MultiMediaCardTM
4.10.12 Responses
There are several types of response tokens. As in the MultiMediaCard mode, all are transmitted MSB
first:
* Format R1
This response token is sent by the card after every command with the exception of SEND_STATUS
commands. It is one byte long, and the MSB is always set to zero. The other bits are error indications,
an error being signaled by a ‘1’. The structure of the R1 format is given in Figure “R1 Response
Format”. The meaning of the flags is defined as following
- In idle state: The card is in idle state and running the 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.
Figure 4-9 R1 Response Format
Format R1b
This response token is identical to the 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
the card is ready for the next command.
Format R2
This response token is two bytes long and sent as a response to the SEND_STATUS command. The
format is given in Figure “R2 Response Format”.
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