = int(self.db.get('turning_offset', default_value=0))

		self.wheel = Servo.Servo(self._channel, bus_number=bus_number, offset=self.turning_offset)
		self.debug = debug
		if self._DEBUG:
			print self._DEBUG_INFO, 'Front wheel PWM channel:', self._channel
			print self._DEBUG_INFO, 'Front wheel offset value:', self.turning_offset

		self._angle = {"left":self._min_angle, "straight":self._straight_angle, "right":self._max_angle}
			
		if self._DEBUG:
			print self._DEBUG_INFO, 'left angle: %s, straight angle: %s, right angle: %s' % (self._angle["left"], self._angle["straight"], self._angle["right"])
		self._debug('Set left wheel to #%d, PWM channel to %d' % (self.Motor_A, self.PWM_A))
		self._debug('Set right wheel to #%d, PWM channel to %d' % (self.Motor_B, self.PWM_B))

	def _debug(self, msg):
		if self._DEBUG:
			

	def turn_left(self):
		''' Turn the front wheels left '''
		if self._DEBUG:
			print self._DEBUG_INFO, "Turn left"
		self.wheel.write(self._angle["left"])

	def turn_straight(self):
		''' Turn the front wheels back straight '''
		if self._DEBUG:
			print self._DEBUG_INFO, "Turn straight"
		self.wheel.write(self._angle["straight"])

	def turn_right(self):
		''' Turn the front wheels right '''
		if self._DEBUG:
			print self._DEBUG_INFO, "Turn right"
		self.wheel.write(self._angle["right"])

	def turn(self, angle):
		''' Turn the front wheels to the giving angle '''
		if self._DEBUG:
			print self._DEBUG_INFO, "Turn to", angle
		if angle < self._angle["left"]:
			angle = self._angle["left"]
		if angle > self._angle["right"]:
			angle = self._angle["right"]
		self.wheel.write(angle)

	@property
	def channel(self):
		return self._channel
	@channel.setter
	def channel(self, chn):
		self._channel = chn

	@property
	def turning_max(self):
		return self._turning_max

	@turning_max.setter
	def turning_max(self, angle):
		self._turning_max = angle
		self._min_angle = self._straight_angle - angle
		self._max_angle = self._straight_angle + angle
		self._angle = {"left":self._min_angle, "straight":self._straight_angle, "right":self._max_angle}

	@property
	def turning_offset(self):
		return self._turning_offset

	@turning_offset.setter
	def turning_offset(self, value):
		if not isinstance(value, int):
			raise TypeError('"turning_offset" must be "int"')
		self._turning_offset = value
		self.db.set('turning_offset', value)
		self.wheel.offset = value
		self.turn_straight()

	@property
	def debug(self):
		return self._DEBUG
	@debug.setter
	def debug(self, debug):
		''' Set if debug information shows '''
		if debug in (True, False):
			self._DEBUG = debug
		else:
			raise ValueError('debug must be "True" (Set debug on) or "False" (Set debug off), not "{0}"'.format(debug))

		if self._DEBUG:
			print self._DEBUG_INFO, "Set debug on"
			print self._DEBUG_INFO, "Set wheel debug on"
			self.wheel.debug = True
		else:
			print self._DEBUG_INFO, "Set debug off"
			print self._DEBUG_INFO, "Set wheel debug off"
			self.wheel.debug = False

	def ready(self):
		''' Get the front wheels to the ready position. '''
		if self._DEBUG:
			print self._DEBUG_INFO, 'Turn to "Ready" position'
		self.wheel.offset = self.turning_offset
		self.turn_straight()

	def calibration(self):
		''' Get the front wheels to the calibration position. '''
		if self._DEBUG:
			print self._DEBUG_INFO, 'Turn to "Calibration" position'
		self.turn_straight()
		self.cali_turning_offset = self.turning_offset

	def cali_left(self):
		''' Calibrate the wheels to left '''
		self.cali_turning_offset -= 1
		self.wheel.offset = self.cali_turning_offset
		self.turn_straight()

	def cali_right(self):
		''' Calibrate the wheels to right '''
		self.cali_turning_offset += 1
		self.wheel.offset = self.cali_turning_offset
		self.turn_straight()

	def cali_ok(self):
		''' Save the calibration value '''
		self.turning_offset = self.cali_turning_offset
		self.db.set('turning_offset', self.turning_offset)

def test(chn=0):
	import time
	front_wheels = Front_Wheels(channel=chn)
	try:
		while True:
			print "turn_left"
			front_wheels.turn_left()
			time.sleep(1)
			print "turn_straight"
			front_wheels.turn_straight()
			time.sleep(1)
			print "turn_right"
			front_wheels.turn_right()
			time.sleep(1)
			print "turn_straight"
			front_wheels.turn_straight()
			time.sleep(1)
	except KeyboardInterrupt:
		front_wheels.turn_straight()

if __name__ == '__main__':
	test()