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CHAPTER 17 DMA CONTROLLER
17.4.4 Differences Because of DREQ Sense Mode
The DREQ sense modes include level and edge modes. This section provides notes on
each mode.
■
Notes on level mode
In level sense mode, be careful that no overrun occurs during DMAC transfer.
Negate DREQ until the rising DACK edge during transfer destination access.
Figure 17.4-5 "Level-mode timing" shows the level-mode timing.
Figure 17.4-5 Level-mode timing
CLK
DREQ
DACK
Internal
D-A
external
A bus
Descriptor reading
Transfer
destination
Transfer
destination
Source reading
Writing to destination
Descriptor writing
A
B
DREQ
DREQ(NG)
Transfer is performed twice
per transfer request.
Up to 1 cycle
A:
Request flag clearance point
Sensing start point for the next DREQ in edge sense mode
Sensing start point for the next DREQ in continuous transfer mode
B:
Sensing start point for the next DREQ during single and block transfer in level sense mode
Note: The timing from DREQ to DMA start reflects the case where this is performed close to top speed.
Summary of Contents for MB91150 Series
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Page 3: ...FUJITSU LIMITED FR30 32 BIT MICROCONTROLLER MB91150 Series HARDWARE MANUAL ...
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Page 10: ...vi ...
Page 112: ...96 CHAPTER 3 MEMORY SPACE CPU AND CONTROL UNIT ...
Page 178: ...162 CHAPTER 5 I O PORTS ...
Page 214: ...198 CHAPTER 7 16 BIT RELOAD TIMER ...
Page 240: ...224 CHAPTER 8 PPG TIMER ...
Page 310: ...294 CHAPTER 13 8 10 BIT A D CONVERTER ...
Page 318: ...302 CHAPTER 14 8 BIT D A CONVERTER ...
Page 362: ...346 CHAPTER 15 UART ...
Page 420: ...404 CHAPTER 19 PERIPHERAL STOP CONTROL ...
Page 428: ...412 CHAPTER 20 CALENDAR MACROS ...
Page 503: ...487 INDEX INDEX The index follows on the next page This is listed in alphabetic order ...
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