SPI Protocol Definition
SanDisk Secure Digital (SD) Card Product Manual, Rev. 1.9 © 2003 SANDISK CORPORATION
5-13
5.2.3.1. Format R1
This response token is sent by the card after every command with the exception of SEND_STATUS commands. It
is 1 byte long, the MSB is always set to zero and the other bits are error indications. A ‘1’ signals error.
•
In idle state—The card is in idle state and running initializing process.
•
Erase reset—An erase sequence was cleared before executing because an out of erase sequence
command was received.
•
Illegal command—An illegal command code was detected.
•
Communication CRC error—The CRC check of the last command failed.
•
Erase sequence error—An error in the sequence of erase commands occurred.
•
Address error—A misaligned address, which did not match the block length was used in the
command.
•
Parameter error—The command’s argument (e.g., address, block length) was out of the allowed range
for this card.
The structure of the R1 format is shown in Figure 5-7.
7
I n I d l e S t a t e
E r a s e R e s e t
I l l e g a l C o m m a n d
C o m C R C E r r o r
E r a s e _ S e q _ E r r o r
0
0
A d d r e s s E r r o r
P a r a m e t e r E r r o r
Figure 5-7. R1 Response Format
5.2.3.2. Format R1b
This response token is identical to R1 format with the optional addition of the busy signal. The busy signal token
can be any number of bytes. A zero value indicates card is busy. A non-zero value indicates card is ready for the
next command.
5.2.3.3. Format R2
This 2-bytes long response token is sent by the card as a response to the SEND_STATUS command. The format of
the R2 status is shown in Figure 5-8.
