Product manual
4-17 SanDisk miniSD Card Product Manual, Rev. 1.1 © 2003 SANDISK CORPORATION
4.7. Error Conditions
The following sections provide valuable information on error conditions.
4.7.1. CRC and Illegal Command
CRC bits protect all commands. If the addressed miniSD Card’s CRC check fails, the card does not respond and the
command is not executed. The miniSD Card does not change its state, and COM_CRC_ERROR bit is set in the
status register.
Similarly, if an illegal command has been received, a miniSD Card shall not change its state, shall not respond and
shall set the ILLEGAL_COMMAND error bit in the status register. Only the non-erroneous state branches are
shown in the state diagrams (Figure 5-7 and Figure 5-8). Table 5-11 contains a complete state transition description.
There are different kinds of illegal commands:
• Commands belonging to classes not supported by the miniSD Card (e.g., write commands in read-only
cards).
• Commands not allowed in the current state (e.g., CMD9 in Transfer State).
• Commands not defined (e.g., CMD5).
4.7.2. Read, Write and Erase Time-out Conditions
Times after which a time-out condition for Read operations occur are (card independent) either 100 times longer
than the typical access times for these operations given below or 100ms. The times after which a time-out condition
for Write/Erase operations occur are (card independent) either 100 times longer than the typical program times for
these operations given below or 250ms. A card shall complete the command within this time period, or give up and
return an error message. If the host does not get any response with the given time out it should assume the card is
not going to respond anymore and try to recover (e.g., reset the card, power cycle, reject). The typical access and
program times are defined as follows:
Read
The read access time is defined as the sum of the two times given by the CSD parameters TAAC and NSAC. These
card parameters define the typical delay between the end bit of the read command and the start bit of the data block.
Write
The R2W_FACTOR field in the CSD is used to calculate the typical block program time obtained by multiplying
the read access time by this factor. It applies to all write/erase commands (e.g., SET(CLEAR)_WRITE_PROTECT,
PROGRAM_CSD(CID) and the block write commands).
Erase
The duration of an erase command will be (order of magnitude) the number of write blocks (WRITE_BL) to be
erased multiplied by the block write delay.