adafruit_sdcard - SD card over SPI driver

CircuitPython 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.

• Author(s): Scott Shawcroft

Implementation Notes

Hardware:

• Adafruit MicroSD card breakout board+ (Product ID: 254)

• Adafruit Assembled Data Logging shield for Arduino (Product ID: 1141)

• Adafruit Feather M0 Adalogger (Product ID: 2796)

• Adalogger FeatherWing - RTC + SD Add-on For All Feather Boards (Product ID: 2922)

Software and Dependencies:

• Adafruit CircuitPython firmware for the ESP8622 and M0-based boards: https://github.com/adafruit/circuitpython/releases

• Adafruit’s Bus Device library: https://github.com/adafruit/Adafruit_CircuitPython_BusDevice

class adafruit_sdcard.SDCard(spi: SPI, cs: DigitalInOut, baudrate: int = 1320000)

Controls an SD card over SPI.

Parameters:

• spi (SPI) – The SPI bus

• cs (DigitalInOut) – The chip select connected to the card

• baudrate (int) – The SPI data rate to use after card setup

Example usage:

import busio
import storage
import adafruit_sdcard
import digitalio
import os
import board

spi = busio.SPI(SCK, MOSI, MISO)
cs = digitalio.DigitalInOut(board.SD_CS)
sdcard = adafruit_sdcard.SDCard(spi, cs)
vfs = storage.VfsFat(sdcard)
storage.mount(vfs, '/sd')
os.listdir('/sd')

count() → int

Returns the total number of sectors.

Returns:

The number of 512-byte blocks

Return type:

int

readblocks(start_block: int, buf: array | bytearray | memoryview | rgbmatrix.RGBMatrix | ulab.numpy.ndarray) → int

Read one or more blocks from the card

Parameters:

• start_block (int) – The block to start reading from

• buf (WriteableBuffer) – The buffer to write into. Length must be multiple of 512.

writeblocks(start_block: int, buf: array | bytearray | bytes | memoryview | rgbmatrix.RGBMatrix | ulab.numpy.ndarray) → int

Write one or more blocks to the card

Parameters:

• start_block (int) – The block to start writing to

• buf (ReadableBuffer) – The buffer to write into. Length must be multiple of 512.

adafruit_sdcard.calculate_crc(message: array | bytearray | bytes | memoryview | rgbmatrix.RGBMatrix | ulab.numpy.ndarray) → int

Calculate the CRC of message[0:5], using a precomputed table in CRC_TABLE.

Parameters:

message (bytearray) – Where each index is a byte