stdd/adafruit_7segment/Adafruit_LEDBackpack.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

import time
from copy import copy
from Adafruit_I2C import Adafruit_I2C

# ============================================================================
# LEDBackpack Class
# ============================================================================


class LEDBackpack:
    i2c = None

    # Registers
    __HT16K33_REGISTER_DISPLAY_SETUP = 0x80
    __HT16K33_REGISTER_SYSTEM_SETUP = 0x20
    __HT16K33_REGISTER_DIMMING = 0xE0

    # Blink rate
    __HT16K33_BLINKRATE_OFF = 0x00
    __HT16K33_BLINKRATE_2HZ = 0x01
    __HT16K33_BLINKRATE_1HZ = 0x02
    __HT16K33_BLINKRATE_HALFHZ = 0x03

    # Display buffer (8x16-bits)
    __buffer = [0x0000, 0x0000, 0x0000, 0x0000,
                0x0000, 0x0000, 0x0000, 0x0000]

    # Constructor
    def __init__(self, address=0x70, debug=False):
        self.i2c = Adafruit_I2C(address)
        self.address = address
        self.debug = debug

        # Turn the oscillator on
        self.i2c.write8(self.__HT16K33_REGISTER_SYSTEM_SETUP | 0x01, 0x00)

        # Turn blink off
        self.setBlinkRate(self.__HT16K33_BLINKRATE_OFF)

        # Set maximum brightness
        self.setBrightness(15)

        # Clear the screen
        self.clear()

    def setBrightness(self, brightness):
        "Sets the brightness level from 0..15"
        if (brightness > 15):
            brightness = 15
        self.i2c.write8(self.__HT16K33_REGISTER_DIMMING | brightness, 0x00)

    def setBlinkRate(self, blinkRate):
        "Sets the blink rate"
        if (blinkRate > self.__HT16K33_BLINKRATE_HALFHZ):
            blinkRate = self.__HT16K33_BLINKRATE_OFF
        self.i2c.write8(self.__HT16K33_REGISTER_DISPLAY_SETUP | 0x01
                        | (blinkRate << 1), 0x00)

    def setBufferRow(self, row, value, update=True):
        "Updates a single 16-bit entry in the 8*16-bit buffer"
        if (row > 7):
            return                    # Prevent buffer overflow
        self.__buffer[row] = value  # value # & 0xFFFF
        if (update):
            self.writeDisplay()       # Update the display

    def getBuffer(self):
        "Returns a copy of the raw buffer contents"
        bufferCopy = copy(self.__buffer)
        return bufferCopy

    def writeDisplay(self):
        "Updates the display memory"
        bytes = []
        for item in self.__buffer:
            bytes.append(item & 0xFF)
            bytes.append((item >> 8) & 0xFF)
        self.i2c.writeList(0x00, bytes)

    def clear(self, update=True):
        "Clears the display memory"
        self.__buffer = [0, 0, 0, 0, 0, 0, 0, 0]
        if (update):
            self.writeDisplay()

led = LEDBackpack(0x70)