MMC/SD Host Controller
7-125
MPU Public Peripherals
7.12.6 MMC/SD Internal Pullups
There are internal pullups on the following pins:
-
MMC.CMD I/O pin
-
MMC.DAT[3:0] I/O pins
MMC cards work in open drain mode on the MMC.CMD line during the identifi-
cation phase, and more generally for broadcast MMC commands; con-
sequently, a pullup on the MMC.CMD line is needed.
When MMC.CMD and MMC.DAT[3:0] line work in push/pull mode, it is impor-
tant to prevent bus floating conditions. Consequently, pullups are needed.
These pullups are directly controlled by the MMC/SD host controller
(adp_rcmd_o and adp_rdat_o) and are only active when required, which
saves power.
Table 7–92 and Table 7–93 show activation conditions for the MMC.CMD and
MMC.DAT pullups.
Table 7–92. MMC_CMD Pullups
MMC_SD Host
Controller Status
MMC CARD Status
MMC_CMD Pullup
(Open Drain Mode)
MMC_CMD Pullup
(Push/Pull Mode)
Input
Input
Active
Active
Input
Output
Active
Disabled
Output
Input
Disabled
Disabled
Table 7–93. MMC_DAT Pullups
MMC_SD Host Controller Status
MMC CARD Status
MMC_DAT Pullup (Both Modes)
Input
Input
Active
Input
Output
Disabled
Output
Input
Disabled
In flash-SPI mode, when no data is on the MMC.CMD and MMC.DAT lines
(input and output of the flash), the pullups are disabled.