Enhanced Direct Memory Access Controller (eDMA)
21-58
Freescale Semiconductor
PXR40 Microcontroller Reference Manual, Rev. 1
the major loop. Two EDMA
_x
_TCD.ACTIVE bits set at the same time in the overall TCD map indicates
a higher priority channel is actively preempting a lower priority channel.
21.5.7
Channel Linking
Channel linking (or chaining) is a mechanism in which one channel sets the EDMA
_x
_TCD.START bit
of another channel (or itself), thus initiating a service request for that channel. This operation is
automatically performed by the eDMA engine at the conclusion of the major or minor loop when properly
enabled.
The minor loop channel linking occurs at the completion of the minor loop (or one iteration of the major
loop). The EDMA
_x
_TCD.CITER.E_LINK field are used to determine whether a minor loop link is
requested. When enabled, the channel link is made after each iteration of the minor loop except for the last.
When the major loop is exhausted, only the major loop channel link fields are used to determine if a
channel link should be made. For example, with the initial fields of:
EDMA
_x
_TCD.CITER.E_LINK = 1
EDMA
_x
_TCD.CITER.LINKCH = 0xC
EDMA
_x
_TCD.CITER value = 0x4
EDMA
_x
_TCD.MAJOR.E_LINK = 1
EDMA
_x
_TCD.MAJOR.LINKCH = 0x7
will execute as:
1. Minor loop done
set channel 12 EDMA
_x
_TCD.START bit
2. Minor loop done
set channel 12 EDMA
_x
_TCD.START bit
3. Minor loop done
set channel 12 EDMA
_x
_TCD.START bit
4. Minor loop done, major loop done
set channel 7 EDMA
_x
_TCD.START bit
When minor loop linking is enabled (EDMA
_x
_TCD.CITER.E_LINK = 1), the EDMA
_x
_TCD.CITER
field uses a nine bit vector to form the current iteration count.
When minor loop linking is disabled (EDMA
_x
_TCD.CITER.E_LINK = 0), the EDMA
_x
_TCD.CITER
field uses a 15-bit vector to form the current iteration count. The bits associated with the
EDMA
_x
_TCD.CITER.LINKCH field are concatenated onto the CITER value to increase the range of the
CITER.
NOTE
After configuration, the EDMA
_x
_TCD.CITER.E_LINK bit and the
EDMA
_x
_TCD.BITER.E_LINK bit must be equal or a configuration error
is reported. The CITER and BITER vector widths must be equal to calculate
the major loop, halfway done interrupt point.
summarizes how a DMA channel can link to another DMA channel, i.e, use another channel’s
TCD, at the end of a loop.
Содержание PXR4030
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Страница 120: ...Signal Descriptions 3 54 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 158: ...Power Management Controller PMC 5 26 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 182: ...Frequency Modulated Phase Locked Loop FMPLL 6 24 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 278: ...System Integration Unit SIU 7 96 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 280: ...System Information Module PXR40 Microcontroller Reference Manual Rev 1 8 2 Freescale Semiconductor...
Страница 300: ...Boot Assist Module BAM 9 20 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 346: ...Interrupts and Interrupt Controller INTC 10 46 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 352: ...General Purpose Static RAM SRAM 11 6 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 432: ...Core e200z7 Overview PXR40 Microcontroller Reference Manual Rev 1 13 44 Freescale Semiconductor...
Страница 460: ...Peripheral Bridge PBRIDGE 15 16 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 478: ...Memory Protection Unit MPU 16 18 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 496: ...Error Correction Status Module ECSM 17 18 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 524: ...Periodic Interrupt Timer PIT_RTI 20 12 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 740: ...FlexRay Communication Controller FLEXRAY 22 156 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 860: ...FlexCAN Module 24 50 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 928: ...Deserial Serial Peripheral Interface DSPI 25 68 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 982: ...Enhanced Serial Communication Interface eSCI 26 54 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 1114: ...Enhanced Queued Analog to Digital Converter EQADC 27 132 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 1167: ...Decimation Filter Freescale Semiconductor 28 53 PXR40 Microcontroller Reference Manual Rev 1...
Страница 1168: ...Decimation Filter 28 54 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 1262: ...Enhanced Time Processing Unit eTPU2 29 94 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Страница 1399: ...Nexus Development Interface NDI Freescale Semiconductor 31 83 PXR40 Microcontroller Reference Manual Rev 1...
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