MultiMediaCard
TM
57
Sep.22.2005
Revision 0.3
Low bus category classes (26MHz clock with 4bit data bus operation)
2.4 MB/s Class A
3.0 MB/s Class B
4.5 MB/s Class C
6.0 MB/s Class D
9.0 MB/s Class E
Mid bus category classes (26MHz clock with 8bit data bus or 52MHz clock with 4bit data bus operation):
12.0 MB/s Class F
15.0 MB/s Class G
18.0 MB/s Class H
21.0 MB/s Class J
High bus category classes (52MHz clock with 8bit data bus operation):
24.0 MB/s Class K
30.0 MB/s Class M
36.0 MB/s Class O
42.0 MB/s Class R
48.0 MB/s Class T
The performance values for both write and read accesses are stored into the EXT_CSD register for electrical reading (see
chapter 5.5.4 on page 32). Only the defined values and classes are allowed to be used.
6.6.2 Absolute Minimum
Absolute minimum read and write access performance which all MMCplus and MMCmobile cards has to fullfill is 2.4MB/s.
This is the Class A.
6.6.3 Measurement of the Performance
The procedure for the measurement of the performance of the card is defined in detail in the Compliance Documentation.
Initial state of the memory in prior to the test is: filled with random data. The test is performed by writing/reading a 64kB
chunk of data to/from random logical addresses (aligned to physical block boundaries)of the card. A predefined multiple
block write/read is used with block count of 128 (64kB as 512B blocks are used). The performance is calculated as aver-
age out of several 64kB accesses.
Same test is performed with all applicable clock frequency and bus width options as follows:
52MHz, 8bit bus (if 52MHz clock frequency is supported by the card)
52MHz, 4bit bus (if 52MHz clock frequency is supported by the card)
26MHz, 8bit bus
26MHz, 4bit bus
In case the minimum performance of the card exceeds the physical limit of one of the above mentioned options the card
has to also fulfill accordingly the performance criteria as defined in
MIN_PERF_a_b_ff
in chapter 5.5.4 on page 32