Local host or
DMA access
mmci_cmd
MMCi_DMA_TX
mmci_dat0
Buffer Level
Command
Data
Time
Buffer full
Buffer empty
BLEN
bytes
LH sends a
write command
DMA write access
(BLEN writes)
From host
to card
From card
to host
From host
to card
Write transfer active
MMCi.MMCHS_PSTATE[8]
WTA = 0x1
Request cleared
after first DMA
access
Data fully written
in the card
Data to be sent to
the card is fully
written in the buffer
Busy
Data
From card
to host
From host
to card
Response
Interrupt request
Command
complete IRQ
Transfer
complete IRQ
CRC
status
mmchs-019
Data
mmci_dat[7:1]
Public Version
www.ti.com
MMC/SD/SDIO Integration
Figure 24-19. DMA Transmit Mode
24.3.2.2 Interrupt Requests
Several internal module events can generate an interrupt. Each interrupt has a status bit, an interrupt
enable bit, and a signal status enable:
•
The status of each type of interrupt is automatically updated in the MMCi.
register; it
indicates which service is required.
•
The interrupt status enable bits of the MMCi.
register enable/disable the automatic update
of the MMCi.
register on an event-by-event basis.
•
The interrupt signal enable bits of the MMCi.
register enable/disable the transmission of
an interrupt request on the interrupt line MMCi_IRQ (from the MMC/SD/SDIOi host controller to the
MPU subsystem interrupt controller) on an event-by-event basis.
If an interrupt status is disabled in the MMCi.
register, then the corresponding interrupt request
is not transmitted, and the value of the corresponding interrupt signal enable in the MMCi.
register is ignored.
When an interrupt event occurs, the corresponding status bit is automatically set to 0x1 (the
MMC/SD/SDIOi host controller updates the status bit) in the MMCi.
register. If later a mask
is applied on the interrupt in the MMCi.
register, the interrupt request is deactivated.
When the interrupt source has not been serviced, if the interrupt status is cleared in the
MMCi.
register and the corresponding mask is removed from the MMCi.
register, the interrupt status is not asserted again in the MMCi.
register and the
MMC/SD/SDIOi host controller does not transmit an interrupt request.
3381
SWPU177N – December 2009 – Revised November 2010
MMC/SD/SDIO Card Interface
Copyright © 2009–2010, Texas Instruments Incorporated