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CHAPTER 17 DMA CONTROLLER
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Continuous transfer mode
1. Use an initialization routine to set the descriptor.
2. Use the appropriate program to initialize the DMA transfer request source. Set the external
transfer request input pin to H or L level detection.
3. Use the program to set the DOEn bit in the desired DACSR to 1. This completes the DMA
setup.
4. When the DMAC detects DMA transfer request input, its requests the CPU to acquire the
bus right.
5. When the CPU assigns the bus right, the DMAC accesses three-word information in the
descriptor via the bus.
6. DMACT subtraction is performed, and data is transferred once in accordance with the
information in the descriptor. During data transfer, the transfer-request-acceptance output
signal is output. When the DMACT subject to the subtraction becomes 0, the transfer-end
output signal is output during data transfer.
7. If the DMACT value is not 0 and a peripheral DMA request still exists, step 6) is repeated.
(Step 8) is used depending on the bus status.)
8. If the DMACT value is 0 or if a peripheral DMA request is cleared, SADR or DADR addition
or subtraction is performed, and a new value is written back to the descriptor together with
the DMACT value.
9. The bus right is returned to the CPU.
10.If the counter value is 0, DACSR DEDn is set to 1, and a CPU interrupt is generated if
interrupts are enabled.
If the descriptor is stored in the internal RAM, and data of byte length is transferred between
external buses, the required minimum cycle count per transfer is as described below, under the
conditions indicated:
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When both the transfer source and destination addresses are fixed: (6 + 5 x n) cycles
•
When only one of the transfer source and destination addresses is fixed: (7 + 5 x n) cycles
•
When both the transfer source and destination addresses are incremented or decremented:
(8 + 5 x n) cycles
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Burst transfer mode
1. Use an initialization routine to set the descriptor.
2. Use the appropriate program to initialize the DMA transfer request source. If the internal
peripheral circuit is the transfer request source, enable interrupt requests. At the same time,
disable interrupt controller ICR.
3. Use the program to set the DOEn bit in the desired DACSR to 1. This completes the DMA
setup.
4. When the DMAC detects DMA transfer request input, it requests the CPU to acquire the bus
right.
5. When the CPU assigns the bus right, the DMAC accesses three-word information in the
descriptor via the bus.
6. Data is transferred in accordance with the descriptor information by the number of times set
in the DMACT during DMACT subtraction. The transfer-request-acceptance output signal is
output during data transfer. (If external transfer request input is used,) the transfer-end
output signal is output during data transfer when the DMACT becomes 0.
7. SADR or DADR addition or subtraction is performed, and a new value is written back to the
Содержание MB91150 Series
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Страница 3: ...FUJITSU LIMITED FR30 32 BIT MICROCONTROLLER MB91150 Series HARDWARE MANUAL ...
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Страница 112: ...96 CHAPTER 3 MEMORY SPACE CPU AND CONTROL UNIT ...
Страница 174: ...158 CHAPTER 5 I O PORTS Note DDRI bit 6 is a test bit Always set the bit to 0 The value read from this bit is always 0 ...
Страница 178: ...162 CHAPTER 5 I O PORTS ...
Страница 214: ...198 CHAPTER 7 16 BIT RELOAD TIMER ...
Страница 240: ...224 CHAPTER 8 PPG TIMER ...
Страница 310: ...294 CHAPTER 13 8 10 BIT A D CONVERTER ...
Страница 318: ...302 CHAPTER 14 8 BIT D A CONVERTER ...
Страница 362: ...346 CHAPTER 15 UART ...
Страница 420: ...404 CHAPTER 19 PERIPHERAL STOP CONTROL ...
Страница 428: ...412 CHAPTER 20 CALENDAR MACROS ...
Страница 503: ...487 INDEX INDEX The index follows on the next page This is listed in alphabetic order ...
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