DMA
SC32442B RISC MICROPROCESSOR
8-4
Demand/Handshake Mode Comparison
Demand and Handshake modes are related to the protocol between XnXDREQ and XnXDACK. Figure 8-2 shows
the differences between the two modes.
At the end of one transfer (Single/Burst transfer), DMA checks the state of double-synched XnXDREQ.
Demand mode
-
If XnXDREQ remains asserted, the next transfer starts immediately. Otherwise it waits for XnXDREQ to
be asserted.
Handshake mode
-
If XnXDREQ is de-asserted, DMA de-asserts XnXDACK in 2cycles. Otherwise it waits until XnXDREQ is
de-asserted.
Caution: XnXDREQ has to be asserted (low) only after the de-assertion (high) of XnXDACK.
Demand Mode
XSCLK
XnXDACK
XnXDACK
XnXDREQ
XnXDREQ
2cycles
Double
synch
Read
Write
Read
Write
Handshake Mode
BUS Acquisiton
Actual
Transfer
1st Transfer
2nd Transfer
2cycles
Read
Write
Double
synch
2cycles
Figure 8-2. Demand/Handshake Mode Comparison
Содержание SC32442B54
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Страница 59: ...PROGRAMMER S MODEL SC32442B RISC MICROPROCESSOR 2 16 NOTES ...
Страница 123: ...ARM INSTRUCTION SET SC32442B RISC MICROPROCESSOR 3 64 NOTES ...
Страница 167: ...THUMB INSTRUCTION SET SC32442B RISC MICROPROCESSOR 4 44 NOTES ...
Страница 187: ...MEMORY CONTROLLER SC32442B RISC MICROPROCESSOR 5 20 NOTES ...
Страница 250: ...DMA SC32442B RISC MICROPROCESSOR 8 14 NOTES ...
Страница 308: ...PWM TIMER SC32442B RISC MICROPROCESSOR 10 20 NOTES ...
Страница 330: ...UART SC32442B RISC MICROPROCESSOR 11 22 NOTES ...
Страница 417: ...SC32442B RISC MICROPROCESSOR LCD CONTROLLER 15 45 NOTES ...
Страница 427: ...ADC AND TOUCH SCREEN INTERFACE SC32442B RISC MICROPROCESSOR 16 10 NOTES ...
Страница 511: ...BUS PRIORITIES SC32442B RISC MICROPROCESSOR 24 2 NOTES ...
Страница 562: ...K5D2G13ACM D075 Revision 1 0 December 2006 7 MCP MEMORY 2Gb 256Mb x8 NAND Flash Memory A Die ...
Страница 599: ...K5D2G13ACM D075 Revision 1 0 December 2006 44 MCP MEMORY 512Mb 16Mb x32 Mobile SDRAM C Die ...