Hardware Reference
In-Depth Information
The various SD card connections are used in different ways, as documented by the
Table
8-2
mnemonics in the columns I/O and Logic. Table
8-3
is a legend for these and
also applies to later Tables 10-4 and 10-5.
Table 8-3.
Legend for I/O and Logic
Notation
Meaning
Notes
I
Input
Relative to card
O
Output
I/O
Input or output
PP
Push/pull logic
OD
Open drain
S
Power supply
NC
Not connected
Or logic high
1-bit SD Mode
Table
8-4
lists the pins and functions of the SD card when it is in 1-bit SD mode. The
data traverses pin 7 (DAT0) while the clock is supplied on pin 5. Pin 2 is used to send
commands and receive responses. This mode uses a proprietary transfer format.
Table 8-4.
1-bit SD Mode
Pin
Name
I/O
Logic
Description
1
NC
No connection
2
CMD
I/O
PP/OD
Command/response
3
VSS
S
S
Ground
4
VDD
S
S
Power
5
CLK
I
PP
Clock
6
VSS
S
S
Ground
7
DAT0
I/O
PP
Data 0
8
NC
NC
Memory cards
nIRQ
O
OD
SDIO cards
9
NC
No connection
