I2C driver for micropython esp8266 ssd1306 OLED (ssd1306a.py is paired down and works with the font.py file to allowing generating text)

font.py

# Originally from https://github.com/guyc/py-gaugette/blob/master/gaugette/font5x8.py
# Contains ASCII 32 (space) through ASCII 90 (Z)

cols = 5
rows = 8
bytes = [
    0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x5F, 0x00, 0x00,
    0x00, 0x07, 0x00, 0x07, 0x00,
    0x14, 0x7F, 0x14, 0x7F, 0x14,
    0x24, 0x2A, 0x7F, 0x2A, 0x12,
    0x23, 0x13, 0x08, 0x64, 0x62,
    0x36, 0x49, 0x56, 0x20, 0x50,
    0x00, 0x08, 0x07, 0x03, 0x00,
    0x00, 0x1C, 0x22, 0x41, 0x00,
    0x00, 0x41, 0x22, 0x1C, 0x00,
    0x2A, 0x1C, 0x7F, 0x1C, 0x2A,
    0x08, 0x08, 0x3E, 0x08, 0x08,
    0x00, 0x80, 0x70, 0x30, 0x00,
    0x08, 0x08, 0x08, 0x08, 0x08,
    0x00, 0x00, 0x60, 0x60, 0x00,
    0x20, 0x10, 0x08, 0x04, 0x02,
    0x3E, 0x51, 0x49, 0x45, 0x3E,
    0x00, 0x42, 0x7F, 0x40, 0x00,
    0x72, 0x49, 0x49, 0x49, 0x46,
    0x21, 0x41, 0x49, 0x4D, 0x33,
    0x18, 0x14, 0x12, 0x7F, 0x10,
    0x27, 0x45, 0x45, 0x45, 0x39,
    0x3C, 0x4A, 0x49, 0x49, 0x31,
    0x41, 0x21, 0x11, 0x09, 0x07,
    0x36, 0x49, 0x49, 0x49, 0x36,
    0x46, 0x49, 0x49, 0x29, 0x1E,
    0x00, 0x00, 0x14, 0x00, 0x00,
    0x00, 0x40, 0x34, 0x00, 0x00,
    0x00, 0x08, 0x14, 0x22, 0x41,
    0x14, 0x14, 0x14, 0x14, 0x14,
    0x00, 0x41, 0x22, 0x14, 0x08,
    0x02, 0x01, 0x59, 0x09, 0x06,
    0x3E, 0x41, 0x5D, 0x59, 0x4E,
    0x7C, 0x12, 0x11, 0x12, 0x7C,
    0x7F, 0x49, 0x49, 0x49, 0x36,
    0x3E, 0x41, 0x41, 0x41, 0x22,
    0x7F, 0x41, 0x41, 0x41, 0x3E,
    0x7F, 0x49, 0x49, 0x49, 0x41,
    0x7F, 0x09, 0x09, 0x09, 0x01,
    0x3E, 0x41, 0x41, 0x51, 0x73,
    0x7F, 0x08, 0x08, 0x08, 0x7F,
    0x00, 0x41, 0x7F, 0x41, 0x00,
    0x20, 0x40, 0x41, 0x3F, 0x01,
    0x7F, 0x08, 0x14, 0x22, 0x41,
    0x7F, 0x40, 0x40, 0x40, 0x40,
    0x7F, 0x02, 0x1C, 0x02, 0x7F,
    0x7F, 0x04, 0x08, 0x10, 0x7F,
    0x3E, 0x41, 0x41, 0x41, 0x3E,
    0x7F, 0x09, 0x09, 0x09, 0x06,
    0x3E, 0x41, 0x51, 0x21, 0x5E,
    0x7F, 0x09, 0x19, 0x29, 0x46,
    0x26, 0x49, 0x49, 0x49, 0x32,
    0x03, 0x01, 0x7F, 0x01, 0x03,
    0x3F, 0x40, 0x40, 0x40, 0x3F,
    0x1F, 0x20, 0x40, 0x20, 0x1F,
    0x3F, 0x40, 0x38, 0x40, 0x3F,
    0x63, 0x14, 0x08, 0x14, 0x63,
    0x03, 0x04, 0x78, 0x04, 0x03,
    0x61, 0x59, 0x49, 0x4D, 0x43]

ssd1306.py

# The MIT License (MIT)
# 
# Based on Kenneth Henderick's Micropython drivers: https://github.com/khenderick/micropython-drivers
# Copyright (c) 2014 Kenneth Henderick
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

from time import sleep_ms
from machine import Pin, I2C

# Constants
DISPLAYOFF          = 0xAE
SETCONTRAST         = 0x81
DISPLAYALLON_RESUME = 0xA4
DISPLAYALLON        = 0xA5
NORMALDISPLAY       = 0xA6
INVERTDISPLAY       = 0xA7
DISPLAYON           = 0xAF
SETDISPLAYOFFSET    = 0xD3
SETCOMPINS          = 0xDA
SETVCOMDETECT       = 0xDB
SETDISPLAYCLOCKDIV  = 0xD5
SETPRECHARGE        = 0xD9
SETMULTIPLEX        = 0xA8
SETLOWCOLUMN        = 0x00
SETHIGHCOLUMN       = 0x10
SETSTARTLINE        = 0x40
MEMORYMODE          = 0x20
COLUMNADDR          = 0x21
PAGEADDR            = 0x22
COMSCANINC          = 0xC0
COMSCANDEC          = 0xC8
SEGREMAP            = 0xA0
CHARGEPUMP          = 0x8D
EXTERNALVCC         = 0x10
SWITCHCAPVCC        = 0x20
SETPAGEADDR         = 0xB0
SETCOLADDR_LOW      = 0x00
SETCOLADDR_HIGH     = 0x10
ACTIVATE_SCROLL                      = 0x2F
DEACTIVATE_SCROLL                    = 0x2E
SET_VERTICAL_SCROLL_AREA             = 0xA3
RIGHT_HORIZONTAL_SCROLL              = 0x26
LEFT_HORIZONTAL_SCROLL               = 0x27
VERTICAL_AND_RIGHT_HORIZONTAL_SCROLL = 0x29
VERTICAL_AND_LEFT_HORIZONTAL_SCROLL  = 0x2A

# I2C devices are accessed through a Device ID. This is a 7-bit
# value but is sometimes expressed left-shifted by 1 as an 8-bit value.
# A pin on SSD1306 allows it to respond to ID 0x3C or 0x3D. The board
# I bought from ebay used a 0-ohm resistor to select between "0x78"
# (0x3c << 1) or "0x7a" (0x3d << 1). The default was set to "0x78"
DEVID = 0x3c

# I2C communication here is either <DEVID> <CTL_CMD> <command byte>
# or <DEVID> <CTL_DAT> <display buffer bytes> <> <> <> <>...
# These two values encode the Co (Continuation) bit as b7 and the
# D/C# (Data/Command Selection) bit as b6.
CTL_CMD = 0x80
CTL_DAT = 0x40

class SSD1306(object):

  def __init__(self, height=32, external_vcc=True, i2c_devid=DEVID):
    self.external_vcc = external_vcc
    self.height       = 32 if height == 32 else 64
    self.pages        = int(self.height / 8)
    self.columns      = 128

    self.devid = i2c_devid
    self.offset = 1
    self.cbuffer = bytearray(2)
    self.cbuffer[0] = CTL_CMD

    self.i2c = I2C(scl=Pin(5), sda=Pin(4), freq=400000) 

  def clear(self):
    self.buffer = bytearray(self.offset + self.pages * self.columns)
    if self.offset == 1:
      self.buffer[0] = CTL_DAT

  def write_command(self, command_byte):
    self.cbuffer[1] = command_byte
    self.i2c.writeto(self.devid, self.cbuffer)

  def invert_display(self, invert):
    self.write_command(INVERTDISPLAY if invert else NORMALDISPLAY)

  def display(self):
    self.write_command(COLUMNADDR)
    self.write_command(0)
    self.write_command(self.columns - 1)
    self.write_command(PAGEADDR)
    self.write_command(0)
    self.write_command(self.pages - 1)
    self.i2c.writeto(self.devid, self.buffer)

  def set_pixel(self, x, y, state):
    index = x + (int(y / 8) * self.columns)
    if state:
      self.buffer[self.offset + index] |= (1 << (y & 7))
    else:
      self.buffer[self.offset + index] &= ~(1 << (y & 7))

  def init_display(self):
    chargepump = 0x10 if self.external_vcc else 0x14
    precharge  = 0x22 if self.external_vcc else 0xf1
    multiplex  = 0x1f if self.height == 32 else 0x3f
    compins    = 0x02 if self.height == 32 else 0x12
    contrast   = 0xff # 0x8f if self.height == 32 else (0x9f if self.external_vcc else 0x9f)
    data = [DISPLAYOFF,
            SETDISPLAYCLOCKDIV, 0x80,
            SETMULTIPLEX, multiplex,
            SETDISPLAYOFFSET, 0x00,
            SETSTARTLINE | 0x00,
            CHARGEPUMP, chargepump,
            MEMORYMODE, 0x00,
            SEGREMAP | 0x10,
            COMSCANDEC,
            SETCOMPINS, compins,
            SETCONTRAST, contrast,
            SETPRECHARGE, precharge,
            SETVCOMDETECT, 0x40,
            DISPLAYALLON_RESUME,
            NORMALDISPLAY,
            DISPLAYON]
    for item in data:
      self.write_command(item)
    self.clear()
    self.display()

  def poweron(self):
    if self.offset == 1:
      sleep_ms(10)
    else:
      self.res.high()
      sleep_ms(1)
      self.res.low()
      sleep_ms(10)
      self.res.high()
      sleep_ms(10)

  def poweroff(self):
    self.write_command(DISPLAYOFF)

  def contrast(self, contrast):
    self.write_command(SETCONTRAST)
    self.write_command(contrast)

  def set_start_end_cols(self, start_col=0, end_col=None):
    if end_col is None:
      end_col = self.columns - 1
    if start_col < 0 or start_col > self.columns - 1:
      raise ValueError('Start column must be between 0 and %d.' % (self.columns - 1,))
    if end_col < start_col or end_col > self.columns -1:
      raise ValueError('End column must be between the start column (%d) and %d.' % (start_col, self.columns - 1))

    self.write_command(COLUMNADDR)
    self.write_command(start_col)  # Start column
    self.write_command(end_col)  # End column

  def set_start_end_pages(self, start_page=0, end_page=None):
    if end_page is None:
      end_page = self.pages - 1
    if start_page < 0 or start_page > self.pages - 1:
      raise ValueError('Start page must be between 0 and %d.' % (self.pages - 1,))
    if end_page < start_page or end_page > self.pages - 1:
      raise ValueError('End page must be between the start page (%d) and %d.' % (start_page, self.pages - 1))

    self.write_command(PAGEADDR)
    self.write_command(start_page)  # Page start address. (0 = reset)
    self.write_command(end_page)  # Page end address.

ssd1306a.py

# The MIT License (MIT)
# 
# Based on Kenneth Henderick's Micropython drivers: https://github.com/khenderick/micropython-drivers
# Copyright (c) 2014 Kenneth Henderick
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

from machine import Pin, I2C
import font

# Constants
DISPLAYOFF          = 0xAE
SETCONTRAST         = 0x81
DISPLAYALLON_RESUME = 0xA4
DISPLAYALLON        = 0xA5
NORMALDISPLAY       = 0xA6
INVERTDISPLAY       = 0xA7
DISPLAYON           = 0xAF
SETDISPLAYOFFSET    = 0xD3
SETCOMPINS          = 0xDA
SETVCOMDETECT       = 0xDB
SETDISPLAYCLOCKDIV  = 0xD5
SETPRECHARGE        = 0xD9
SETMULTIPLEX        = 0xA8
SETLOWCOLUMN        = 0x00
SETHIGHCOLUMN       = 0x10
SETSTARTLINE        = 0x40
MEMORYMODE          = 0x20
COLUMNADDR          = 0x21
PAGEADDR            = 0x22
COMSCANINC          = 0xC0
COMSCANDEC          = 0xC8
SEGREMAP            = 0xA0
CHARGEPUMP          = 0x8D
EXTERNALVCC         = 0x10
SWITCHCAPVCC        = 0x20
SETPAGEADDR         = 0xB0
SETCOLADDR_LOW      = 0x00
SETCOLADDR_HIGH     = 0x10
ACTIVATE_SCROLL                      = 0x2F
DEACTIVATE_SCROLL                    = 0x2E
SET_VERTICAL_SCROLL_AREA             = 0xA3
RIGHT_HORIZONTAL_SCROLL              = 0x26
LEFT_HORIZONTAL_SCROLL               = 0x27
VERTICAL_AND_RIGHT_HORIZONTAL_SCROLL = 0x29
VERTICAL_AND_LEFT_HORIZONTAL_SCROLL  = 0x2A

class SSD1306(object):

  def __init__(self):
    # assumes height=32, pages=4, columns=128, internal vcc

    self.cbuffer = bytearray(2)
    self.cbuffer[0] = 0x80

    self.i2c = I2C(scl=Pin(5), sda=Pin(4), freq=400000) 

  def clear(self):
    self.buffer = bytearray(513)
    self.buffer[0] = 0x40

  def write_command(self, command_byte):
    self.cbuffer[1] = command_byte
    self.i2c.writeto(0x3c, self.cbuffer)

  def invert_display(self, invert):
    self.write_command(INVERTDISPLAY if invert else NORMALDISPLAY)

  def display(self):
    self.write_command(COLUMNADDR)
    self.write_command(0)
    self.write_command(127) #(self.columns - 1)
    self.write_command(PAGEADDR)
    self.write_command(0)
    self.write_command(3) #(self.pages - 1)
    self.i2c.writeto(0x3c, self.buffer)

  def set_pixel(self, x, y, state):
    index = x + (int(y / 8) * 128)
    if state:
      self.buffer[1 + index] |= (1 << (y & 7))
    else:
      self.buffer[1 + index] &= ~(1 << (y & 7))

  def init_display(self):
    chargepump = 0x14
    precharge  = 0xf1
    multiplex  = 0x1f 
    compins    = 0x02 
    contrast   = 0xff # 0x8f if self.height == 32 else (0x9f if self.external_vcc else 0x9f)
    data = [DISPLAYOFF,
            SETDISPLAYCLOCKDIV, 0x80,
            SETMULTIPLEX, multiplex,
            SETDISPLAYOFFSET, 0x00,
            SETSTARTLINE | 0x00,
            CHARGEPUMP, chargepump,
            MEMORYMODE, 0x00,
            SEGREMAP | 0x10,
            COMSCANDEC,
            SETCOMPINS, compins,
            SETCONTRAST, contrast,
            SETPRECHARGE, precharge,
            SETVCOMDETECT, 0x40,
            DISPLAYALLON_RESUME,
            NORMALDISPLAY,
            DISPLAYON]
    for item in data:
      self.write_command(item)
    self.clear()
    self.display()

  def poweron(self):
    pass

  def poweroff(self):
    self.write_command(DISPLAYOFF)

  def contrast(self, contrast):
    self.write_command(SETCONTRAST)
    self.write_command(contrast)

  def draw_text(self, x, y, string, size=1, space=1):
    def pixel_x(char_number, char_column, point_row):
      char_offset = x + char_number * size * font.cols + space * char_number
      pixel_offset = char_offset + char_column * size + point_row
      return 128 - pixel_offset

    def pixel_y(char_row, point_column):
      char_offset = y + char_row * size
      return char_offset + point_column

    def pixel_mask(char, char_column, char_row):
      #char_index_offset = ord(char) * font.cols #original
      char_index_offset = (ord(char)-32) * font.cols
      return font.bytes[char_index_offset + char_column] >> char_row & 0x1

    pixels = (
      (pixel_x(char_number, char_column, point_row),
       pixel_y(char_row, point_column),
       pixel_mask(char, char_column, char_row))
      for char_number, char in enumerate(string)
      for char_column in range(font.cols)
      for char_row in range(font.rows)
      for point_column in range(size)
      for point_row in range(1, size + 1))

    for pixel in pixels:
      self.set_pixel(*pixel)