472
/
838
Nations Technologies Inc.
Tel
：
+86-755-86309900
：
Address: Nations Tower, #109 Baoshen Road, Hi-tech Park North.
Nanshan District, Shenzhen, 518057, P.R.China
ERASE_TIMEOUT
Value definition
02
2 sec
03
3 sec
……
……
63
63 sec
ERASE_OFFSET
These 2 bits give TOFFSET, which can select one of the four values shown in the table below. When ERASE_SIZE
and ERASE_TIMEOUT are both 0, this value has no meaning.
Table 18-15 Erase Offset Codes
ERASE_OFFSET
Value definition
0
0 sec
1
1 sec
2
2 sec
3
3 sec
18.4.12
SD I/O mode
I/O interrupts
There is a pin (pin 8) with interrupt function on the SD interface, which enables the SD I/O card to interrupt the
multi-media card/SD module. In 4-bit SD mode, this pin is SDIO_DAT1, through which the card sends the multi-
media card to the multi-media card. The /SD module makes an interrupt request. For each card or function within the
card, the interrupt function is optional.
The interrupt of SD I/O is level-effective, that is, the interrupt signal line must maintain the active level (low) before
it can be recognized and responded by the multimedia card/SD module, and remains inactive level (high) after the
interrupt process ends. After the interrupt request has been serviced by the MultiMediaCard/SD module, the interrupt
status bits can be cleared by writing the appropriate bits to the SD I/O card's internal registers through an I/O write
operation.
The interrupt outputs of the SD I/O card are all active low, and the multimedia card/SD module provides pull-up
resistors on all data lines (SDIO/D[3:0]). The multimedia card/SD module samples the 8th pin (SDIO_DAT/IRQ)
and performs interrupt detection only in the interrupt stage, and ignores the value on the signal line at other times.
Both I/O operations and memory operations have interrupt stages, and the definition of the interrupt stage for single
data block operations and multiple data block transfer operations is different.
I/O suspend and resume
In a multifunction SD I/O card, or in a card with both I/O and memory functions, multiple devices (I/O and memory)
share the MMC/SD bus. In order to enable multiple devices to share the bus in the MMC/SD module, SD I/O cards
and composite cards can selectively implement the concept of suspend/resume; in cards that support suspend/resume,
the MMC/SD module can suspend a A data transfer operation of a function or memory to give up the bus to another
function or memory with a higher priority, and resume the previously suspended transfer after the transfer of the
function or memory with a higher priority is completed.
