207
CK
DREQ
DACK
Bus cycle
CPU
CPU
CPU
DMAC (R) DMAC (W)
CPU
CPU
CPU
DMAC (R): DMAC read cycle
DMAC (W): DMAC write cycle
Note:
Illustrates the case when DACK is output during the DMAC write cycle.
Figure 9.16
DREQ
Sampling Timing in Cycle-Steal Mode (Output with
DREQ
Level
Detection and DACK Active-Low) (Dual Address Mode, Bus Cycle = 2 States)
CK
DREQ
DACK
Bus cycle
T2
Tw
T1
DMAC
T2
Tw
T1
CPU
CPU
CPU
DMAC
CPU
CPU
Note:
When
DREQ
is negated at the third state of the DMAC cycle, the next DMA transfer will
be executed because the sampling is performed at the second state of the DMAC cycle.
Figure 9.17
DREQ
Sampling Timing in Cycle-Steal Mode (Output with
DREQ
Level
Detection and DACK Active-Low) (Single Address Mode, Bus Cycle = 2 1 Wait
State)
Summary of Contents for HD6417032
Page 21: ......
Page 35: ...xiv ...
Page 85: ...50 ...
Page 101: ...66 ...
Page 129: ...94 ...
Page 135: ...100 ...
Page 343: ...308 ...
Page 369: ...334 ...
Page 383: ...348 ...
Page 475: ...440 ...
Page 525: ...490 CK RAS CAS TRp TRc TRcc tRASD1 tRASD2 tCASD3 tCASD2 TRr tCSR Figure 20 18 Self Refresh ...
Page 578: ...543 CK RAS CAS TRp TRc TRcc tRASD1 tRASD2 tCASD3 tCASD2 TRr tCSR Figure 20 62 Self Refresh ...
Page 689: ...654 ...