 7 pin MM-card special connector at the card | The MultiMedia Card communication is based on serial bus designed to operate in a low voltage range. For compatibility to existing controllers the cards may offer,in addition to the MultiMedia Card mode, an alternate communication protocol which is based on the SPI standard. | Pin | Signal | Description |
| 1 | RSV NC | Not connected or Always “1” (data 3?) |
| 2 | CMD I/O | Command/Response |
| 3 | VSS1 S | Supply Voltage Ground |
| 4 | VDD S | Supply Voltage |
| 5 | CLK I | Clock |
| 6 | VSS2 S | Supply Voltage Ground |
| 7 | DAT0 I/O | PP Data 0 |
- CLK - with each cycle of this signal an one bit transfer on the command and data lines is done. The frequency may vary between 0-20MHz.
- CMD - is a bidirectional command channel used for card initialization and data transfer commands.
- DAT - is a bidirectional data channel. The DAT signal operates in push-pull mode. Only one card or the host is driving this signal at a time.
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