HB28E016/D032/D064/B128MM2
13
SPEC_VERS
Defines the Spec version supported by the card. It includes the commands set definition and the definition
of the card responses. The card identification procedure is compatible for all spec versions!
SPEC Version
SPEC_VERS
System specification version number
“
0011
”
System specification version 3.1
The Spec version of these Hitachi MultiMediaCards is related to the “MultiMediaCard system
specification, Version 3.1”. The parameter SPEC_VERS has permanently the value “0011”.
TAAC
Defines the asynchronous data access time:
TAAC Access Time Definition
TAAC bit
Description
Values
2:0
ime exponent
0 = 1 ns, 1 = 10 ns, 2 = 100 ns, 3 = 1
μ
s, 4 = 10
μ
s,
5 = 100
μ
s, 6 = 1 ms, 7 = 10 ms
6:3
ime mantissa
0 = reserved, 1 = 1.0, 2 = 1.2, 3 = 1.3, 4 = 1.5,
5 = 2.0, 6 = 2.5, 7 = 3.0, 8 = 3.5, 9 = 4.0, A = 4.5,
B = 5.0, C = 5.5, D = 6.0, E = 7.0, F = 8.0
7
eserved
always
‘
0
’
The value for the asynchronous delay for these Hitachi MultiMediaCards is 1 ms. The coded TAAC value
is 0x0E (= 1 ms). For more details refer to Chapter “Operating Characteristics”.
NSAC
Defines the worst case for the synchronous data access time. The unit for NSAC is 100-clock cycles.
Therefore, maximum value for the data access time is 25.6k clock cycles. The total access time N
AC
as
expressed in the Table “Timing Values” is the sum of both TAAC and NSAC. It has to be computed by the
host for the actual clock rate. The read access time should be interpreted as a typical delay for the first data
bit of a data block or stream. The value of NSAC for these Hitachi MultiMediaCards is 0x01 (100-clock
cycles). For more details refer to Chapter “Operating Characteristics”.