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MOTOROLA
Chapter 16. DMA Controller Module
16-15
DMA Controller Module Functional Description
16.5.4.2 Bandwidth Control
Bandwidth control makes it possible to force the DMA off the bus to allow access to
another device. DCR
n
[BWC] provides seven levels of block transfer sizes. If the BCR
n
decrements to a multiple of the decode of the BWC, the DMA bus request negates until the
bus cycle terminates. If a request is pending, the arbiter may then pass bus mastership to
another device. If auto-alignment is enabled, DCR
n
[AA] = 1, the BCR
n
may skip over the
programmed boundary, in which case, the DMA bus request is not negated.
If BWC = 000, the request signal remains asserted until BCR
n
reaches zero. DMA has
priority over the core. Note that in this scheme, the arbiter can always force the DMA to
relinquish the bus. See Section 8.5.3, “Bus Master Park Register (MPARK).”
16.5.5 Termination
An unsuccessful transfer can terminate for one of the following reasons:
• Error conditions—When the MCF5282 encounters a read or write cycle that
terminates with an error condition, DSR
n
[BES] is set for a read and DSR
n
[BED] is
set for a write before the transfer is halted. If the error occurred in a write cycle, data
in the internal holding register is lost.
• Interrupts—If DCR
n
[INT] is set, the DMA drives the appropriate internal interrupt
signal. The processor can read DSR
n
to determine whether the transfer terminated
successfully or with an error. DSR
n
[DONE] is then written with a one to clear the
interrupt and the DONE and error bits.
Содержание ColdFire MCF5281
Страница 1: ...MCF5282UM D Rev 2 1 2004 MCF5282 ColdFire Microcontroller User s Manual Devices Supported MCF5281 ...
Страница 124: ...3 20 MCF5282 User s Manual MOTOROLA EMAC Instruction Set Summary ...
Страница 141: ...MOTOROLA Chapter 5 Static RAM SRAM 5 5 SRAM Programming Model ...
Страница 142: ...5 6 MCF5282 User s Manual MOTOROLA SRAM Programming Model ...
Страница 168: ...6 26 MCF5282 User s Manual MOTOROLA Interrupts ...
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Страница 246: ...10 18 MCF5282 User s Manual MOTOROLA Low Power Wakeup Operation ...
Страница 254: ...11 8 MCF5282 User s Manual MOTOROLA Memory Map and Registers ...
Страница 264: ...12 10 MCF5282 User s Manual MOTOROLA Chip Select Registers ...
Страница 280: ...13 16 MCF5282 User s Manual MOTOROLA Misaligned Operands ...
Страница 314: ...14 34 MCF5282 User s Manual MOTOROLA MCF5282 External Signals ...
Страница 339: ...MOTOROLA Chapter 15 Synchronous DRAM Controller Module 15 25 SDRAM Example ...
Страница 340: ...15 26 MCF5282 User s Manual MOTOROLA SDRAM Example ...
Страница 356: ...16 16 MCF5282 User s Manual MOTOROLA DMA Controller Module Functional Description ...
Страница 408: ...17 52 MCF5282 User s Manual MOTOROLA Buffer Descriptors ...
Страница 446: ...20 24 MCF5282 User s Manual MOTOROLA Interrupts ...
Страница 474: ...22 18 MCF5282 User s Manual MOTOROLA Programming Model ...
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Страница 526: ...24 16 MCF5282 User s Manual MOTOROLA I2C Programming Examples ...
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Страница 718: ...29 46 MCF5282 User s Manual MOTOROLA Motorola Recommended BDM Pinout ...
Страница 750: ...32 8 MCF5282 User s Manual MOTOROLA Ordering Information ...
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