SD Storage

SD Card Registers

Document SD Card registers.
Bit Filed Description Addend
31 Card Power Up Status This bit is set if the card power up procedure has been finished.
30 Card Capcity Status * 0 - SDSC
* 1 - SDHC/SDXC
29 UHS-II Card Status * 0 - non UHS-II Card
* 1 - UHS-II Card
28 : 25 Resv
24 Switching to 1.8V Accepted * 0 - non UHS-I Card
* 1 - UHS-I Card
23 3.5 ~ 3.6V VDD voltage range supported by the SD card.
22 3.4 ~ 3.5V VDD voltage range supported by the SD card.
21 3.3 ~ 3.4V VDD voltage range supported by the SD card.
20 3.2 ~ 3.3V VDD voltage range supported by the SD card.
19 3.1 ~ 3.2V VDD voltage range supported by the SD card.
18 3.0 ~ 3.1V VDD voltage range supported by the SD card.
17 2.9 ~ 3.0V VDD voltage range supported by the SD card.
16 2.8 ~ 2.9V VDD voltage range supported by the SD card.
15 2.7 ~ 2.8V VDD voltage range supported by the SD card.
14 : 0 Resv

Card Capcity Status (CCS)

CCS field is valid after bit 31 is set. When CCS in OCR is cleared, it indicates that the card is a SDSC. The arguments (data addresses) for the following commands are in bytes. Otherwise, they are in units of 512 bytes.

  • CMD17/CMD18
  • CMD24/CMD25
  • CMD28/CMD29/CMD30
  • CMD32/CMD33
Field Bit Description Addend
C_SIZE 73:62 Used to compute the device capacity for devices up to 2 GB of density.
Field Byte Description Addend
SEC_COUNT 215:212 Used to compute the device capacity for devices greater than 2 GB of density.

Calculating SD Density

Densities Greater than 2GB

Device density = SEC_COUNT * 512B

C_SIZE should be set to 0xfff.
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