Simplified Adafruit Python SSD1306 for Raspberry Pi 3B+ (I2C only)

ssd1306.py

from __future__ import division
from smbus import SMBus


SSD1306_ADDRESS             = 0x3C

SSD1306_MEMORYMODE          = 0x20
SSD1306_COLUMNADDR          = 0x21
SSD1306_PAGEADDR            = 0x22
SSD1306_SETCONTRAST         = 0x81
SSD1306_CHARGEPUMP          = 0x8D
SSD1306_SEGREMAP            = 0xA0
SSD1306_DISPLAYALLON_RESUME = 0xA4
SSD1306_DISPLAYALLON        = 0xA5 #< Not currently used
SSD1306_NORMALDISPLAY       = 0xA6
SSD1306_INVERTDISPLAY       = 0xA7
SSD1306_SETMULTIPLEX        = 0xA8
SSD1306_DISPLAYOFF          = 0xAE
SSD1306_DISPLAYON           = 0xAF
SSD1306_COMSCANINC          = 0xC0 #< Not currently used
SSD1306_COMSCANDEC          = 0xC8
SSD1306_SETDISPLAYOFFSET    = 0xD3
SSD1306_SETDISPLAYCLOCKDIV  = 0xD5
SSD1306_SETPRECHARGE        = 0xD9
SSD1306_SETCOMPINS          = 0xDA
SSD1306_SETVCOMDETECT       = 0xDB

SSD1306_SETLOWCOLUMN        = 0x00 #< Not currently used
SSD1306_SETHIGHCOLUMN       = 0x10 #< Not currently used
SSD1306_SETSTARTLINE        = 0x40

SSD1306_EXTERNALVCC         = 0x01 #< External display voltage source
SSD1306_SWITCHCAPVCC        = 0x02 #< Gen. display voltage from 3.3V

SSD1306_RIGHT_HORIZONTAL_SCROLL              = 0x26 #< Init rt scroll
SSD1306_LEFT_HORIZONTAL_SCROLL               = 0x27 #< Init left scroll
SSD1306_VERTICAL_AND_RIGHT_HORIZONTAL_SCROLL = 0x29 #< Init diag scroll
SSD1306_VERTICAL_AND_LEFT_HORIZONTAL_SCROLL  = 0x2A #< Init diag scroll
SSD1306_DEACTIVATE_SCROLL                    = 0x2E #< Stop scroll
SSD1306_ACTIVATE_SCROLL                      = 0x2F #< Start scroll
SSD1306_SET_VERTICAL_SCROLL_AREA             = 0xA3 #< Set scroll range


class SSD1306(object):
    def __init__(self, width, height, address=SSD1306_ADDRESS):
        self.width = width
        self.height = height
        self.address = address

        self.bus = SMBus(1)
        self.pages = height//8
        self.clear()

    def command(self, values):
        try:
            iter(values)
        except TypeError:
            values = [values]
        finally:
            for value in values:
                self.bus.write_byte_data(self.address, 0x00, value)

    def data(self, value):
        try:
            iter(values)
        except TypeError:
            values = [values]
        finally:
            for value in values:
                self.bus.write_byte_data(self.address, 0x40, value)

    def begin(self, vccstate=SSD1306_SWITCHCAPVCC):
        self.vccstate = vccstate
        self.initialize()

    def display(self):
        self.command([
            SSD1306_PAGEADDR, 0x00, self.pages-1,
            SSD1306_COLUMNADDR, 0x00, self.width-1,
        ])
        for i in range(0, len(self.buffer), 16):
            self.bus.write_i2c_block_data(self.address, 0x40, self.buffer[i:i+16])

    def image(self, image):
        if image.mode=='1':
            imwidth, imheight = image.size
            if imwidth==self.width and imheight==self.height:
                pix = image.load()
                index = 0
                for page in range(self.pages):
                    for x in range(self.width):
                        bits = 0
                        for bit in [0,1,2,3,4,5,6,7]:
                            bits = bits << 1
                            bits |= 0 if pix[(x,page*8+7-bit)]==0 else 1
                        self.buffer[index] = bits
                        index += 1

    def clear(self):
        self.buffer = [0] * (self.width * self.pages)

    def set_contrast(self, contrast):
        self.command([
            SSD1306_SETCONTRAST, contrast,
        ])

    def initialize(self):
        self.command([
            SSD1306_DISPLAYOFF,
            SSD1306_SETDISPLAYCLOCKDIV, 0x80,
            SSD1306_SETMULTIPLEX, self.height-1,
        ])
        self.command([
            SSD1306_SETDISPLAYOFFSET, 0x00,
            SSD1306_SETSTARTLINE|0x00,
            SSD1306_CHARGEPUMP, 0x10 if self.vccstate==SSD1306_EXTERNALVCC else 0x14,
        ])
        self.command([
            SSD1306_MEMORYMODE, 0x00,
            SSD1306_SEGREMAP|0x01,
            SSD1306_COMSCANDEC,
        ])
        if self.width==128 and self.height==64:
            self.command([
                SSD1306_SETCOMPINS, 0x12,
                SSD1306_SETCONTRAST, 0x9F if self.vccstate==SSD1306_EXTERNALVCC else 0xCF,
            ])
        elif self.width==128 and self.height==32:
            self.command([
                SSD1306_SETCOMPINS, 0x02,
                SSD1306_SETCONTRAST, 0x8F,
            ])
        elif self.width==96 and self.height==16:
            self.command([
                SSD1306_SETCOMPINS, 0x02,
                SSD1306_SETCONTRAST, 0x10 if self.vccstate==SSD1306_EXTERNALVCC else 0xAF,
            ])
        else:
          # TODO: map other screens
          pass
        self.command([
            SSD1306_SETPRECHARGE, 0x22 if self.vccstate==SSD1306_EXTERNALVCC else 0xF1,
        ])
        self.command([
            SSD1306_SETVCOMDETECT, 0x40,
            SSD1306_DISPLAYALLON_RESUME, SSD1306_NORMALDISPLAY,
            SSD1306_DEACTIVATE_SCROLL,
            SSD1306_DISPLAYON,
        ])