文章目录
- I2C通信
- OLED屏
- 接线
- SSD1306库
- I2C使用方法
- 查找OLEDI2C地址
- 主函数代码
- 显示动态数值
- 效果展示
I2C通信
I2C通信是一种单片机常用的通信协议，它具有一根总线设计，具有一个主机，可以挂载多个设备在总线上作为从机，主机通过选定不同的发送地址来发送内容给不同的从机。
OLED屏
采用具有4针脚的，支持I2C通信的OLED屏，大小为0.96寸的单色小屏，像素数为128x64。
接线
使用X9、X10引脚
PYB | OLED |
VCC | 3.3V |
GND | GND |
X9 | SCL |
X10 | SDA |
SSD1306库
ssd1306.py
# MicroPython SSD1306 OLED driver, I2C and SPI interfaces
import time
import framebuf
# register definitions
SET_CONTRAST = const(0x81)
SET_ENTIRE_ON = const(0xa4)
SET_NORM_INV = const(0xa6)
SET_DISP = const(0xae)
SET_MEM_ADDR = const(0x20)
SET_COL_ADDR = const(0x21)
SET_PAGE_ADDR = const(0x22)
SET_DISP_START_LINE = const(0x40)
SET_SEG_REMAP = const(0xa0)
SET_MUX_RATIO = const(0xa8)
SET_COM_OUT_DIR = const(0xc0)
SET_DISP_OFFSET = const(0xd3)
SET_COM_PIN_CFG = const(0xda)
SET_DISP_CLK_DIV = const(0xd5)
SET_PRECHARGE = const(0xd9)
SET_VCOM_DESEL = const(0xdb)
SET_CHARGE_PUMP = const(0x8d)
class SSD1306:
def __init__(self, width, height, external_vcc):
self.width = width
self.height = height
self.external_vcc = external_vcc
self.pages = self.height // 8
# Note the subclass must initialize self.framebuf to a framebuffer.
# This is necessary because the underlying data buffer is different
# between I2C and SPI implementations (I2C needs an extra byte).
self.poweron()
self.init_display()
def init_display(self):
for cmd in (
SET_DISP | 0x00, # off
# address setting
SET_MEM_ADDR, 0x00, # horizontal
# resolution and layout
SET_DISP_START_LINE | 0x00,
SET_SEG_REMAP | 0x01, # column addr 127 mapped to SEG0
SET_MUX_RATIO, self.height - 1,
SET_COM_OUT_DIR | 0x08, # scan from COM[N] to COM0
SET_DISP_OFFSET, 0x00,
SET_COM_PIN_CFG, 0x02 if self.height == 32 else 0x12,
# timing and driving scheme
SET_DISP_CLK_DIV, 0x80,
SET_PRECHARGE, 0x22 if self.external_vcc else 0xf1,
SET_VCOM_DESEL, 0x30, # 0.83*Vcc
# display
SET_CONTRAST, 0xff, # maximum
SET_ENTIRE_ON, # output follows RAM contents
SET_NORM_INV, # not inverted
# charge pump
SET_CHARGE_PUMP, 0x10 if self.external_vcc else 0x14,
SET_DISP | 0x01): # on
self.write_cmd(cmd)
self.fill(0)
self.show()
def poweroff(self):
self.write_cmd(SET_DISP | 0x00)
def contrast(self, contrast):
self.write_cmd(SET_CONTRAST)
self.write_cmd(contrast)
#翻转颜色
def invert(self, invert):
self.write_cmd(SET_NORM_INV | (invert & 1))
def show(self):
x0 = 0
x1 = self.width - 1
if self.width == 64:
# displays with width of 64 pixels are shifted by 32
x0 += 32
x1 += 32
self.write_cmd(SET_COL_ADDR)
self.write_cmd(x0)
self.write_cmd(x1)
self.write_cmd(SET_PAGE_ADDR)
self.write_cmd(0)
self.write_cmd(self.pages - 1)
self.write_framebuf()
#填充画面 0为空 1为亮
def fill(self, col):
self.framebuf.fill(col)
#填充一个像素在X,YE
def pixel(self, x, y, col):
self.framebuf.pixel(x, y, col)
#滚动
def scroll(self, dx, dy):
self.framebuf.scroll(dx, dy)
#文本
def text(self, string, x, y, col=1):
self.framebuf.text(string, x, y, col)
def hline(self, x, y, w, col=1):
self.framebuf.hline(x, y, w, col)
class SSD1306_I2C(SSD1306):
def __init__(self, width, height, i2c, addr=60, external_vcc=False):
self.i2c = i2c
self.addr = addr
self.temp = bytearray(2)
# Add an extra byte to the data buffer to hold an I2C data/command byte
# to use hardware-compatible I2C transactions. A memoryview of the
# buffer is used to mask this byte from the framebuffer operations
# (without a major memory hit as memoryview doesn't copy to a separate
# buffer).
self.buffer = bytearray(((height // 8) * width) + 1)
self.buffer[0] = 0x40 # Set first byte of data buffer to Co=0, D/C=1
self.framebuf = framebuf.FrameBuffer1(memoryview(self.buffer)[1:], width, height)
super().__init__(width, height, external_vcc)
def write_cmd(self, cmd):
self.temp[0] = 0x80 # Co=1, D/C#=0
self.temp[1] = cmd
self.i2c.writeto(self.addr, self.temp)
def write_framebuf(self):
# Blast out the frame buffer using a single I2C transaction to support
# hardware I2C interfaces.
self.i2c.writeto(self.addr, self.buffer)
def poweron(self):
pass
class SSD1306_SPI(SSD1306):
def __init__(self, width, height, spi, dc, res, cs, external_vcc=False):
self.rate = 10 * 1024 * 1024
dc.init(dc.OUT, value=0)
res.init(res.OUT, value=0)
cs.init(cs.OUT, value=1)
self.spi = spi
self.dc = dc
self.res = res
self.cs = cs
self.buffer = bytearray((height // 8) * width)
self.framebuf = framebuf.FrameBuffer1(self.buffer, width, height)
super().__init__(width, height, external_vcc)
def write_cmd(self, cmd):
self.spi.init(baudrate=self.rate, polarity=0, phase=0)
self.cs.high()
self.dc.low()
self.cs.low()
self.spi.write(bytearray([cmd]))
self.cs.high()
def write_framebuf(self):
self.spi.init(baudrate=self.rate, polarity=0, phase=0)
self.cs.high()
self.dc.high()
self.cs.low()
self.spi.write(self.buffer)
self.cs.high()
def poweron(self):
self.res.high()
time.sleep_ms(1)
self.res.low()
time.sleep_ms(10)
self.res.high()
I2C使用方法
查找OLEDI2C地址
在使用前，需要在putty中查找OLED的地址，并在ssd1306.py的SSD1306_I2C类中对addr进行特定的修改才能正常使用。
from pyb import I2C
i2c = I2C(2) # create on bus 2
i2c.init(I2C.MASTER, baudrate=20000)
i2c.scan()
返回的列表中的地址即为OLED的地址，将ssd1306.py的SSD1306_I2C类中对addr更改为你返回的地址即可，我这里是60。
主函数代码
from machine import I2C,Pin
from ssd1306 import SSD1306_I2C
if __name__ == "__main__":
i2c = I2C(scl = Pin("X9"),sda = Pin("X10"),freq = 10000) #软件I2C
oled = SSD1306_I2C(128, 64, i2c) #创建oled对象
oled.text("Hello World!",0,0)
oled.text("i love u!",20,40)
oled.show()
显示动态数值
from machine import I2C,Pin
from ssd1306 import SSD1306_I2C
def mainTimer_cb(cb):
'''
#函数功能：用于总体程序的逻辑定时功能
'''
global count
LED(3).toggle()
count += 1
print(count)
if __name__ == "__main__":
count = 0
mainTimer = Timer(1, freq=2, callback=mainTimer_cb) # 主程序逻辑控制定时器
i2c = I2C(scl = Pin("X9"),sda = Pin("X10"),freq = 10000) #软件I2C
oled = SSD1306_I2C(128, 64, i2c) #创建oled对象
oled.text("Hello World!",0,0)
oled.text("i love u!",20,40)
oled.show()
while True:
if (count%8) == 0: #
LED(2).toggle()
elif (count%20) == 0:
count = 0
if (count%5) == 0:
text = str(count)
oled.fill(0)
text = str(count)
oled.text(text,50,0)
oled.show()
需要注意的是： OLED的所有子函数均不能在定时器中刷新，否则会报错Memory Error！
效果展示
