Rainbow Electronics AT91CAP9S250A - Manual (Page 763)

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6264A–CAP–21-May-07
AT91CAP9S500A/AT91CAP9S250A
The SD Memory Card bus includes the signals listed in Table 41-3 .
Notes: 1. I: input, O: output, PP: Push Pull, OD: Open Drain.
2. When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK, MCCDA
to MCIx_CDA, MCDAy to MCIx_DAy.
Figure 41-6. SD Card Bus Connections with One Slot
Note: When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK, MCCDA to MCIx_CDA MCDAy to MCIx_DAy.
When the MCI is configured to operate with SD memory cards, the width of the data bus can
be selected in the MCI_SDCR register. Clearing the SDCBUS bit in this register means that
the width is one bit; setting it means that the width is four bits. In the case of multimedia cards,
only the data line 0 is used. The other data lines can be used as independent PIOs.
41.7 MultiMedia Card Operations
After a power-on reset, the cards are initialized by a special message-based MultiMedia Card
bus protocol. Each message is represented by one of the following tokens:
• Command: A command is a token that starts an operation. A command is sent from the
host either to a single card (addressed command) or to all connected cards (broadcast
command). A command is transferred serially on the CMD line.
• Response: A response is a token which is sent from an addressed card or (synchronously)
from all connected cards to the host as an answer to a previously received command. A
response is transferred serially on the CMD line.
• Data: Data can be transferred from the card to the host or vice versa. Data is transferred
via the data line.
Table 41-3. SD Memory Card Bus Signals
Pin
Number
Name Type (1) Description
MCI Pin Name (2)
(Slot z)
1 CD/DAT[3] I/O/PP Card detect/ Data line Bit 3 MCDz3
2 CMD PP Command/response MCCDz
3 VSS1 S Supply voltage ground VSS
4 VDD S Supply voltage VDD
5 CLK I/O Clock MCCK
6 VSS2 S Supply voltage ground VSS
7 DAT[0] I/O/PP Data line Bit 0 MCDz0
8 DAT[1] I/O/PP Data line Bit 1 or Interrupt MCDz1
9 DAT[2] I/O/PP Data line Bit 2 MCDz2
2345
6
17
MCDA0 - MCDA3
MCCDA
MCCK
8
SD CARD
9