SanDisk SD-ROM, Product Manual

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3.3.4 Card Status Register
The Card Status Register (CSR) transmits the card's status information to the host. The CSR is
defined in Section 4.10.1 in the SDA Physical Layer Specification, Version 2.00.
3.3.5 SD Status Register
The SD Status Register (SSR) contains status bits that are related to the SD Card proprietary
features and may be used for future applications. The SD Status structure is described in
Section 4.10.2 in the SDA Physical Layer Specification, Version 2.00.
3.3.6 Relative Card Address Register
The 16-bit Relative Card Address (RCA) Register carries the card address published by the
card during the card identification process. Refer to Section 5.4 in the SDA Physical Layer
Specification, Version 2.00 for more information.
3.3.7 Operation Conditions Register
The Operation Conditions Register (OCR) stores a card's VDD voltage profile. Refer to
Section 5.1 of the SDA Physical Layer Specification, Version 2.00 for more information.
3.4 Bus Topology
The family of SanDisk SD products supports two communication protocols: SD and SPI. For
more details, refer to Section 3.5 of the SDA Physical Layer Specification, Version 2.00. Section
6 of the specification contains a bus circuitry diagram for reference.
NOTE: SD Card pin assignments are provided by the SDA Physical Layer Specification, Version
2.00; refer to Section 8.2.
SD Bus Mode Pin Assignment SPI Bus Mode Pin Assignment
#
Function I/O Type Description Function I/O Type Description
1 CD/DAT3
1,2
push-pull
Card Detect /
Data [bit 3]
CS
1
input
Chip Select (active low)
2 CMD push-pull
Command /
Response
DataIn
input Host-to-Card
commands and data
3 VSS1
supply Supply Ground
VSS1
supply Supply Ground
4 VDD
supply Supply Voltage
VDD
supply Supply Voltage
5 CLK input Clock SCLK input Clock
6 VSS2
supply Supply Ground
VSS2
supply Supply Ground
7 DAT0 push-pull Data [bit 0] DataOut output
Card-to-Host Data and
Status
8 DAT1
2
push-pull Data [bit 1] RSV Reserved
9 DAT2
2
push-pull Data [bit 2] RSV Reserved
Notes:
1. At power up this line has a 50KOhm pullup enabled in the card. This resistor serves two
functions: Card Detection and Mode Selection. For Mode Selection, the host can drive the
line high or let it be pulled high to select SD mode. If the host wants to select SPI mode it
should drive the line low. For Card detection, the host detects that the line is pulled high.
This pull-up should be disconnected by the user, during regular data transfer, with the
SET_CLR_CARD_DETECT (ACMD42) command.
2. The extended DAT lines (DAT1-DAT3) are input on power up. They start to operate as DAT
lines after the SET_BUS_WIDTH command. It is the responsibility of the host designer to
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