SanDisk SDSDH-1024 Product Manual - Page 23

SD Bus Topology

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Revision 2.2 Chapter 3 - SD Card Interface Description SD Card Product Manual 3.2 SD Bus Topology The SD Memory Card bus has six communication lines and three supply lines. • CMD • DAT0-3 • CLK • VDD • VSS[1:2] The description of each signal is contained in Table 3-3. Table 3-3 MMC Bus Signal Descriptions Name CMD DAT0-3 CLK VDD VSS [1:2] Description Command is a bi-directional signal. Host and card drivers are operating in pushpull mode. Data lines are bi-directional signals. Host and card drivers are operating in pushpull mode. Clock is a host to card signal. CLK operates in push-pull mode. Power supply line for all cards. Two ground lines. Figure 3-2 shows the bus topology of several cards with one host in SD Bus mode. Figure 3-2 SD Card System Bus Topology HOST CLK Vdd Vss D0-3(A), CMD(A) CLK Vdd Vss D0-D3, CMD SD Memory Card (A) D0-3(B), CMD(B) CLK Vdd Vss D0-D3, CMD SD Memory Card (B) D0-3(C) CMD(C) CLK Vdd Vss D0, CS, CMD MultiMediaCard (C) D1&D2 Not Connected © 2004 SanDisk Corporation 3-3 12/08/04

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Chapter 3 – SD Card Interface Description
Revision 2.2
SD Card Product Manual
© 2004 SanDisk Corporation
3-3
12/08/04
3.2
SD Bus Topology
The SD Memory Card bus has six communication lines and three supply lines.
•
CMD
•
DAT0-3
•
CLK
•
VDD
•
VSS[1:2]
The description of each signal is contained in Table 3-3.
Table 3-3
MMC Bus Signal Descriptions
Name
Description
CMD
Command is a bi-directional signal.
Host and card drivers are operating in push-
pull mode.
DAT0-3
Data lines are bi-directional signals. Host and card drivers are operating in push-
pull mode.
CLK
Clock is a host to card signal.
CLK operates in push-pull mode.
V
DD
Power supply line for all cards.
V
SS
[1:2]
Two ground lines.
Figure 3-2 shows the bus topology of several cards with one host in SD Bus mode.
Figure 3-2
SD Card System Bus Topology
SD Memory
Card (A)
CLK
Vdd
Vss
D0-D3, CMD
SD Memory
Card (B)
CLK
Vdd
Vss
D0-D3, CMD
MultiMediaCard
(C)
CLK
Vdd
Vss
D0, CS, CMD
CLK
Vdd
Vss
D0-3(A),
CMD(A)
D0-3(B),
CMD(B)
D0-3(C)
CMD(C)
HOST
D1&D2 Not
Connected