39.7 Bus Topology

Figure 39-3. High Speed MultiMedia Memory Card Bus Topology

The High Speed MultiMedia Card communication is based on a 13-pin serial bus interface. It has three communication lines and four supply lines.

Table 39-2. Bus Topology
Pin Number	Name	Type⁽¹⁾	Description	HSMCI Pin Name⁽²⁾ (Slot z)
1	DAT[3]	I/O/PP	Data	MCDz3
2	CMD	I/O/PP/OD	Command/response	MCCDz
3	VSS1	S	Supply voltage ground	VSS
4	VDD	S	Supply voltage	VDD
5	CLK	O	Clock	MCCK
6	VSS2	S	Supply voltage ground	VSS
7	DAT[0]	I/O/PP	Data 0	MCDz0
8	DAT[1]	I/O/PP	Data 1	MCDz1
9	DAT[2]	I/O/PP	Data 2	MCDz2

Note:

I: Input, O: Output, PP: Push/Pull, OD: Open Drain, S: Supply
When several HSMCI (x HSMCI) are embedded in a product, MCCK refers to HSMCIx_CK, MCCDA to HSMCIx_CDA, MCDAy to HSMCIx_DAy.

Figure 39-4. MMC Bus Connections (One Slot)

Figure 39-5. SD Memory Card Bus Topology

The SD Memory Card bus includes the signals listed in the table below.

Table 39-3. SD Memory Card Bus Signals
Pin Number	Name	Type⁽¹⁾	Description	HSMCI 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	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

Note:

I: input, O: output, PP: Push Pull, OD: Open Drain.
When several HSMCI (x HSMCI) are embedded in a product, MCCK refers to HSMCIx_CK, MCCDA to HSMCIx_CDA, MCDAy to HSMCIx_DAy.

Figure 39-6. SD Card Bus Connections with One Slot

When the HSMCI is configured to operate with SD memory cards, the width of the data bus can be selected in the HSMCI_SDCR. 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 High Speed MultiMedia cards, only the data line 0 is used. The other data lines can be used as independent PIOs.