
Enhanced Direct Memory Access (eDMA)
16-38
Freescale Semiconductor
from the TCD local memory at the end of channel execution, therefore allowing software to enable either
feature during channel execution.
Because software can change the configuration during execution, a coherency sequence must be followed.
Consider the scenario the user attempts to execute a dynamic channel link by enabling the
TCD
n
_CSR[MAJOR_E_LINK] bit as the eDMA engine retires the channel. The
TCD
n
_CSR[MAJOR_E_LINK] would be set in the programmer’s model, but it would be indeterminate
whether the actual link was made before the channel retired.
The following coherency sequence is recommended when executing a dynamic channel link or dynamic
scatter/gather request:
1. Set the TCD
n
_CSR[MAJOR_E_LINK] bit.
2. Read back the TCD
n
_CSR[MAJOR_E_LINK] bit.
3. Test the TCD
n
_CSR[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
n
_CSR[MAJOR_E_LINK] and TCD
n
_CSR[E_SG] bits to
zero on any writes to a TCD
n
after the TCD
n
_CSR[DONE] bit for that channel is set, indicating the major
loop is complete.
NOTE
Software must clear the TCD
n
_CSR[DONE] bit before writing the
TCD
n
_CSR[MAJOR_E_LINK] or TCD
n
_CSR[E_SG] bits. The
TCD
n
_CSR[DONE] bit is cleared automatically by the eDMA engine after
a channel begins execution.
MCF5329 Reference Manual, Rev 3
Содержание MCF5329
Страница 106: ...ColdFire Core 3 32 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 126: ...Enhanced Multiply Accumulate Unit EMAC 4 20 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 148: ...Cache 5 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 154: ...Static RAM SRAM 6 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 184: ...Power Management 8 18 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 204: ...Reset Controller Module 10 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 220: ...System Control Module SCM 11 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 228: ...Crossbar Switch XBS 12 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 268: ...General Purpose I O Module 13 40 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 392: ...SDRAM Controller SDRAMC 18 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 436: ...Fast Ethernet Controller FEC 19 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 564: ...Liquid Crystal Display Controller LCDC 22 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 594: ...FlexCAN 23 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 678: ...Pulse Width Modulation PWM Module 26 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 684: ...Watchdog Timer Module 27 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 692: ...Programmable Interrupt Timers PIT0 PIT3 28 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 704: ...DMA Timers DTIM0 DTIM3 29 12 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 720: ...Queued Serial Peripheral Interface QSPI 30 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 754: ...UART Modules 31 34 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 770: ...I2 C Interface 32 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 790: ...Message Digest Hardware Accelerator MDHA 33 20 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 866: ...Debug Module 36 50 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 902: ...Register Memory Map Quick Reference A 26 Freescale Semiconductor MCF5329 Reference Manual Rev 3...