15-17
MB86R02 ‘Jade-D’ Hardware Manual V1.64
Restrictions
When DMA transfer is performed by an external (DREQ) or peripheral (IDREQ) request, there
are restrictions for external and peripheral signal pins.
1.
DREQ/IDREQ
DREQ/IDREQ must be asserted for at least 2 cycles of the AHB clock
(
HCLK).
There is no restriction for the timing of negating DREQ/IDREQ.
After asserting DACK/IDACK, DMAC is able to accept new a transfer request (edge of
DREQ/IDREQ) for the next DMA transfer.
2.
DACK/IDACK
After the DMAC transfers data to the destination address, DACK/IDACK are asserted for 1
cycle of the AHB clock (HCLK). If access to the destination is executed correctly, this signal
is asserted. If destination issues, error, retry or split responses occur on the AHB, it is not
asserted.
In block transfer mode, these signals indicate that the DMAC has correctly performed
destination access.
3.
DEOP (Data End Operation)/IDEOP
Basically, DEOP/IDEOP is asserted for 1 AHB clock (HCLK) cycle if the DMAC terminates
DMA transfer properly or abnormally. Abnormal DMA transfer includes the following cases:
•
Forced termination by DSTP/IDSTP
•
Forced termination by setting 1'b0 to DMACA/EB
•
Reception of an error response from the source/destination
4.
DSTP (Data Stop)/IDSTP
DSTP/IDSTP are used to forcibly terminate DMA transfer and asserting them during the
transfer is permitted (it is also permissible to assert DSTP/IDSTP while DMA data is not
transferred due to a transfer gap or an interrupt function).
If these signals are used to forcibly terminate DMA transfer, they are not asserted until
DEOP/IDEOP are asserted.
5.
Exceptional operation of DEOP/IDEOP
If DSTP/IDSTP are asserted immediately after asserting DREQ/DSTP, the DMAC may
request the bus to execute an IDLE transfer. In this case, the DMAC may assert
DEOP/IDEOP for 2 or more cycles of the AHB clock (HCLK).
The assertion period of DEOP/IDEOP depends on the number of previous master transfer
cycles. Figure 15-2 shows an example of this exception operation.
Summary of Contents for MB86R02
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Page 76: ...3 2 MB86R02 Jade D Hardware Manual V1 64 Figure 3 1 Memory map 1 ...
Page 77: ...3 3 MB86R02 Jade D Hardware Manual V1 64 Figure 3 2 Memory map 2 ...
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Page 214: ...11 7 MB86R02 Jade D Hardware Manual V1 64 15 16 cycles initial value ...
Page 497: ...18 139 MB86R02 Jade D Hardware Manual V1 64 VSYNC is output 1 dot clock faster than HSYNC ...
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Page 682: ...22 2 MB86R02 Jade D Hardware Manual V1 00 FUJITSU PROPRIETARY AND CONFIDENTIAL ...
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