一般板子容量有限，8M都算很大了，如果想擴容咋辦，那就自己加sd卡，其實micropython固件自帶了machine.SDCard，但是我沒測出來，于是直接在GAY站上搜了一個，測試成功，一個sd卡擴展模塊才1.6元，問題在于一般其實沒有那么大的內存需求，加了擴展模塊需要占用一個spi口，外加CS，一共用掉4個pin
sd.py

""" MicroPython driver for SD cards using SPI bus. Requires an SPI bus and a CS pin. Provides readblocks and writeblocks methods so the device can be mounted as a filesystem. Example usage on pyboard:import pyb, sdcard, ossd = sdcard.SDCard(pyb.SPI(1), pyb.Pin.board.X5)pyb.mount(sd, '/sd2')os.listdir('/') Example usage on ESP8266:import machine, sdcard, ossd = sdcard.SDCard(machine.SPI(1), machine.Pin(15))os.mount(sd, '/sd')os.listdir('/') """from micropython import const import time_CMD_TIMEOUT = const(100)_R1_IDLE_STATE = const(1 << 0) # R1_ERASE_RESET = const(1 << 1) _R1_ILLEGAL_COMMAND = const(1 << 2) # R1_COM_CRC_ERROR = const(1 << 3) # R1_ERASE_SEQUENCE_ERROR = const(1 << 4) # R1_ADDRESS_ERROR = const(1 << 5) # R1_PARAMETER_ERROR = const(1 << 6) _TOKEN_CMD25 = const(0xFC) _TOKEN_STOP_TRAN = const(0xFD) _TOKEN_DATA = const(0xFE)class SDCard:def __init__(self, spi, cs, baudrate=1320000):self.spi = spiself.cs = csself.cmdbuf = bytearray(6)self.dummybuf = bytearray(512)self.tokenbuf = bytearray(1)for i in range(512):self.dummybuf[i] = 0xFFself.dummybuf_memoryview = memoryview(self.dummybuf)# initialise the cardself.init_card(baudrate)def init_spi(self, baudrate):try:master = self.spi.MASTERexcept AttributeError:# on ESP8266self.spi.init(baudrate=baudrate, phase=0, polarity=0)else:# on pyboardself.spi.init(master, baudrate=baudrate, phase=0, polarity=0)def init_card(self, baudrate):# init CS pinself.cs.init(self.cs.OUT, value=1)# init SPI bus; use low data rate for initialisationself.init_spi(100000)# clock card at least 100 cycles with cs highfor i in range(16):self.spi.write(b"\xff")# CMD0: init card; should return _R1_IDLE_STATE (allow 5 attempts)for _ in range(5):if self.cmd(0, 0, 0x95) == _R1_IDLE_STATE:breakelse:raise OSError("no SD card")# CMD8: determine card versionr = self.cmd(8, 0x01AA, 0x87, 4)if r == _R1_IDLE_STATE:self.init_card_v2()elif r == (_R1_IDLE_STATE | _R1_ILLEGAL_COMMAND):self.init_card_v1()else:raise OSError("couldn't determine SD card version")# get the number of sectors# CMD9: response R2 (R1 byte + 16-byte block read)if self.cmd(9, 0, 0, 0, False) != 0:raise OSError("no response from SD card")csd = bytearray(16)self.readinto(csd)if csd[0] & 0xC0 == 0x40: # CSD version 2.0self.sectors = ((csd[8] << 8 | csd[9]) + 1) * 1024elif csd[0] & 0xC0 == 0x00: # CSD version 1.0 (old, <=2GB)c_size = csd[6] & 0b11 | csd[7] << 2 | (csd[8] & 0b11000000) << 4c_size_mult = ((csd[9] & 0b11) << 1) | csd[10] >> 7self.sectors = (c_size + 1) * (2 ** (c_size_mult + 2))else:raise OSError("SD card CSD format not supported")# print('sectors', self.sectors)# CMD16: set block length to 512 bytesif self.cmd(16, 512, 0) != 0:raise OSError("can't set 512 block size")# set to high data rate now that it's initialisedself.init_spi(baudrate)def init_card_v1(self):for i in range(_CMD_TIMEOUT):self.cmd(55, 0, 0)if self.cmd(41, 0, 0) == 0:self.cdv = 512# print("[SDCard] v1 card")returnraise OSError("timeout waiting for v1 card")def init_card_v2(self):for i in range(_CMD_TIMEOUT):time.sleep_ms(50)self.cmd(58, 0, 0, 4)self.cmd(55, 0, 0)if self.cmd(41, 0x40000000, 0) == 0:self.cmd(58, 0, 0, 4)self.cdv = 1# print("[SDCard] v2 card")returnraise OSError("timeout waiting for v2 card")def cmd(self, cmd, arg, crc, final=0, release=True, skip1=False):self.cs(0)# create and send the commandbuf = self.cmdbufbuf[0] = 0x40 | cmdbuf[1] = arg >> 24buf[2] = arg >> 16buf[3] = arg >> 8buf[4] = argbuf[5] = crcself.spi.write(buf)if skip1:self.spi.readinto(self.tokenbuf, 0xFF)# wait for the response (response[7] == 0)for i in range(_CMD_TIMEOUT):self.spi.readinto(self.tokenbuf, 0xFF)response = self.tokenbuf[0]if not (response & 0x80):# this could be a big-endian integer that we are getting herefor j in range(final):self.spi.write(b"\xff")if release:self.cs(1)self.spi.write(b"\xff")return response# timeoutself.cs(1)self.spi.write(b"\xff")return -1def readinto(self, buf):self.cs(0)# read until start byte (0xff)for i in range(_CMD_TIMEOUT):self.spi.readinto(self.tokenbuf, 0xFF)if self.tokenbuf[0] == _TOKEN_DATA:breaktime.sleep_ms(1)else:self.cs(1)raise OSError("timeout waiting for response")# read datamv = self.dummybuf_memoryviewif len(buf) != len(mv):mv = mv[: len(buf)]self.spi.write_readinto(mv, buf)# read checksumself.spi.write(b"\xff")self.spi.write(b"\xff")self.cs(1)self.spi.write(b"\xff")def write(self, token, buf):self.cs(0)# send: start of block, data, checksumself.spi.read(1, token)self.spi.write(buf)self.spi.write(b"\xff")self.spi.write(b"\xff")# check the responseif (self.spi.read(1, 0xFF)[0] & 0x1F) != 0x05:self.cs(1)self.spi.write(b"\xff")return# wait for write to finishwhile self.spi.read(1, 0xFF)[0] == 0:passself.cs(1)self.spi.write(b"\xff")def write_token(self, token):self.cs(0)self.spi.read(1, token)self.spi.write(b"\xff")# wait for write to finishwhile self.spi.read(1, 0xFF)[0] == 0x00:passself.cs(1)self.spi.write(b"\xff")def readblocks(self, block_num, buf):nblocks = len(buf) // 512assert nblocks and not len(buf) % 512, "Buffer length is invalid"if nblocks == 1:# CMD17: set read address for single blockif self.cmd(17, block_num * self.cdv, 0, release=False) != 0:# release the cardself.cs(1)raise OSError(5) # EIO# receive the data and release cardself.readinto(buf)else:# CMD18: set read address for multiple blocksif self.cmd(18, block_num * self.cdv, 0, release=False) != 0:# release the cardself.cs(1)raise OSError(5) # EIOoffset = 0mv = memoryview(buf)while nblocks:# receive the data and release cardself.readinto(mv[offset : offset + 512])offset += 512nblocks -= 1if self.cmd(12, 0, 0xFF, skip1=True):raise OSError(5) # EIOdef writeblocks(self, block_num, buf):nblocks, err = divmod(len(buf), 512)assert nblocks and not err, "Buffer length is invalid"if nblocks == 1:# CMD24: set write address for single blockif self.cmd(24, block_num * self.cdv, 0) != 0:raise OSError(5) # EIO# send the dataself.write(_TOKEN_DATA, buf)else:# CMD25: set write address for first blockif self.cmd(25, block_num * self.cdv, 0) != 0:raise OSError(5) # EIO# send the dataoffset = 0mv = memoryview(buf)while nblocks:self.write(_TOKEN_CMD25, mv[offset : offset + 512])offset += 512nblocks -= 1self.write_token(_TOKEN_STOP_TRAN)def ioctl(self, op, arg):if op == 4: # get number of blocksreturn self.sectors

test.py

import machine, sd, os from machine import SPI,Pin spitf=SPI(baudrate=2000000, sck=Pin(18), mosi=Pin(19),miso=Pin(23)) tf = sd.SDCard(spitf,Pin(5)) os.mount(tf, '/sd') os.listdir('/')

然后直接在thonny里面發現目錄里多了一個sd文件夾，他就是我們親愛的sd卡了，親測上傳下載文件都正常。

總結

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