SanDisk SD128, SD-ROM, SD064, SD032 manual Bus Topology, Card Status Register, SD Status Register

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/DAT31,2	push-pull		Card Detect /		CS1		input	Chip Select (active low)
						Data [bit 3]
2			CMD	push-pull		Command /		DataIn		input	Host-to-Card
						Response					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		DAT12		push-pull	Data [bit 1]		RSV				Reserved
9		DAT22		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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