Product manual

5-5 SanDisk miniSD Card Product Manual, Rev. 1.1 © 2003 SANDISK CORPORATION
Figure 5-6. “No Data” Operations
5.1.6. Read CID/CSD Registers
Unlike the SD Bus protocol (where the register contents are sent as a command response), reading the contents of
the CSD and CID registers in SPI mode is a simple read-block transaction. The card will respond with a standard
response token followed by a data block of 16 bytes suffixed with a 16-bit CRC.
The data time out for the CSD command cannot be set to the card TAAC since this value is stored in the CSD.
Therefore, the standard response time-out value (N
CR
) is used for read latency of the CSD register.
5.1.7. Reset Sequence
The miniSD Card requires a defined reset sequence. After power on reset or CMD0 (software reset), the card enters
an idle state. At this state, the only legal host commands are CMD1 (SEND_OP_COND), ACMD41
(SD_SEND_OP_COND), CMD59 (CRC_ON_OFF) and CMD58 (READ_OCR).
The host must poll the card (by repeatedly sending CMD1) until the ‘in-idle-state’ bit in the card response indicates
(by being set to 0) that the card completed its initialization processes and is ready for the next command.
In SPI mode, however, CMD1 has no operands and does not return the contents of the OCR register. Instead, the
host can use CMD58 (SPI Mode Only) to read the OCR register. It is the responsibility of the host to refrain from
accessing cards that do not support its voltage range.
The use of CMD58 is not restricted to the initialization phase only, but can be issued at any time. The host must poll
the card (by repeatedly sending CMD1) until the ‘in-idle-state’ bit in the card response indicates (by being set to 0)
that the card has completed its initialization process and is ready for the next command.
5.1.8. Clock Control
The SPI bus clock signal can be used by the SPI host to set the cards to energy-saving mode or to control the data
flow (to avoid under-run or over-run conditions) on the bus. The host is allowed to change the clock frequency or
shut it down.
Command
DataIn
Response
From Host
to Card
From Host
to Card
DataOut
Command
Response
Busy
From Card
to Host
From Card
to Host