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Enhanced Direct Memory Access Controller (eDMA)
PXN20 Microcontroller Reference Manual, Rev. 1
24-46
Freescale Semiconductor
The following coherency model is recommended when executing a dynamic channel link or dynamic
scatter-gather request:
1. Set the TCD.MAJOR.E_LINK bit.
2. Read back the TCD.MAJOR.E_LINK bit
3. Test the TCD.MAJOR.E_LINK request status:
a) If the bit is set, the dynamic link attempt was successful.
b) If the bit is cleared, the attempted dynamic link did not succeed, the channel was already
retiring.
This same coherency model is true for dynamic scatter-gather operations. For both dynamic requests, the
TCD local memory controller forces the TCD.MAJOR.E_LINK and TCD.E_SG bits to zero on any writes
to a channel’s TCD after that channel’s TCD.DONE bit is set indicating the major loop is complete.
NOTE
The user must clear the TCD.DONE bit before writing the
TCD.MAJOR.E_LINK or TCD.E_SG bits. The TCD.DONE bit is cleared
automatically by the eDMA engine after a channel begins execution.
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...