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MicroPython内核开发笔记书内软件用例：I2C部分的实验

tsinghuazhuoqing 发表于 2022/07/03 00:42:13 2022/07/03

【摘要】简介：本文给出了 MicroPython内核开发笔记：书内嵌入实验任务中的 I2C 件用例部分内容。关键词： MM32F3277，MicroPython，SofiI2C，I2C ...

简介：本文给出了 MicroPython内核开发笔记：书内嵌入实验任务 中的 I2C 件用例部分内容。

关键词： MM32F3277，MicroPython，SofiI2C，I2C

本书稿内容隶属于 MicroPython内核开发笔记：书内嵌入实验任务 中的内容。

软件用例：
这部分书稿内容包括有：
1.
2.

书稿内位置：

§01 书稿内容

一、基础实验

1、SoftI2C初始化

下面代码给出了初始化一个 SoftI2C 总线接口的过程，通过 print ，dir 两个命令观察 SoftI2C 总线的属性以及提供接口函数。

from machine                import Pin,I2C,SoftI2C

scl = Pin('PA0')
sda = Pin('PA1')

i2c = SoftI2C(scl, sda, freq=100000)

print(i2c)
dir(i2c)

  
 
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上述代码运行结果为：

SoftI2C(scl=PA0, sda=PA1, freq=100000)
['readinto', 'start', 'stop', 'write', 'init', 'readfrom', 'readfrom_into', 'readfrom_mem', 'readfrom_mem_into', 'scan', 'writeto', 'writeto_mem', 'writevto']
>>> 

  
 
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一个 SoftI2C 对象提供了以下接口函数：

tart ：产生 I2C 起始状态信号；
top ：产生 I2C 停止状态信号；
can：扫错 I2C 总线上设备；
readfrom，readfrom_into，readfrom_mem, readfrom_memo_into：从外部设备读入字节；
writeto，writevto，writeto_mem：将字节写入接收设备；

2、观察SoftI2C信号

（1）扫描器件波形

下面代码利用 PC6，PC7 作为 SoftI2C 的 SCL，SDA信号。重复执行 i2c.scan() 命令。使用示波器测量 SCL，SDA 信号波形。

from machine                import Pin,I2C,SoftI2C
import time

scl = Pin('PC6')
sda = Pin('PC7')

i2c = SoftI2C(scl, sda, freq=100000)

while True:
    i2c.scan()
    time.sleep_ms(20)

  
 
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示波器抓取到的 SCL，SDA 信号波形如下。可以看到 I2C 中的 scan 函数，执行对 I2C 总线所有可能的地址进行扫描，获得有响应器件的地址。

▲ 图1.1.1 SCL,SDA信号波形

在 PLUS-F3270 实验板上包含有两个 I2C 器件，一个是MPU6050，另外一个是 K24C02。MPU6050对应的 I2C 地址为 0x68，K24C02对于的 I2C 地址为 0x50。

▲ 图1.1.2 PLUS-F3270实验板上的两个I2C器件

使用 I2C 的 scan 函数，得到的结果为： [80, 104]，分别是K24C02， MPU6050 的 I2C 地址。

3、读写 K24C02

下面代码将 0 ~ 7 八个字节写入 K24C02 前八个字节。

from machine                import Pin,SoftI2C
import time

scl = Pin('PC6')
sda = Pin('PC7')

i2c = SoftI2C(scl, sda, freq=100000)

buf = bytes((0x0,0,1,2,3,4,5,6,7))
i2c.writeto(0x50, buf)
time.sleep_ms(10)

  
 
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下面重新读取前八个字节。前两个语句实际上执行一个空写指令，是为了设置 EEPROM 当前的地址指针。然后连续读取 0x10 数字显示出来。

buf = bytes((0x0,))
i2c.writeto(0x50, buf)

buf = i2c.readfrom(0x50, 0x20)
print(buf)

  
 
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执行结果为：

1
b'\x00\x01\x02\x03\x04\x05\x06\x07\xff\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff'

  
 
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第一数字 1 是 i2c.writeto 执行后，返回实际 I2C 总线传输字节个数。后面 16 个字节数字，前八个是前面写入的数字，后面八个仍然保持为 0xff 。

二、操作I2C接口OLED

1、两线接口OLED

OLED显示屏是常用的设备输出器件，它通常具有两种接口：

七线接口：除了电源（VDD，GND）之外，还有时钟（SCK）、数据（SDA），复位（RES），功能（DC）以及片选（CS）信号；
四线接口：除了电源（VDD,GND）之外，包括I2C总结两个接口SCK， SDA。

▲ 图1.2.1 128×64 OLED液晶显示屏 左：期限接口OLED；右：四线接口OLED

四线接口，实际上就是 I2C 总线接口。下面将 I2C 总结接口的 OLED 连接到简易实验板的 PA0，PA1 两个管脚上。

▲ 图1.2.2 在面包板上将两线OLED与简易实验板连接

2、扫描OLED地址

使用 I2C 的 scan 函数测试 OLED的 I2C 地址。

from machine                import Pin,SoftI2C
import utime

print("Test I2C")

scl = Pin('PA0')
sda = Pin('PA1')

i2c = SoftI2C(scl, sda, freq=100000)

ret = i2c.scan()
print(ret)

  
 
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程序运行结果为：

Test I2C
[60]

  
 
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3、液晶初始化

下面给出了对于 OLED 进行初始化的代码，这个代码将 OLED平面显示为白色。

from machine                import Pin,SoftI2C
import utime
from micropython import const
#------------------------------------------------------------
scl = Pin('PA0')
sda = Pin('PA1')
i2c = SoftI2C(scl, sda, freq=100000)
#------------------------------------------------------------
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
        self.buffer = bytearray(self.pages * self.width)
        self.init_display()
    def init_display(self):
        for cmd in (
            SET_DISP | 0x00,            # off
            SET_MEM_ADDR, 0x00,         # horizontal
            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,
            SET_DISP_CLK_DIV, 0x80,
            SET_PRECHARGE, 0x22 if self.external_vcc else 0xf1,
            SET_VCOM_DESEL, 0x30,       # 0.83*Vcc
            SET_CONTRAST, 0xff,         # maximum
            SET_ENTIRE_ON,              # output follows RAM contents
            SET_NORM_INV,               # not inverted
            SET_CHARGE_PUMP, 0x10 if self.external_vcc else 0x14,
            SET_DISP | 0x01):           # on
            self.write_cmd(cmd)
        self.fill(0xff)
        self.show()
    def fill(self, c):
        for i in range(len(self.buffer)):
            self.buffer[i] = c
    def poweroff(self):
        self.write_cmd(SET_DISP | 0x00)
    def poweron(self):
        self.write_cmd(SET_DISP | 0x01)
    def contrast(self, contrast):
        self.write_cmd(SET_CONTRAST)
        self.write_cmd(contrast)
    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:
            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_data(self.buffer)
class SSD1306_I2C(SSD1306):
    def __init__(self, width, height, i2c, addr=0x3c, external_vcc=False):
        self.i2c = i2c
        self.addr = addr
        self.temp = bytearray(2)
        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_data(self, buf):
        self.temp[0] = self.addr << 1
        self.temp[1] = 0x40         # Co=0, D/C#=1
        self.i2c.start()
        self.i2c.write(self.temp)
        self.i2c.write(buf)
        self.i2c.stop()
#------------------------------------------------------------
oled = SSD1306_I2C(128, 64, i2c, addr=0x3c)


  
 
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下面动图显示了 OLED 被初始化的放慢的过程。

▲ 图1.2.3 SoftI2C初始化OLED

4、显示字符信息

下面代码给出了在 OLED上显示字符的示例程序。

from machine                import Pin,SoftI2C
import utime
from micropython import const

scl = Pin('PA0')
sda = Pin('PA1')

i2c = SoftI2C(scl, sda, freq=400000)

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)

font8x16 = bytes((0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0xF8,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x33,0x30,0x00,0x00,0x00,
  0x00,0x10,0x0C,0x06,0x10,0x0C,0x06,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
  0x40,0xC0,0x78,0x40,0xC0,0x78,0x40,0x00,0x04,0x3F,0x04,0x04,0x3F,0x04,0x04,0x00,
  0x00,0x70,0x88,0xFC,0x08,0x30,0x00,0x00,0x00,0x18,0x20,0xFF,0x21,0x1E,0x00,0x00,
  0xF0,0x08,0xF0,0x00,0xE0,0x18,0x00,0x00,0x00,0x21,0x1C,0x03,0x1E,0x21,0x1E,0x00,
  0x00,0xF0,0x08,0x88,0x70,0x00,0x00,0x00,0x1E,0x21,0x23,0x24,0x19,0x27,0x21,0x10,
  0x10,0x16,0x0E,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0xE0,0x18,0x04,0x02,0x00,0x00,0x00,0x00,0x07,0x18,0x20,0x40,0x00,
  0x00,0x02,0x04,0x18,0xE0,0x00,0x00,0x00,0x00,0x40,0x20,0x18,0x07,0x00,0x00,0x00,
  0x40,0x40,0x80,0xF0,0x80,0x40,0x40,0x00,0x02,0x02,0x01,0x0F,0x01,0x02,0x02,0x00,
  0x00,0x00,0x00,0xF0,0x00,0x00,0x00,0x00,0x01,0x01,0x01,0x1F,0x01,0x01,0x01,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x80,0xB0,0x70,0x00,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x01,0x01,0x01,0x01,0x01,0x01,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x30,0x30,0x00,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0x80,0x60,0x18,0x04,0x00,0x60,0x18,0x06,0x01,0x00,0x00,0x00,
  0x00,0xE0,0x10,0x08,0x08,0x10,0xE0,0x00,0x00,0x0F,0x10,0x20,0x20,0x10,0x0F,0x00,
  0x00,0x10,0x10,0xF8,0x00,0x00,0x00,0x00,0x00,0x20,0x20,0x3F,0x20,0x20,0x00,0x00,
  0x00,0x70,0x08,0x08,0x08,0x88,0x70,0x00,0x00,0x30,0x28,0x24,0x22,0x21,0x30,0x00,
  0x00,0x30,0x08,0x88,0x88,0x48,0x30,0x00,0x00,0x18,0x20,0x20,0x20,0x11,0x0E,0x00,
  0x00,0x00,0xC0,0x20,0x10,0xF8,0x00,0x00,0x00,0x07,0x04,0x24,0x24,0x3F,0x24,0x00,
  0x00,0xF8,0x08,0x88,0x88,0x08,0x08,0x00,0x00,0x19,0x21,0x20,0x20,0x11,0x0E,0x00,
  0x00,0xE0,0x10,0x88,0x88,0x18,0x00,0x00,0x00,0x0F,0x11,0x20,0x20,0x11,0x0E,0x00,
  0x00,0x38,0x08,0x08,0xC8,0x38,0x08,0x00,0x00,0x00,0x00,0x3F,0x00,0x00,0x00,0x00,
  0x00,0x70,0x88,0x08,0x08,0x88,0x70,0x00,0x00,0x1C,0x22,0x21,0x21,0x22,0x1C,0x00,
  0x00,0xE0,0x10,0x08,0x08,0x10,0xE0,0x00,0x00,0x00,0x31,0x22,0x22,0x11,0x0F,0x00,
  0x00,0x00,0x00,0xC0,0xC0,0x00,0x00,0x00,0x00,0x00,0x00,0x30,0x30,0x00,0x00,0x00,
  0x00,0x00,0x00,0x80,0x00,0x00,0x00,0x00,0x00,0x00,0x80,0x60,0x00,0x00,0x00,0x00,
  0x00,0x00,0x80,0x40,0x20,0x10,0x08,0x00,0x00,0x01,0x02,0x04,0x08,0x10,0x20,0x00,
  0x40,0x40,0x40,0x40,0x40,0x40,0x40,0x00,0x04,0x04,0x04,0x04,0x04,0x04,0x04,0x00,
  0x00,0x08,0x10,0x20,0x40,0x80,0x00,0x00,0x00,0x20,0x10,0x08,0x04,0x02,0x01,0x00,
  0x00,0x70,0x48,0x08,0x08,0x08,0xF0,0x00,0x00,0x00,0x00,0x30,0x36,0x01,0x00,0x00,
  0xC0,0x30,0xC8,0x28,0xE8,0x10,0xE0,0x00,0x07,0x18,0x27,0x24,0x23,0x14,0x0B,0x00,
  0x00,0x00,0xC0,0x38,0xE0,0x00,0x00,0x00,0x20,0x3C,0x23,0x02,0x02,0x27,0x38,0x20,
  0x08,0xF8,0x88,0x88,0x88,0x70,0x00,0x00,0x20,0x3F,0x20,0x20,0x20,0x11,0x0E,0x00,
  0xC0,0x30,0x08,0x08,0x08,0x08,0x38,0x00,0x07,0x18,0x20,0x20,0x20,0x10,0x08,0x00,
  0x08,0xF8,0x08,0x08,0x08,0x10,0xE0,0x00,0x20,0x3F,0x20,0x20,0x20,0x10,0x0F,0x00,
  0x08,0xF8,0x88,0x88,0xE8,0x08,0x10,0x00,0x20,0x3F,0x20,0x20,0x23,0x20,0x18,0x00,
  0x08,0xF8,0x88,0x88,0xE8,0x08,0x10,0x00,0x20,0x3F,0x20,0x00,0x03,0x00,0x00,0x00,
  0xC0,0x30,0x08,0x08,0x08,0x38,0x00,0x00,0x07,0x18,0x20,0x20,0x22,0x1E,0x02,0x00,
  0x08,0xF8,0x08,0x00,0x00,0x08,0xF8,0x08,0x20,0x3F,0x21,0x01,0x01,0x21,0x3F,0x20,
  0x00,0x08,0x08,0xF8,0x08,0x08,0x00,0x00,0x00,0x20,0x20,0x3F,0x20,0x20,0x00,0x00,
  0x00,0x00,0x08,0x08,0xF8,0x08,0x08,0x00,0xC0,0x80,0x80,0x80,0x7F,0x00,0x00,0x00,
  0x08,0xF8,0x88,0xC0,0x28,0x18,0x08,0x00,0x20,0x3F,0x20,0x01,0x26,0x38,0x20,0x00,
  0x08,0xF8,0x08,0x00,0x00,0x00,0x00,0x00,0x20,0x3F,0x20,0x20,0x20,0x20,0x30,0x00,
  0x08,0xF8,0xF8,0x00,0xF8,0xF8,0x08,0x00,0x20,0x3F,0x00,0x3F,0x00,0x3F,0x20,0x00,
  0x08,0xF8,0x30,0xC0,0x00,0x08,0xF8,0x08,0x20,0x3F,0x20,0x00,0x07,0x18,0x3F,0x00,
  0xE0,0x10,0x08,0x08,0x08,0x10,0xE0,0x00,0x0F,0x10,0x20,0x20,0x20,0x10,0x0F,0x00,
  0x08,0xF8,0x08,0x08,0x08,0x08,0xF0,0x00,0x20,0x3F,0x21,0x01,0x01,0x01,0x00,0x00,
  0xE0,0x10,0x08,0x08,0x08,0x10,0xE0,0x00,0x0F,0x18,0x24,0x24,0x38,0x50,0x4F,0x00,
  0x08,0xF8,0x88,0x88,0x88,0x88,0x70,0x00,0x20,0x3F,0x20,0x00,0x03,0x0C,0x30,0x20,
  0x00,0x70,0x88,0x08,0x08,0x08,0x38,0x00,0x00,0x38,0x20,0x21,0x21,0x22,0x1C,0x00,
  0x18,0x08,0x08,0xF8,0x08,0x08,0x18,0x00,0x00,0x00,0x20,0x3F,0x20,0x00,0x00,0x00,
  0x08,0xF8,0x08,0x00,0x00,0x08,0xF8,0x08,0x00,0x1F,0x20,0x20,0x20,0x20,0x1F,0x00,
  0x08,0x78,0x88,0x00,0x00,0xC8,0x38,0x08,0x00,0x00,0x07,0x38,0x0E,0x01,0x00,0x00,
  0xF8,0x08,0x00,0xF8,0x00,0x08,0xF8,0x00,0x03,0x3C,0x07,0x00,0x07,0x3C,0x03,0x00,
  0x08,0x18,0x68,0x80,0x80,0x68,0x18,0x08,0x20,0x30,0x2C,0x03,0x03,0x2C,0x30,0x20,
  0x08,0x38,0xC8,0x00,0xC8,0x38,0x08,0x00,0x00,0x00,0x20,0x3F,0x20,0x00,0x00,0x00,
  0x10,0x08,0x08,0x08,0xC8,0x38,0x08,0x00,0x20,0x38,0x26,0x21,0x20,0x20,0x18,0x00,
  0x00,0x00,0x00,0xFE,0x02,0x02,0x02,0x00,0x00,0x00,0x00,0x7F,0x40,0x40,0x40,0x00,
  0x00,0x0C,0x30,0xC0,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x06,0x38,0xC0,0x00,
  0x00,0x02,0x02,0x02,0xFE,0x00,0x00,0x00,0x00,0x40,0x40,0x40,0x7F,0x00,0x00,0x00,
  0x00,0x00,0x04,0x02,0x02,0x02,0x04,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,
  0x00,0x02,0x02,0x04,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
  0x00,0x00,0x80,0x80,0x80,0x80,0x00,0x00,0x00,0x19,0x24,0x22,0x22,0x22,0x3F,0x20,
  0x08,0xF8,0x00,0x80,0x80,0x00,0x00,0x00,0x00,0x3F,0x11,0x20,0x20,0x11,0x0E,0x00,
  0x00,0x00,0x00,0x80,0x80,0x80,0x00,0x00,0x00,0x0E,0x11,0x20,0x20,0x20,0x11,0x00,
  0x00,0x00,0x00,0x80,0x80,0x88,0xF8,0x00,0x00,0x0E,0x11,0x20,0x20,0x10,0x3F,0x20,
  0x00,0x00,0x80,0x80,0x80,0x80,0x00,0x00,0x00,0x1F,0x22,0x22,0x22,0x22,0x13,0x00,
  0x00,0x80,0x80,0xF0,0x88,0x88,0x88,0x18,0x00,0x20,0x20,0x3F,0x20,0x20,0x00,0x00,
  0x00,0x00,0x80,0x80,0x80,0x80,0x80,0x00,0x00,0x6B,0x94,0x94,0x94,0x93,0x60,0x00,
  0x08,0xF8,0x00,0x80,0x80,0x80,0x00,0x00,0x20,0x3F,0x21,0x00,0x00,0x20,0x3F,0x20,
  0x00,0x80,0x98,0x98,0x00,0x00,0x00,0x00,0x00,0x20,0x20,0x3F,0x20,0x20,0x00,0x00,
  0x00,0x00,0x00,0x80,0x98,0x98,0x00,0x00,0x00,0xC0,0x80,0x80,0x80,0x7F,0x00,0x00,
  0x08,0xF8,0x00,0x00,0x80,0x80,0x80,0x00,0x20,0x3F,0x24,0x02,0x2D,0x30,0x20,0x00,
  0x00,0x08,0x08,0xF8,0x00,0x00,0x00,0x00,0x00,0x20,0x20,0x3F,0x20,0x20,0x00,0x00,
  0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x00,0x20,0x3F,0x20,0x00,0x3F,0x20,0x00,0x3F,
  0x80,0x80,0x00,0x80,0x80,0x80,0x00,0x00,0x20,0x3F,0x21,0x00,0x00,0x20,0x3F,0x20,
  0x00,0x00,0x80,0x80,0x80,0x80,0x00,0x00,0x00,0x1F,0x20,0x20,0x20,0x20,0x1F,0x00,
  0x80,0x80,0x00,0x80,0x80,0x00,0x00,0x00,0x80,0xFF,0xA1,0x20,0x20,0x11,0x0E,0x00,
  0x00,0x00,0x00,0x80,0x80,0x80,0x80,0x00,0x00,0x0E,0x11,0x20,0x20,0xA0,0xFF,0x80,
  0x80,0x80,0x80,0x00,0x80,0x80,0x80,0x00,0x20,0x20,0x3F,0x21,0x20,0x00,0x01,0x00,
  0x00,0x00,0x80,0x80,0x80,0x80,0x80,0x00,0x00,0x33,0x24,0x24,0x24,0x24,0x19,0x00,
  0x00,0x80,0x80,0xE0,0x80,0x80,0x00,0x00,0x00,0x00,0x00,0x1F,0x20,0x20,0x00,0x00,
  0x80,0x80,0x00,0x00,0x00,0x80,0x80,0x00,0x00,0x1F,0x20,0x20,0x20,0x10,0x3F,0x20,
  0x80,0x80,0x80,0x00,0x00,0x80,0x80,0x80,0x00,0x01,0x0E,0x30,0x08,0x06,0x01,0x00,
  0x80,0x80,0x00,0x80,0x00,0x80,0x80,0x80,0x0F,0x30,0x0C,0x03,0x0C,0x30,0x0F,0x00,
  0x00,0x80,0x80,0x00,0x80,0x80,0x80,0x00,0x00,0x20,0x31,0x2E,0x0E,0x31,0x20,0x00,
  0x80,0x80,0x80,0x00,0x00,0x80,0x80,0x80,0x80,0x81,0x8E,0x70,0x18,0x06,0x01,0x00,
  0x00,0x80,0x80,0x80,0x80,0x80,0x80,0x00,0x00,0x21,0x30,0x2C,0x22,0x21,0x30,0x00,
  0x00,0x00,0x00,0x00,0x80,0x7C,0x02,0x02,0x00,0x00,0x00,0x00,0x00,0x3F,0x40,0x40,
  0x00,0x00,0x00,0x00,0xFF,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xFF,0x00,0x00,0x00,
  0x00,0x02,0x02,0x7C,0x80,0x00,0x00,0x00,0x00,0x40,0x40,0x3F,0x00,0x00,0x00,0x00,
  0x00,0x06,0x01,0x01,0x02,0x02,0x04,0x04,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00))

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
        self.buffer = bytearray(self.pages * self.width)
        self.init_display()

    def init_display(self):
        for cmd in (
            SET_DISP | 0x00,            # off
            SET_MEM_ADDR, 0x00,         # horizontal
            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,
            SET_DISP_CLK_DIV, 0x80,
            SET_PRECHARGE, 0x22 if self.external_vcc else 0xf1,
            SET_VCOM_DESEL, 0x30,       # 0.83*Vcc
            SET_CONTRAST, 0xff,         # maximum
            SET_ENTIRE_ON,              # output follows RAM contents
            SET_NORM_INV,               # not inverted
            SET_CHARGE_PUMP, 0x10 if self.external_vcc else 0x14,
            SET_DISP | 0x01):           # on
            self.write_cmd(cmd)
        self.fill(0x0)
        self.show()

    def fill(self, c):
        for i in range(len(self.buffer)):
            self.buffer[i] = c

    def poweroff(self):
        self.write_cmd(SET_DISP | 0x00)

    def poweron(self):
        self.write_cmd(SET_DISP | 0x01)

    def contrast(self, contrast):
        self.write_cmd(SET_CONTRAST)
        self.write_cmd(contrast)

    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:
            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_data(self.buffer)

    def setpoint(self, x,y):
        liney = y//8
        yy = 1<<(y%8)
        self.buffer[liney*self.width+x] |= yy

    def setstring(self, x,y,str):
        for c in str:
            cid = ord(c) - 0x20
            cid *= 16
            for i in range(8):
                ii = y*self.width+x*8+i
                self.buffer[ii] = font8x16[cid+i]
                self.buffer[ii+self.width] = font8x16[cid+i+8]

            x += 1
            if x >= self.width//8:
                x = 0
                y += 1

class SSD1306_I2C(SSD1306):
    def __init__(self, width, height, i2c, addr=0x3c, external_vcc=False):
        self.i2c = i2c
        self.addr = addr
        self.temp = bytearray(2)
        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_data(self, buf):
        self.temp[0] = self.addr << 1
        self.temp[1] = 0x40         # Co=0, D/C#=1
        self.i2c.start()
        self.i2c.write(self.temp)
        self.i2c.write(buf)
        self.i2c.stop()

oled = SSD1306_I2C(128, 64, i2c, addr=0x3c)

oled.setstring(0, 0, '  MM32F3277')
oled.setstring(0, 2, 'MicroPython:V2')
oled.show()

count = 0
while True:
    oled.setstring(3, 6, 'Count:%04d'%count)
    count += 1
    oled.show()

    utime.sleep_ms(100)

  
 
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▲ 图1 利用 SoftI2C 控制OLED显示字符信息

※ 总结 ※

本文给出了 MicroPython内核开发笔记：书内嵌入实验任务 中的 I2C 件用例部分内容。

■ 相关文献链接:

MicroPython内核开发笔记：书内嵌入实验任务

● 相关图表链接:

图1.1.1 SCL,SDA信号波形
图1.1.2 PLUS-F3270实验板上的两个I2C器件
图1.2.2 在面包板上将两线OLED与简易实验板连接
图1.2.3 SoftI2C初始化OLED
图1 利用 SoftI2C 控制OLED显示字符信息

文章来源: zhuoqing.blog.csdn.net，作者：卓晴，版权归原作者所有，如需转载，请联系作者。

原文链接：zhuoqing.blog.csdn.net/article/details/125564410

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MicroPython内核开发笔记书内软件用例：I2C部分的实验

§01 书稿内容

一、基础实验

1、SoftI2C初始化

2、观察SoftI2C信号

（1）扫描器件波形

3、读写 K24C02

二、操作I2C接口OLED

1、两线接口OLED

2、扫描OLED地址

3、液晶初始化

4、显示字符信息

※ 总结 ※

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MicroPython内核开发笔记书内软件用例 ：I2C部分的实验

§01 书稿内容

一、基础实验

1、SoftI2C初始化

2、观察SoftI2C信号

（1）扫描器件波形

3、读写 K24C02

二、操作I2C接口OLED

1、两线接口OLED

2、扫描OLED地址

3、液晶初始化

4、显示字符信息

※ 总 结 ※

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MicroPython内核开发笔记书内软件用例：I2C部分的实验

※ 总结 ※