HB28E016/D032/D064/B128MM2
26
Read, Write and Erase Time-out Conditions
The times after which a time-out condition for read/write/erase operations occurs are (card independent) 10
times longer than the access/program times for these operations given below. A card shall complete the
command within this time period, or give up and return an error message. If the host does not get a
response within the defined 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, etc.). 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 (refer to Table “Card Specific Data (CSD)”). These card parameters define the typical delay
between the end bit
of the read command and the start bit of the data block. This number is card dependent
and should be used by the host to calculate throughput and the maximal frequency for stream read.
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). It should be
used by the host to calculate throughput and the maximal frequency for stream write.
Erase
The duration of an erase command will be (order of magnitude) the number of sectors to be erased
multiplied by the block write delay.