
Functional Overview
181
December 2003 Revised March 2005
SPRS231D
The main features of the MMC/SDIO2 module are:
Full compliance with MMC command/response sets as defined in the MMC standard specifications v.3.1
Full compliance with SD command/response sets as defined in the SD physical layer specifications v.1.0
Full compliance with SDIO command/response sets as defined in the SDIO card specification v1.0
Flexible architecture, allowing support for new command structure
Built-in 64-byte FIFO for buffered read or write
16-bit-wide access bus between MMC/SDIO2 interface and the local hosts to maximize bus throughput
Designed for low power
Wide interrupt capability
Programmable clock generation
Two DMA channels
OMAP5912 also support control signals to external level shifters. These signals are derived from the
direction control of the MMC_DAT0 and MMC_CMD I/O pads (one direction control per data bit line and
one direction control for the command line).
NOTE:
The MMC/SDIO2 clock is multiplexed between the 48-MHz clock (APLL output) and the system clock
(19.2 MHz or 12 MHz).
At reset, the MMC/SDIO2 clock selection is the system clock.
The MMC/SDIO2 module is routed at the OMAP5912 level. The OMAP5912 configuration selects only
the part of the interface which is required.
3.8.8 General-Purpose I/O (GPIO)
OMAP5912 includes 4 GPIO peripherals of 16 GPIO pins each. There are up to 64 shared GPIO pins. Each
GPIO pin is independently configurable as either input or output. If configured as input, each pin can be
configurable to generate an interrupt upon detection of its signal level change. As both the MPU and the DSP
can access the GPIO, consideration must be taken for its arbitration.
The general-purpose input/output (GPIO) peripheral can be used for the following types of applications:
Input/output data
Generation of an interrupt in active mode upon the detection of external events
Generation of a wake-up request in idle mode upon the detection of external events
3.8.9 32-kHz Synchro Counter
This is a 32-bit ordinary counter, clocked by the falling edge of the 32-kHz clock. It is reset while the Power
Up Reset (PWRON_RESET) primary I/O is active (main OMAP5912 reset), then on the rising edge of
PWRON_RESET (PWRON_RESET release), it starts to count indefinitely. When the highest value is reached,
it wraps back to zero and starts running again.
MPU and DSP have the capability to read the count value at higher frequency from the peripheral interface.
The MPU can read it from a 32-bit peripheral access, whereas the DSP can only access it through two
consecutive 16-bit accesses.