SpiSD

This module handles operations on Standard Capacity and High Capacity SD Cards (SDSC, SDHC) through Spi protocol. The following operations are allowed:

  • read/write single block, with block address specified through SDSC or SDHC convention;
  • read/write multiple blocks, with block address specified through SDSC or SDHC convention;
  • generic read/write data, with block address specified through SDHC convention for both SDCS and SDHC cards;
  • read cid register.

Block size is set by default to 512 bytes.

Address conventions:

  • SDSC convention allows to select a block through its first byte location in byte address (example: for a block size of 512 bytes, second block will be addressed 0x200);
  • SDHC convention allows to select a block through its block address (example: 2nd block address (starting from 0th block) is simply 0x2)

SpiSD class

class SpiSD(drvname, cs, clock=1000000)

Initialize an SD card specifying its:

  • MCU SPI circuitry drvname (one of SPI0, SPI1, ... check pinmap for details);
  • chip select pin cs;
  • clock clock, default at 1MHz

The instance attribute hc is set to 1 if the card is recognized as an SDHC, to 0 otherwise.

single_block_read(addr)

Read a single block at address addr, following SDSC or SDHC address convention depending on used card.

multiple_blocks_read(addr, n)

Read n blocks starting from address addr, following SDSC or SDHC address convention depending on used card.

read_data(addr, n)

Read n blocks starting from address addr, SDHC address convention is used.

single_block_write(addr, data)

Write a single block at address addr, following SDSC or SDHC address convention depending on used card. data must be a 512-byte long bytearray.

multiple_blocks_write(addr, data)

Write data starting from address addr, following SDSC or SDHC address convention depending on used card.

Two formats allowed for data:

  • bytearray with a len multiple of 512 bytes.

  • list of 512-byte long bytearrays, where each bytearray inside data list contains data for a single block:

    block_1 = bytearray(0x200)
block_2 = bytearray(0x200)
...
[ block_1 , block_2 , ... ]
write_data(addr, data)

Write data starting from address addr, SDHC address convention is used.

data format is defined as in multiple_blocks_write() .

read_cid()

Read 16-byte long cid register value.