上文中的代码通过wiringPi的API调用devfs API来显示图片。 这里分析的Python代码也通过类似的方法来显示图片。
主要用到了两个Library.
import spidev
import RPi.GPIO as GPIORPi.GPIO
在 https://blog.csdn.net/feiwatson/article/details/80790340 大致分析了RPi.GPIO.
这里的oled代码用到了RPi.GPIO 来控制 D/C 和 RST 两个GPIO。
spidev
https://pypi.org/project/spidev/
这里其实和wiringPi的代码类似，最终还是通过devfs API来调用底层SPI驱动
代码
ssd1306 的initialize， display
import spidev
import RPi.GPIO as GPIO
import time
# Constants
SSD1306_SETCONTRAST = 0x81
SSD1306_DISPLAYALLON_RESUME = 0xA4
SSD1306_DISPLAYALLON = 0xA5
SSD1306_NORMALDISPLAY = 0xA6
SSD1306_INVERTDISPLAY = 0xA7
SSD1306_DISPLAYOFF = 0xAE
SSD1306_DISPLAYON = 0xAF
SSD1306_SETDISPLAYOFFSET = 0xD3
SSD1306_SETCOMPINS = 0xDA
SSD1306_SETVCOMDETECT = 0xDB
SSD1306_SETDISPLAYCLOCKDIV = 0xD5
SSD1306_SETPRECHARGE = 0xD9
SSD1306_SETMULTIPLEX = 0xA8
SSD1306_SETLOWCOLUMN = 0x00
SSD1306_SETHIGHCOLUMN = 0x10
SSD1306_SETSTARTLINE = 0x40
SSD1306_MEMORYMODE = 0x20
SSD1306_COLUMNADDR = 0x21
SSD1306_PAGEADDR = 0x22
SSD1306_COMSCANINC = 0xC0
SSD1306_COMSCANDEC = 0xC8
SSD1306_SEGREMAP = 0xA0
SSD1306_CHARGEPUMP = 0x8D
SSD1306_EXTERNALVCC = 0x1
SSD1306_SWITCHCAPVCC = 0x2
# Scrolling constants
SSD1306_ACTIVATE_SCROLL = 0x2F
SSD1306_DEACTIVATE_SCROLL = 0x2E
SSD1306_SET_VERTICAL_SCROLL_AREA = 0xA3
SSD1306_RIGHT_HORIZONTAL_SCROLL = 0x26
SSD1306_LEFT_HORIZONTAL_SCROLL = 0x27
SSD1306_VERTICAL_AND_RIGHT_HORIZONTAL_SCROLL = 0x29
SSD1306_VERTICAL_AND_LEFT_HORIZONTAL_SCROLL = 0x2A
class SSD1306(object):
"""class for SSD1306 128*64 0.96inch OLED displays."""
def __init__(self,rst,dc,spi):
self.width = 128
self.height = 64
self._pages = 8
self._buffer = [0]*(self.width*self._pages)
#Initialize DC RST pin
self._dc = dc
self._rst = rst
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)
GPIO.setup(self._dc,GPIO.OUT)
GPIO.setup(self._rst,GPIO.OUT)
#Initialize SPI
self._spi = spi
def command(self,cmd):
"""Send command byte to display"""
GPIO.output(self._dc,GPIO.LOW)
self._spi.writebytes([cmd])
def data(self,val):
"""Send byte of data to display"""
GPIO.output(self._dc,GPIO.HIGHT)
self._spi.writebytes([val])
def begin(self,vccstate=SSD1306_SWITCHCAPVCC):
"""Initialize dispaly"""
self._vccstate = vccstate
self.reset()
self.command(SSD1306_DISPLAYOFF) # 0xAE
self.command(SSD1306_SETDISPLAYCLOCKDIV) # 0xD5
self.command(0x80) # the suggested ra tio 0x80
self.command(SSD1306_SETMULTIPLEX) # 0xA8
self.command(0x3F)
self.command(SSD1306_SETDISPLAYOFFSET) # 0xD3
self.command(0x0) # no offset
self.command(SSD1306_SETSTARTLINE | 0x0) # line #0
self.command(SSD1306_CHARGEPUMP) # 0x8D
if self._vccstate == SSD1306_EXTERNALVCC:
self.command(0x10)
else:
self.command(0x14)
self.command(SSD1306_MEMORYMODE) # 0x20
self.command(0x00) # 0x0 act like ks0108
self.command(SSD1306_SEGREMAP | 0x1)
self.command(SSD1306_COMSCANDEC)
self.command(SSD1306_SETCOMPINS) # 0xDA
self.command(0x12)
self.command(SSD1306_SETCONTRAST) # 0x81
if self._vccstate == SSD1306_EXTERNALVCC:
self.command(0x9F)
else:
self.command(0xCF)
self.command(SSD1306_SETPRECHARGE) # 0xd9
if self._vccstate == SSD1306_EXTERNALVCC:
self.command(0x22)
else:
self.command(0xF1)
self.command(SSD1306_SETVCOMDETECT) # 0xDB
self.command(0x40)
self.command(SSD1306_DISPLAYALLON_RESUME) # 0xA4
self.command(SSD1306_NORMALDISPLAY) # 0xA6
self.command(SSD1306_DISPLAYON)
def reset(self):
"""Reset the display"""
GPIO.output(self._rst,GPIO.HIGH)
time.sleep(0.001)
GPIO.output(self._rst,GPIO.LOW)
time.sleep(0.010)
GPIO.output(self._rst,GPIO.HIGH)
def display(self):
"""Write display buffer to physical display"""
self.command(SSD1306_COLUMNADDR)
self.command(0) #Cloumn start address
self.command(self.width-1) #Cloumn end address
self.command(SSD1306_PAGEADDR)
self.command(0) #Page start address
self.command(self._pages-1) #Page end address
#Write buffer data
GPIO.output(self._dc,GPIO.HIGH)
self._spi.writebytes(self._buffer)
def image(self, image):
"""Set buffer to value of Python Imaging Library image."""
if image.mode != '1':
raise ValueError('Image must be in mode 1.')
imwidth, imheight = image.size
if imwidth != self.width or imheight != self.height:
raise ValueError('Image must be same dimensions as display \
({0}x{1}).' .format(self.width, self.height))
pix = image.load()
# Iterate through the memory pages
index = 0
for page in range(self._pages):
# Iterate through all x axis columns.
for x in range(self.width):
# Set the bits for the column of pixels at the current position.
bits = 0
# Don't use range here as it's a bit slow
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
# Update buffer byte and increment to next byte.
self._buffer[index] = bits
index += 1
def clear(self):
"""Clear contents of image buffer"""
self._buffer = [0]*(self.width*self._pages)
def set_contrast(self, contrast):
"""Sets the contrast of the display.
Contrast should be a value between 0 and 255."""
if contrast < 0 or contrast > 255:
raise ValueError('Contrast must be a value from 0 to 255).')
self.command(SSD1306_SETCONTRAST)
self.command(contrast)
def dim(self, dim):
"""Adjusts contrast to dim the display if dim is True,
otherwise sets the contrast to normal brightness if dim is False."""
# Assume dim display.
contrast = 0
# Adjust contrast based on VCC if not dimming.
if not dim:
if self._vccstate == SSD1306_EXTERNALVCC:
contrast = 0x9F
else:
contrast = 0xCF
显示一个图片到oled
# Copyright (c) 2015 WaveShare
# Author: My MX
import time
import spidev as SPI
import SSD1306
import Image
# Raspberry Pi pin configuration:
RST = 19
DC = 16
bus = 0
device = 0
# 128x32 display with hardware I2C:
disp = SSD1306.SSD1306(rst=RST,dc=DC,spi=SPI.SpiDev(bus,device))
# Initialize library.
disp.begin()
# Clear display.
disp.clear()
disp.display()
# Load image based on OLED display height. Note that image is converted to 1 bit color.
image = Image.open('happycat.ppm').convert('1')
# Alternatively load a different format image, resize it, and convert to 1 bit color.
#image = Image.open('happycat.png').resize((disp.width, disp.height), Image.ANTIALIAS).convert('1')
# Display image.
disp.image(image)
disp.display()
