一、概述

    前面介绍了在MicroPython环境下，采用Thonny工具，对板上的LED灯与PWM接口进行简单的应用编程。根据实验测试结果，程序基本上与RP2040共用。接下来使用IIC接口驱动SSD1315，SPI接口驱动MAX7219点阵屏，验证其与RP2040兼容性。

二、管脚连接关系

    实物硬件连线详情如下：

    根据官方给出的pin脚定义图，可合理定义输出控制脚。

      应用到管脚对应关系如下：

        实物连线示意图如下：

三、驱动代码

            由于ssd1306与ssd1315的驱动兼容，因此这里笔者采用驱动ssd1306 0.96寸屏的代码。

# MicroPython SSD1306 OLED driver, I2C and SPI interfaces

from micropython import const
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)

# Subclassing FrameBuffer provides support for graphics primitives
# http://docs.micropython.org/en/latest/pyboard/library/framebuf.html
class SSD1306(framebuf.FrameBuffer):
    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)
        super().__init__(self.buffer, self.width, self.height, framebuf.MONO_VLSB)
        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.width > 2 * self.height 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 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:
            # 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_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)
        self.write_list = [b"\x40", None]  # Co=0, D/C#=1
        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.write_list[1] = buf
        self.i2c.writevto(self.addr, self.write_list)

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
        import time

        self.res(1)
        time.sleep_ms(1)
        self.res(0)
        time.sleep_ms(10)
        self.res(1)
        super().__init__(width, height, external_vcc)

    def write_cmd(self, cmd):
        self.spi.init(baudrate=self.rate, polarity=0, phase=0)
        self.cs(1)
        self.dc(0)
        self.cs(0)
        self.spi.write(bytearray([cmd]))
        self.cs(1)

    def write_data(self, buf):
        self.spi.init(baudrate=self.rate, polarity=0, phase=0)
        self.cs(1)
        self.dc(1)
        self.cs(0)
        self.spi.write(buf)
        self.cs(1)

        基于MAX7219的8x8点阵屏的驱动源码如下：

from micropython import const
import framebuf

_NOOP = const(0)
_DIGIT0 = const(1)
_DECODEMODE = const(9)
_INTENSITY = const(10)
_SCANLIMIT = const(11)
_SHUTDOWN = const(12)
_DISPLAYTEST = const(15)

class Matrix8x8:
    def __init__(self, spi, cs, num):
        """
        Driver for cascading MAX7219 8x8 LED matrices.

        >>> import max7219
        >>> from machine import Pin, SPI
        >>> spi = SPI(1)
        >>> display = max7219.Matrix8x8(spi, Pin('X5'), 4)
        >>> display.text('1234',0,0,1)
        >>> display.show()

        """
        self.spi = spi
        self.cs = cs
        self.cs.init(cs.OUT, True)
        self.buffer = bytearray(8 * num)
        self.num = num
        fb = framebuf.FrameBuffer(self.buffer, 8 * num, 8, framebuf.MONO_HLSB)
        self.framebuf = fb
        # Provide methods for accessing FrameBuffer graphics primitives. This is a workround
        # because inheritance from a native class is currently unsupported.
        # http://docs.micropython.org/en/latest/pyboard/library/framebuf.html
        self.fill = fb.fill  # (col)
        self.pixel = fb.pixel # (x, y[, c])
        self.hline = fb.hline  # (x, y, w, col)
        self.vline = fb.vline  # (x, y, h, col)
        self.line = fb.line  # (x1, y1, x2, y2, col)
        self.rect = fb.rect  # (x, y, w, h, col)
        self.fill_rect = fb.fill_rect  # (x, y, w, h, col)
        self.text = fb.text  # (string, x, y, col=1)
        self.scroll = fb.scroll  # (dx, dy)
        self.blit = fb.blit  # (fbuf, x, y[, key])
        self.init()

    def _write(self, command, data):
        self.cs(0)
        for m in range(self.num):
            self.spi.write(bytearray([command, data]))
        self.cs(1)

    def init(self):
        for command, data in (
            (_SHUTDOWN, 0),
            (_DISPLAYTEST, 0),
            (_SCANLIMIT, 7),
            (_DECODEMODE, 0),
            (_SHUTDOWN, 1),
        ):
            self._write(command, data)

    def brightness(self, value):
        if not 0 <= value <= 15:
            raise ValueError("Brightness out of range")
        self._write(_INTENSITY, value)

    def show(self):
        for y in range(8):
            self.cs(0)
            for m in range(self.num):
                self.spi.write(bytearray([_DIGIT0 + y, self.buffer[(y * self.num) + m]]))
            self.cs(1)

四、应用代码编写

            上述关于ssd1306、max7219的驱动代码都已开源，均可在github上获取。将上述展示的两个py驱动文件保存到“Raspberry Pi Pico”设备中，这是必须的，否则后面的应用源码去调用“ssd1306”、“max7219”模块后报错。接下来编写main.py，如果用户需要开机立马运行编写的应用代码，则需要将main.py保存到“Raspberry Pi Pico”设备中；如果只需要在线调试，借助Thonny中的运行图标进行测试，则可将main.py保存到“此电脑”。

       main.py代码如下：

from machine import SoftI2C, Pin
# 导入SSD1306驱动模块
from ssd1306 import SSD1306_I2C

import max7219
from machine import Pin, SPI
from time import sleep
spi = SPI(0, baudrate=10000000, polarity=1, phase=0, sck=Pin(2), mosi=Pin(3))
ss = Pin(5, Pin.OUT)

CH_16 = {
    "欢": [
        0x00,0x80,0x00,0x80,0xFC,0x80,0x04,0xFC,0x05,0x04,0x49,0x08,0x2A,0x40,0x14,0x40,
        0x10,0x40,0x28,0xA0,0x24,0xA0,0x45,0x10,0x81,0x10,0x02,0x08,0x04,0x04,0x08,0x02,
    ],
    "迎": [
        0x00,0x00,0x20,0x80,0x13,0x3C,0x12,0x24,0x02,0x24,0x02,0x24,0xF2,0x24,0x12,0x24,
        0x12,0x24,0x12,0xB4,0x13,0x28,0x12,0x20,0x10,0x20,0x28,0x20,0x47,0xFE,0x00,0x00,
    ],
    "使": [
        0x10,0x40,0x10,0x40,0x1F,0xFE,0x20,0x40,0x20,0x40,0x67,0xFC,0x64,0x44,0xA4,0x44,
        0x27,0xFC,0x20,0x40,0x22,0x40,0x21,0x40,0x20,0x80,0x21,0x40,0x22,0x30,0x2C,0x0E,
    ],
    "用": [
        0x00,0x00,0x3F,0xF8,0x21,0x08,0x21,0x08,0x21,0x08,0x3F,0xF8,0x21,0x08,0x21,0x08,
        0x21,0x08,0x3F,0xF8,0x21,0x08,0x21,0x08,0x21,0x08,0x41,0x08,0x41,0x28,0x80,0x10,
    ],
    "树": [
        0x20,0x04,0x20,0x04,0x27,0x84,0x20,0x84,0xF8,0xBE,0x24,0x84,0x22,0x84,0x72,0xA4,
        0x69,0x14,0xA1,0x14,0xA2,0x84,0x22,0x84,0x24,0x84,0x28,0x04,0x20,0x14,0x20,0x08,
    ],
    "莓": [
        0x04,0x40,0x04,0x40,0xFF,0xFE,0x14,0x40,0x10,0x00,0x3F,0xFC,0x40,0x00,0x9F,0xF0,
        0x12,0x10,0x11,0x10,0xFF,0xFE,0x22,0x10,0x21,0x10,0x3F,0xFC,0x00,0x10,0x00,0x60,
    ],
    "派": [
        0x00,0x08,0x20,0x3C,0x17,0xC0,0x14,0x00,0x84,0x1C,0x45,0xE0,0x45,0x20,0x15,0x22,
        0x15,0x24,0x25,0x28,0xE5,0x10,0x25,0x10,0x25,0x08,0x29,0x44,0x29,0x82,0x11,0x00,
    ],
}

# 绘制单个 16x16 汉字
def draw_ch16_char(oled, char, x, y):
    if char in CH_16:
        data = CH_16[char]
        for row in range(16):  # 遍历 16 行
            byte_high = data[row * 2]     # 高字节
            byte_low = data[row * 2 + 1]  # 低字节
            for col in range(16):         # 遍历 16 列
                if col < 8:
                    pixel = byte_high & (0x80 >> col)  # 解析高字节
                else:
                    pixel = byte_low & (0x80 >> (col - 8))  # 解析低字节
                if pixel:
                    oled.pixel(x + col, y + row, 1)  # 绘制像素
    else:
        print(f"字符 {char} 不在字库中")

if __name__ == '__main__':
    # 初始化SoftI2C
    # OLED屏幕的scl连接到树莓派PICO的GPIO1, sda连接到GPIO0
    i2c = SoftI2C(scl=Pin(1), sda=Pin(0))
    # oled = SSD1306_I2C(width, height, i2c, addr)
    # width:屏幕宽
    # height: 屏幕高
    # i2c:已定义的I2C对象
    oled = SSD1306_I2C(128, 64, i2c) #OLED显示屏初始化：128*64分辨率,OLED的I2C地址是0x3c
    # OLED显示的字符串，横坐标和纵坐标
    oled.text("Welcome To XCC!", 0, 0)
    draw_ch16_char(oled, "欢", 0,  24)
    draw_ch16_char(oled, "迎", 16, 24)
    draw_ch16_char(oled, "使", 32, 24)
    draw_ch16_char(oled, "用", 48, 24)
    draw_ch16_char(oled, "树", 64, 24)
    draw_ch16_char(oled, "莓", 80, 24)
    draw_ch16_char(oled, "派", 96, 24)
    oled.text("Pico2", 0, 56)
    oled.text("2025/04/24", 48, 56)
    # OLED显示
    oled.show()
    
    msg = 'Welcome To XCC! 2025-04-24'
    length = len(msg)
    length = (length*7+4)
    display = max7219.Matrix8x8(spi, ss, 4)
    display.brightness(5)   # adjust brightness 1 to 15
    display.fill(0)
    display.show()
    sleep(0.2)
    
while True: 
    for x in range(32, -length, -1):
        display.text(msg ,x,0,1)
        display.show()
        sleep(0.05)
        display.fill(0)

       应用代码中，关于OLED屏显示中文字符部分，需要借助“PCtoLCD2002”取字模工具，并选项设置如下：

五、运行效果

        工程源码见附件，附件解压后，将源码保存到“Raspberry Pi Pico”设备中，重启上电即可见如下现象。