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Enhanced Direct Memory Access Controller (eDMA)
PXN20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor
24-35
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 DMA 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 24-21. 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 PXN2020
Page 1: ...PXN20 Microcontroller Reference Manual Devices Supported PXN2020 PXN2120 PXN20RM Rev 1 06 2011...
Page 42: ...PXN20 Microcontroller Reference Manual Rev 1 lxiv Freescale Semiconductor...
Page 64: ...Introduction PXN20 Microcontroller Reference Manual Rev 1 1 22 Freescale Semiconductor...
Page 112: ...Signal Description PXN20 Microcontroller Reference Manual Rev 1 3 44 Freescale Semiconductor...
Page 118: ...Resets PXN20 Microcontroller Reference Manual Rev 1 4 6 Freescale Semiconductor...
Page 372: ...e200z6 Core Z6 PXN20 Microcontroller Reference Manual Rev 1 13 8 Freescale Semiconductor...
Page 412: ...e200z0 Core Z0 PXN20 Microcontroller Reference Manual Rev 1 14 14 Freescale Semiconductor...
Page 821: ...Media Local Bus MLB PXN20 Microcontroller Reference Manual Rev 1 Freescale Semiconductor 27 49...
Page 822: ...Media Local Bus MLB PXN20 Microcontroller Reference Manual Rev 1 27 50 Freescale Semiconductor...
Page 1376: ...Memory Map PXN20 Microcontroller Reference Manual Rev 1 A 118 Freescale Semiconductor...