FourDigit.py

from ._HT16K33 import Device


__all__ = ['FourDigit']


class FourDigit(Device):
  '''
     Four seven-segment digit LED display for Adafruit's HT16K33 I2C backpack
     - - -
     [Blue](http://adafruit.com/products/881)
     [Green](http://adafruit.com/products/880)
     [Red](http://adafruit.com/products/878)
     [Yellow](http://adafruit.com/products/879)
     [White](http://adafruit.com/products/1002)
  '''

  TOP_BAR          = 0x01
  MIDDLE_BAR       = 0x40
  BOTTOM_BAR       = 0x08
  LEFT_TOP_BAR     = 0x20
  LEFT_BOTTOM_BAR  = 0x10
  RIGHT_TOP_BAR    = 0x02
  RIGHT_BOTTOM_BAR = 0x04
  PERIOD           = 0x80

  DIGIT_ADDRESS = [0x00, 0x02, 0x06, 0x08]
  COLON_ADDRESS = 0x04

  CHARACTER_MAP = {
    0x30 : 0x3F, # 0
    0x31 : 0x06, # 1
    0x32 : 0x5B, # 2
    0x33 : 0x4F, # 3
    0x34 : 0x66, # 4
    0x35 : 0x6d, # 5
    0x36 : 0x7d, # 6
    0x37 : 0x07, # 7
    0x38 : 0x7F, # 8
    0x39 : 0x67  # 9
  }

  def alterSingleLED(self, position=0, new_byte=0x00, action=None):
    '''
       Manipulate single LED in character position
       - position (0..3)
       - new_byte (0..0xFF)
       - action   ("or","xor","andnot")

       Example:
       >>> digit = FourDigit().setUp()    # Set-up
       >>> digit.setDigit(0, 0x5B)            # Assign "2" character to first digit
       >>> digit.alterSingleLED(0, 0x80,"or") # Alter first digit to include period
    '''
    position=int(position) % 4
    digit_address = self.getDigitAddressAtPosition(position)
    byte = self.bus.read_byte_data(self.address, digit_address)
    if action == "or":
        byte |= new_byte
    elif action == "xor":
        byte ^= new_byte
    elif action == "andnot":
        byte &= ~new_byte
    else:
        byte = new_byte
    self.bus.write_byte_data(self.address, digit_address, byte)

  def getDigitAddressAtPosition(self, position=0):
    '''
      Retrive address by position
      - position (0..3) 

      Example:
      >>> digit = FourDigit()
      >>> digit.getDigitAddressAtPosition(1)
      2
    '''
    return self.DIGIT_ADDRESS[int(position) % len(self.DIGIT_ADDRESS)]

  def chrToInt(self, character):
    '''
       Convert character to LED display integer

       Each available character will have the LED display
       integer assigned to the CHARACTER_MAP key matching
       character's order. Any character not present in 
       CHARACTER_MAP will return 0x00 (clear LED integer.)

       - character (see CHARACTER_MAP)

       Example:
       >>> digit = FourDigit().setUp()
       >>> digit.chrToInt(8)
       127
       >>> digit.chrToInt("T")
       0
    '''
    integer=0x00
    try:
      integer=self.CHARACTER_MAP[ord(str(character))]
    except KeyError:
      pass
    return integer

  def readAtPosition(self, position=0):
    '''
       Return LED value currently in devices EEPROM
       - position (0..3)

       Example:
       >>> digit = FourDigit().setUp()
       >>> digit.setDigit(0, 0xFF)
       >>> digit.readAtPosition(0)
       255
    '''
    return self.bus.read_byte_data(self.address, self.getDigitAddressAtPosition(position))

  def setDigit(self, position=0, value=0x00):
    '''
       Assign LED display to digit
       - position
       - value

       Example:
       >>> digit = FourDigit().setUp()
       >>> digit.setDigit(0, 0x06) # 1
       >>> digit.setDigit(1, 0x5B) # 2
       >>> digit.setDigit(2, 0x4F) # 3
       >>> digit.setDigit(3, 0x66) # 4
    '''
    self.bus.write_byte_data(self.address, self.getDigitAddressAtPosition(position), int(value) % 0x100)

  def turnOnColon(self):
    '''
       Enable colon symbol

       Example:
       >>> digit = FourDigit().setUp()
       >>> digit.turnOnColon()
    '''
    self.bus.write_byte_data(self.address, self.COLON_ADDRESS, 0xFF)

  def turnOffColon(self):
    '''
       Disable colon symbol

       Example:
       >>> digit = FourDigit().setUp()
       >>> digit.turnOffColon()
    '''
    self.bus.write_byte_data(self.address, self.COLON_ADDRESS, 0x00)

  def turnOnPeriodAtPosition(self, position=0):
    '''
       Enable period symbol at given position
    '''
    self.alterSingleLED(position, self.PERIOD,"or")

  def turnOffPeriodAtPosition(self, position=0):
    '''
       Disable period symbol at given position
    '''
    self.alterSingleLED(position, self.PERIOD,"andnot")

  def writeDigit(self, position, char=None):
    '''
       Write single character to a given position

       Example:
       >>> digit = FourDigit().setUp()
       >>> for i in range(4):
       ...   digit.writeDigit(i, i)
    '''
    self.setDigit(position, self.chrToInt(char))

if __name__ == "__main__":
    import doctest
    doctest.testmod()