MMC/SD Host Controller
7-130
Card Open Drain Mode (OD)
This bit (6) must be set to 1 if the MMC card bus is operating in open-drain
mode during the response phase to the command sent. Typically, during card
identification mode, the card is either in idle, ready or identification state. This
bit must be set for MMC card commands 1, 2, 3, and 40.
For SD card, this bit must always be kept low, because SD cards do not have
open drain capability.
-
0: Push/pull
-
1: Open drain
Value after reset is low.
Command Index (Cmd_index)
Binary encoded value (bits 5-0) from 0 to 63 specifying the command number
sent to the card.
-
000000: CMD0
-
000001: CMD1
-
…
-
111111: CMD63
Values after reset are low (all 6 bits).
The MMC argument low and high registers specify the 32-bit argument value
that is passed with the command. These registers must be initialized prior to
sending the command itself to the card (write action into the MMC_CMD regis-
ter). The only exception is for a command index specifying stuff bits in
arguments, which makes a write unnecessary.
Table 7–96. MMC Argument Low Register (MMC_ARGL)
Bit
Name
Description
15–0
ARG_low
Command argument bits [15:0]
Values after reset are low (all 16 bits).
Table 7–97. MMC Argument High Register (MMC_ARGH)
Bit
Name
Description
15–0
ARG_high
Command argument bits [31:16]
Values after reset are low (all 16 bits).