Secure Digital & MultiMedia Cards

Shown looking into card

No. MultiMedia™ (MM)
7 pin definition:		 Secure Digital™ (SD) 9 pin definition: No.
SD Mode SPI Mode
Name Type Name Type Name Type
    DAT2 I/O/PP Reserved 9
1 Reserved CD/DAT3 I/O/PP !CS I 1
2 CMD I/O/PP/OD CMD PP DI I 2
3 Vss1 (Supply Voltage Ground) 3
4 VDD (Supply Voltage) 4
5 Serial Clock Input 5
6 Vss2 (Supply Voltage Ground) 6
7 DAT0 I/O/PP DAT0 I/O/PP DO O/PP 7
  DAT1 I/O/PP Reserved 8

CMD: Command / Response
DAT0...3: Data lines 0 to 3
CD: Card Detect
!CS: Chip Select (Active Low)
DI, DO: Data In, Data Out (SPI signals)

S: power supply; I: input;
O: output using push-pull drivers; PP: I/O using push-pull drivers
OD: open drain; NC: not connected (or logic high)

http://www.sdcard.org/ are the official keepers of the spec, but don't have it for free download.

http://www.sandisk.com/oem_sd_memorycard.html

Notes

SD cards evolved from MM cards, and share most pins. The SD spec added a card detection signal to pin 1, the ability to use up to 4 data bits for higher data rates, and to work in SPI mode. If buying equipment, SD is preferable to MM, SmartMedia, or XD.

The voltage range covers 3 NiCd/NiMH cells (3V6), 2-cell alkaline cells (3V), or low voltage logic (3V3), but NOT 5V.

Pins 9 and 1 to 6 are on a 2.5 mm pitch, slightly smaller than the common 0.1" (2.54 mm) grid.
Pin 7 is 2.425 mm from Pin 6, and Pin 8 is 1.7 mm away from Pin 7.

The pin numbering for SD cards is correct, they really did put pin 9 next to pin 1.

Connections

SPI Mode

SPI
Master		     SPI
Slave
         
!CS --> 1 !CS
MOSI --> 2 MOSI
GND --- 3 GND
VCC --- 4 VCC
CLK --> 5 CLK
GND --- 6 GND
MISO <-- 7 MISO
       

SD Mode

SD
Master		     SD
Slave
d2 <-> 9   d2
CD/d3 <-> 1 !CD/d3
CMD --> 2 CMD
GND --- 3 GND
VCC --- 4 VCC
CLK --> 5 CLK
GND --- 6 GND
d0 <-> 7 d0
d1 <-> 8 d1

SD Card Electrical Characteristics

Figures from www.kingmax.com/product/storage/KDxxxSC.pdf, you should double check specs for your own card.
VCC = 2V7 to 3V6
Clock rate is up to 20 MHz.
Multiple cards can share clock and power rails but not data lines.

ABSOLUTE MAXIMUM RATINGS

The maximum rating is the limit value that must not be exceeded even at an instant. As long as you use the product within the maximum rating defined, no permanent damage will ever occur. However this does not guaranteed the normal logical operation.

Parameter Symbol Min. Max. Unit Note
Supply Voltage VCC -0. 3 4. 6 V ESD (contact Pads)-44KV
Storage Temperature TSTG -40 85 C  
Pull-up resistance for CMD RCMD 10 100 kOhm Prevent bus floating
Pull-up resistance for DAT RDAT
Signal Line Capacitance CL   250 pF Fpp <5 MHz, 21cards Bus
  1000 pF Fpp <20 MHz, 7cards
Signal Card Capacitance CCARD   10 pF  
Maximum Signal line Inductances     16 nH Fpp <20 MHz
Pull-up resistance inside card(Pin1) RDAT3 10 90 kOhm May be used for card detection SD card

Operating Range

Parameter Symbol Min. Max. Unit Note
Supply Voltage VCC 2.0 3.6 V Supply Voltage Specified in OCR Register 2.7 to 3.6
VInput Low Voltage VIL Vss-0. 3 0. 25x VCC V  
VInput High Voltage VIH 0. 625x VCC VCC +0. 3V V  
Output Low Voltage VOL 0. 125x VCC   V VIOL=100uA@VDD Min
Output High Voltage VOH 0. 75x VCC   V VIOH= -100uA@VDD Min
Input Leakage Current   -10 10 uA  
Output Leakage Current   -10 10 uA  
Minimum Supply current     150 uA At 0 Hz, 3.6 V Standby state
High Speed Supply current     80 mA At 25 MHz, 3.6 V
FPP   0 25 MHz CL<100 pF (7 Cards)
Clock Frequency identification Mode FOD 0 400 KHz CL<250 pF (21 Cards)
Clock Low time tWL 10   ns CL<100 pF(7 Cards)
Clock High time tWH
Clock Rise time tTLH
Clock Fall time tTLH
Clock Low time tWL 50   ns CL<250 pF(21 Cards)
Clock High time tWH
Clock Rise time tTLH
Clock Fall time tTLH
Input Set-up Time tISU 5   ns CMD, DAT Reference to CLK
Input Hold Time tIH
Output Set-up Time tOSU
Output Set-up Time tOH