物联网开发笔记（48）- 使用Micropython开发ESP32开发板之控制OLED ssd1306屏幕

一、目的

这一节我们学习如何使用我们的ESP32开发板来控制OLED ssd1306屏幕，此处使用的是I2C协议，大家可自行百度学习一下I2C。

二、环境

ESP32 + OLED ssd1306屏幕 + Thonny IDE（或者WOKWI在线仿真） + 几根杜邦线

本次使用在线仿真，笔者太穷了，写了那么多，也没人打赏，买不起设备了！！！

接线方法：

WOKWI在线仿真地址，国外网站，速度较慢：

Wokwi - Online Arduino and ESP32 Simulator

关于这个屏幕的具体介绍参考如下地址：

board-ssd1306 Reference | Wokwi Docs

三、代码

屏幕驱动芯片：

#MicroPython SSD1306 OLED driver, I2C and SPI interfaces created by Adafruit

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)

    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()

    def fill(self, col):
        self.framebuf.fill(col)

    def pixel(self, x, y, col):
        self.framebuf.pixel(x, y, col)

    def scroll(self, dx, dy):
        self.framebuf.scroll(dx, dy)

    def text(self, string, x, y, col=1):
        self.framebuf.text(string, x, y, col)


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)
        # 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()

示例代码1

from machine import Pin, SoftI2C  # 导入Pin和软I2C模块
from time import sleep  # 导入时间模块
import ssd1306  # 导入屏幕驱动模块


# 创建i2c对象
i2c = SoftI2C(scl=Pin(22), sda=Pin(21))  # 时钟接Pin22，数据接Pin21

# 宽度高度，屏幕宽高为128*64 像素
oled_width = 128  
oled_height = 64

# 创建oled屏幕对象
oled = ssd1306.SSD1306_I2C(oled_width, oled_height, i2c)  # 设置宽度，高度和I2C通信

# 在指定位置处显示文字
oled.text('Shanghai!', 0, 0)  # 在屏幕的左上角开始显示
oled.text('Beijing welcome!', 0, 15) 
oled.text('Guangzhou beautiful!', 0, 25)
        
oled.show()  # 显示文字

示例代码2

from machine import Pin, I2C  # 导入PIN和I2C
from ssd1306 import SSD1306_I2C  # 导入屏幕驱动

#OLED=....
i2c = I2C(scl=Pin(22), sda=Pin(21))  # 创建I2C对象
OLED= SSD1306_I2C(128, 64, i2c)  # 创建OLED对象

#fonts=....字使用字典，字典的key来放字的编码的十六进制，键来放字模
fonts= {
    0xE5A5BD:
    [0x00,0x04,0x08,0x10,0x20,0xFF,0x11,0x12,0x14,0x18,0x24,0x42,0x00,0x00,0x00,0x00,
    0x00,0x00,0xF8,0x10,0x20,0xF8,0x40,0x20,0x10,0x08,0x28,0x10,0x00,0x00,0x00,0x00],  # 好
    
    0xE4BABA:
    [0x00,0x01,0x01,0x01,0x01,0x02,0x04,0x08,0x10,0x20,0x00,0x00,0x00,0x00,0x00,0x00,
    0x00,0x00,0x00,0x00,0x00,0x80,0x40,0x20,0x10,0x08,0x00,0x00,0x00,0x00,0x00,0x00],  # 人
    
    0xE5A49A:
    [0x00,0x02,0x04,0x0F,0x18,0x25,0x02,0x0D,0x12,0x04,0x00,0x01,0x00,0x00,0x00,0x00,
    0x00,0x00,0x00,0x80,0xA0,0x40,0xF8,0x08,0xD0,0x20,0x40,0x80,0x00,0x00,0x00,0x00],  # 多
}


# 顶替中文函数部分
def chinese(ch_str, x_axis, y_axis):  # 需要显示的中文，x轴的开始位置，y轴的开始位置
   offset_ = 0  # 偏移量设为0，也可以设为其他值，俺需要修正
   for k in ch_str:   # for循环去除每个字
       code = 0x00  # 将中文转成16进制编码 
       data_code = k.encode("utf-8")  # 编码为utf-8格式
       code |= data_code[0] << 16
       code |= data_code[1] << 8
       code |= data_code[2]
       byte_data = fonts[code]
       for y in range(0, 16):
           a_ = bin(byte_data[y]).replace('0b', '')
           while len(a_) < 8:
               a_ = '0'+ a_
           b_ = bin(byte_data[y+16]).replace('0b', '')
           while len(b_) < 8:
               b_ = '0'+ b_
           for x in range(0, 8):
               OLED.pixel(x_axis + offset_ + x,     y+y_axis, int(a_[x]))   
               OLED.pixel(x_axis + offset_ + x + 8, y+y_axis, int(b_[x]))   
       offset_ += 16

chinese('好人多', 35, 4)  # 需要显示的中文
OLED.show()  # 显示
OLED.text('welcome to china', 0, 32)  # 需要显示的英文
OLED.show()  # 显示

四、演示效果

示例代码1的效果：