4.6.1. Card interface description

Figure 4.12 shows the card interface.

Figure 4.12. MMC interface description

Table 4.12 shows the assignment of the MMCI signals.

Table 4.12. MMC interface signals

Signal nameHDRB Function

Controls card power:

LOW = power ON

HIGH = power OFF

MCI_8F12not used
MCI_9F13not used
nCARDINRouted to PLD Card insertion interrupt
WPROTRouted to PLD Write protect status of MMC.

The MMC socket (J11) provides nine pins that connect with contacts on the card when it is inserted into the socket. Figure 4.13 shows the pin numbering and signal assignment, with pin 9 next to pin 1 and pins 7 and 8 spaced more closely together than the other pins. (The 9-way socket is compatible with SD cards, however MMC only uses 7 of the 9 pins.) In addition, the socket contains two switches that are operated by inserting or removing the card. These are used to provide signaling on the nCARDIN and WPROT signals.

Figure 4.13. MMC card socket pin numbering

MMC cards use seven pins. Figure 4.14 shows an MMC card, with the contacts face up.

Figure 4.14. MMC card

Insert and remove the card as follows:


Insert the card into the socket with the contacts face down. Cards are normally labeled on the top surface with an arrow to indicate correct insertion.


Remove the card by gently pressing it into the socket. It springs back and can be removed. Removing the card in this way ensures that the card detection switches within the socket operate correctly.

The connector J9 enables you to access the signals for debugging or to route them to an off-PCB card socket. The pinout of J9 is shown in Figure 4.15.

Figure 4.15. J9 pinout

Copyright © 2002 ARM Limited. All rights reserved.ARM DUI 0159B