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Enhanced Direct Memory Access (eDMA)
MPC5566 Microcontroller Reference Manual, Rev. 2
9-40
Freescale Semiconductor
4. Write the 32-byte TCD for each channel that can request service.
5. Enable any hardware service requests via the EDMA_ERQRH and/or EDMA_ERQRL registers.
6. Request channel service by either software (setting the TCD.START bit) or by hardware (slave
device asserting its eDMA peripheral request signal).
After any channel requests service, a channel is selected for execution based on the arbitration and priority
levels written into the programmer's model. The eDMA engine reads the entire TCD, including the
primary transfer control parameter shown in
, for the selected channel into its internal address
path module. As the TCD is being read, the first transfer is initiated on the system bus unless a
configuration error is detected. Transfers from the source (as defined by the source address, TCD.SADDR)
to the destination (as defined by the destination address, TCD.DADDR) continue until the specified
number of bytes (TCD.NBYTES) have been transferred. When the transfer is complete, the eDMA
engine's local TCD.SADDR, TCD.DADDR, and TCD.CITER are written back to the main TCD memory
and any minor loop channel linking is performed, if enabled. If the major loop is exhausted, further post
processing is executed: for example, interrupts, major loop channel linking, and scatter/gather operations,
if enabled.
shows how each DMA request initiates one minor loop transfer (iteration) without CPU
intervention. DMA arbitration can occur after each minor loop, and one level of minor loop DMA
preemption is allowed. The number of minor loops in a major loop is specified by the beginning iteration
count (biter).
Table 9-22. TCD Primary Control and Status Fields
TCD Field
Name
Description
START
Control bit to explicitly start channel when using a software
initiated DMA service (Automatically cleared by hardware)
ACTIVE
Status bit indicating the channel is currently in execution
DONE
Status bit indicating major loop completion (Cleared by software
when using a software initiated DMA service)
D_REQ
Control bit to disable DMA request at end of major loop
completion when using a hardware-initiated DMA service
BWC
Control bits for “throttling” bandwidth control of a channel
E_SG
Control bit to enable scatter-gather feature
INT_HALF
Control bit to enable interrupt when major loop is half complete
INT_MAJ
Control bit to enable interrupt when major loop completes
Содержание MPC5566
Страница 12: ...MPC5566 Microcontroller Reference Manual Devices Supported MPC5566 MPC5566 RM Rev 2 0 23 Apr 2008...
Страница 81: ...Introduction MPC5566 Microcontroller Reference Manual Rev 2 1 24 Freescale Semiconductor...
Страница 135: ...Signal Description MPC5566 Microcontroller Reference Manual Rev 2 2 54 Freescale Semiconductor...
Страница 189: ...Reset MPC5566 Microcontroller Reference Manual Rev 2 4 20 Freescale Semiconductor...
Страница 331: ...System Integration Unit SIU MPC5566 Microcontroller Reference Manual Rev 2 6 128 Freescale Semiconductor...
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Страница 455: ...Interrupt Controller INTC MPC5566 Microcontroller Reference Manual Rev 2 10 42 Freescale Semiconductor...
Страница 603: ...Flash Memory MPC5566 Microcontroller Reference Manual Rev 2 13 38 Freescale Semiconductor...
Страница 609: ...SRAM MPC5566 Microcontroller Reference Manual Rev 2 14 6 Freescale Semiconductor...
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Страница 997: ...Deserial Serial Peripheral Interface DSPI MPC5566 Microcontroller Reference Manual Rev 2 20 72 Freescale Semiconductor...
Страница 1037: ...Enhanced Serial Communication Interface eSCI MPC5566 Microcontroller Reference Manual Rev 2 21 40 Freescale Semiconductor...
Страница 1073: ...MPC5566 Microcontroller Reference Manual Rev 2 22 36 Freescale Semiconductor...
Страница 1081: ...Voltage Regulator Controller VRC and POR Module MPC5566 Microcontroller Reference Manual Rev 2 23 8 Freescale Semiconductor...
Страница 1093: ...IEEE 1149 1 Test Access Port Controller JTAGC MPC5566 Microcontroller Reference Manual Rev 2 24 12 Freescale Semiconductor...
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