Rev. 3.0, 04/02, page 522 of 1064
14.5.2
Pins in DDT Mode
Figure 14.24 shows the system configuration in DDT mode.
Synchronous
DRAM
/
/DRAK0
/
/DACK0
ID1, ID0/DRAK1, DACK1
CLK
D31–D0 = DTR
External device
SH7751 Series
A25–A0, RAS, CAS, WE, DQMn, CKE
Figure 14.24 System Configuration in On-Demand Data Transfer Mode
: Data bus release request signal for transmitting the data transfer request format (DTR
format) or a DMA request from an external device to the DMAC
If there is a wait for release of the data bus, an external device can have the data bus released
by asserting
. When is accepted, the BSC asserts .
: Data bus D31–D0 release signal
Assertion of
means that the data bus will be released two cycles later.
: Transfer request signal
Assertion of
has the following different meanings.
In normal data transfer mode (except channel 0),
is asserted, and at the same time the
DTR format is output, two cycles after
is asserted.
In the case of the handshake protocol without use of the data bus, asserting
enables a
transfer request to be issued for the channel for which a transfer request was made
immediately before. This function can be used only when
is not asserted two cycles
earlier.
In the case of direct data transfer mode (valid only for channel 2), a direct transfer request
can be made to channel 2 by asserting
and simultaneously.
Summary of Contents for SH7751
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