Specifications

©Copyright 2001-2013 SD Group (Panasonic, SanDisk, Toshiba) and SD Card Association
Physical Layer Simplified Specification Version 4.10
132
5.7.2.2 Extension Register Write Command (Single Block)
Figure 5-7 shows definition of Write Extension Register Single Block Command (CMD49). Bus timing of
this command is equivalent to a single block write command (CMD24). The response type is R1. Data
block length is fixed to 512-byte length.
Figure 5-7 : Write Extension Register Single Block Command (CMD49)
Fields in the argument of CMD49:
MIO: Selection of Memory Space or I/O Space (0: Memory Space, 1: I/O Space)
There are two independent spaces; Memory Extension Register Space and I/O Extension
Register Space. Which space accessed is selected by this bit.
FNO: Function Number
Unique Function Number is assigned to each function. FNO helps host to distinguish functions
and enables card to check sequence of commands. Up to 15 functions may be assigned for
memory and up to 7 functions may be assigned for I/O.
MW: Mask Write Operation (0: Mask is disabled, 1: Mask is enabled)
On accessing Data Port, card ignores this field but host shall set this bit to 0. If access is not to
Data Port, this bit determines the meaning of LEN/MASK field.
If this bit is set to 0, LEN/MASK field is used to specify data length.
If this bit is set to 1, LEN/MASK field is used to specify mask data and data length is
considered as 1 byte. Destination in Extension Register is specified by FNO and ADDR. The
first byte in the data block is used for a write data. Bit operation between destination and write
data is dependent on mask data. If a mask bit is set to 0, a bit of the destination correspondent
stays unchanged. If a mask bit is set to 1, a bit of write data correspondent is written to the
destination.
ADDR: Address of Extension Register Space
Lower 9-bit is used as offset address in a page and upper 8-bit is used as page number. Up to
256 pages is addressable.
Length / Mask
Length (9-bit when MW=0 for Register Access)
000h: 1byte
001h: 2 bytes
002h: 3 bytes
............
1FFh: 512 bytes
Mask (lower 8-bit when MW=1 for Register Access)
Length is fixed to 1.
Each bit controls write operation
1: Data bits are written
0: Register bits stay unchanged
Mask Write Mode
0b: Mask Disabled (Length is set to 16-08)
1b: Mask Enabled (Mask is set to 15-08)
Length is fixed to 1.
Memory or I/O
0b: Memory Extension
1b: I/O Extension
16-0838-35
xxxx
FNO
34 33-17
17-bit
ADDR
x
MW
xxxxxxxxx
LEN/MASK
007-013945-404647
x
MIO
1xxxxxxx11000110
ECRC7INDEXTS
16-0838-35
xxxx
FNO
34 33-17
17-bit
ADDR
x
MW
xxxxxxxxx
LEN/MASK
007-013945-404647
x
MIO
1xxxxxxx11000110
ECRC7INDEXTS
Function No.
Memory Space (MIO=0 4-bit Bit38-35)
0000b: Function 0
0001b: Function 1
..............
1111b: Function 15
I/O Space (MIO=1 3-bit Bit38-36, Bit35=0)
000b: Function 0
001b: Function 1
..............
111b: Function 7
Address (17-bit)
There are two independent spaces; Memory Space (MIO=0)
and I/O Space (MIO=1) up to 128KB for each function.