stdd/adafruit_7segment/sevensegment.py

# -*- coding: utf-8-*-
#
# This file is part of stdd, the simple time display daemon,
# written by Helmut Pozimski <helmut@pozimski.eu>,
# licensed under the 3-clause BSD license
# This file was originally written by Written by Limor Fried, Kevin Townsend
# and Mikey Sklar for Adafruit Industries. BSD license,
# all text above must be included in any redistribution

"""
===========================================================================
 7-Segment Display
===========================================================================

 This class is meant to be used with the four-character, seven segment
 displays available from Adafruit.
"""


from __future__ import print_function
from adafruit_7segment.ledbackpack import LEDBackpack


class SevenSegment(object):
    """This class represents the seven segment display and allows to access and
    write data to it.
    """
    disp = None

    # Hexadecimal character lookup table (row 1 = 0..9, row 2 = A..F)
    digits = [0x3F, 0x06, 0x5B, 0x4F, 0x66, 0x6D, 0x7D, 0x07, 0x7F, 0x6F,
              0x77, 0x7C, 0x39, 0x5E, 0x79, 0x71]

    # Constructor
    def __init__(self, address=0x70, debug=False):
        if debug:
            print("Initializing a new instance of LEDBackpack at \
            0x%02X" % address)
        self.disp = LEDBackpack(address=address, debug=debug)

    def write_digit_raw(self, char_number, value):
        """Sets a digit using the raw 16-bit value"""
        if char_number > 7:
            return
        # Set the appropriate digit
        self.disp.set_buffer_row(char_number, value)

    def write_digit(self, char_number, value, dot=False):
        """Sets a single decimal or hexademical value (0..9 and A..F)"""
        if char_number > 7:
            return
        if value > 0xF:
            return
        # Set the appropriate digit
        self.disp.set_buffer_row(char_number, self.digits[value] | (dot << 7))

    def set_colon(self, state=True):
        """Enables or disables the colon character"""
        # Warning: This function assumes that the colon is character '2',
        # which is the case on 4 char displays, but may need to be modified
        # if another display type is used
        if state:
            self.disp.set_buffer_row(2, 0xFFFF)
        else:
            self.disp.set_buffer_row(2, 0)

    def set_brightness(self, brightness):
        """ Sets the brightness. """
        self.disp.set_brightness(brightness)