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Enhanced Direct Memory Access Controller (eDMA)
MPC5644A Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor
177
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, EDMA_TCD[SADDR]) to
the destination (as defined by the destination address, EDMA_TCD.DADDR) continue until the specified
number of bytes (EDMA_TCD[NBYTES]) have been transferred. When the transfer is complete, the
DMA engine's local EDMA_TCD[SADDR], EDMA_TCD.DADDR, and EDMA_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
pre-emption is allowed. The number of minor loops in a major loop is specified by the beginning iteration
count (biter).
Table 8-21. TCD primary control and status fields
TCD field name
Description
START
Control bit to 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
Summary of Contents for MPC5644A
Page 2: ...MPC5644A Microcontroller Reference Manual Rev 6 2 Freescale Semiconductor...
Page 24: ...MPC5644A Microcontroller Reference Manual Rev 6 24 Freescale Semiconductor...
Page 26: ...MPC5644A Microcontroller Reference Manual Rev 6 26 Freescale Semiconductor...
Page 52: ...Introduction MPC5644A Microcontroller Reference Manual Rev 6 52 Freescale Semiconductor...
Page 56: ...Memory Map MPC5644A Microcontroller Reference Manual Rev 6 56 Freescale Semiconductor...
Page 1228: ...Decimation Filter MPC5644A Microcontroller Reference Manual Rev 6 1228 Freescale Semiconductor...
Page 1440: ...FlexCAN Module MPC5644A Microcontroller Reference Manual Rev 6 1440 Freescale Semiconductor...