User Manual

SPI Protocol Definition
TriFlash with SD Interface Product Manual (Preliminary), Rev. 1.2 © 2002/2003 SANDISK CORPORATION
5-3
From
Host to
Card
From
Card to
Host
Data Error Token
from Card to Host
Next
Command
DataIn
DataOut
Command
Response
Command
Data Error
Figure 5-2. Read Operation—Data Error
In the case of a Multiple Block Read operation, every transferred block has a 16-bit CRC suffix. The Stop
Transmission command (CMD12) will actually stop the data transfer operation (the same as in SD Bus mode).
From
host to
card(s)
DataIn
DataOut
Command
Data from
card to host
Command
Response
From
card to
host
Response
Data block crc Data block crc
From
card to
host
Stop
Transmission
Command
Figure 5-3. Multiple Block Read Operation
5.1.4. Data Write
In SPI mode, the TriFlash supports single block or multiple block write operations. Upon reception of a valid write
command (CMD24 or CMD25), the device will respond with a response token and will wait for a data block to be
sent from the host. CRC suffix and start address restrictions are identical to the read operation (refer to Figure 5-4).
The only valid block length, however, is 512 bytes. Setting a smaller block length will cause a write error on the
next write command.
From
Host to
Card
From
Card to
Host
DataIn
DataOut
Command
Data From
Host to Card
Data_
Response
Busy
Data
Response
and Busy
From Card
Response
Data Block
Start
Block
Token
New Command
from Host
Command
Figure 5-4. Single Block Write Operation
Every data block has a prefix or ‘start block’ token (one byte). After a data block is received the device will respond
with a data-response token, and if the data block is received with no errors, it will be programmed. As long as the
device is busy programming, a continuous stream of busy tokens will be sent to the host (effectively holding the
dataOut line low).