
Enhanced Direct Memory Access (eDMA)
Freescale Semiconductor
16-3
16.4.2
Debug Mode
In debug mode, the eDMA stops transferring data. If debug mode is entered during the transfer of a data
block described by a minor loop in the current active channel’s TCD, the eDMA continues operation until
completion of the minor loop.
16.5
External Signal Description
This section describes the external signals of the eDMA controller.
16.5.1
External Signal Timing
Asserting the external DMA request signal, DREQ
n
, initiates a service request for that channel. It must
remain asserted until the corresponding DACK
n
signal indicates the channel’s data transfer has started.
The DACK
n
output is asserted for one cycle during the address phase of the channel’s first internal read
access.
•
When no further requests are needed, the DREQ
n
signal must negate after the DACK
n
assertion
and on or before the second cycle following the data phase of the last internal bus write (see
).
•
If another service request is needed, DREQ
n
may simply remain asserted.
•
To request continuous service, DREQ
n
may remain continuously asserted.
Figure 16-2. DREQn and DACKn Timing
After a service request has been initiated, it cannot be canceled. Removing a service request after it has
been asserted may result in one of three actions depending on the DMA engine’s status:
•
The request is never recognized because another channel is executing.
Table 16-1. External Signal List
Signal Name
I/O
Description
DREQ0
DREQ1
I
Provides external requests from peripherals needing DMA service. When
asserted, the device is requesting service. This request pin is tied to DMA
channel 0 and 1, respectively.
DACK0
DACK1
O
Indicates when the external DMA request has been acknowledged.
Internal
Internal
DACKn
DREQn
Internal
wr1
rd1
rd2
wr2
wr1
rd1
rd2
wr2
Address Phase
Data Phase
Bus Clock
MCF5329 Reference Manual, Rev 3
Содержание MCF5329
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Страница 126: ...Enhanced Multiply Accumulate Unit EMAC 4 20 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
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Страница 184: ...Power Management 8 18 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 204: ...Reset Controller Module 10 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 220: ...System Control Module SCM 11 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 228: ...Crossbar Switch XBS 12 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
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Страница 436: ...Fast Ethernet Controller FEC 19 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 564: ...Liquid Crystal Display Controller LCDC 22 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 594: ...FlexCAN 23 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 678: ...Pulse Width Modulation PWM Module 26 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 684: ...Watchdog Timer Module 27 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 692: ...Programmable Interrupt Timers PIT0 PIT3 28 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 704: ...DMA Timers DTIM0 DTIM3 29 12 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 720: ...Queued Serial Peripheral Interface QSPI 30 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
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Страница 790: ...Message Digest Hardware Accelerator MDHA 33 20 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 866: ...Debug Module 36 50 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
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