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Description of Operation
8-30
ADSP-BF537 Blackfin Processor Hardware Reference
TX DMA Direction Errors
The TX DMA channel halts immediately after any transfer that sets the
TXDMAERR
bit in the
EMAC_SYSTAT
register. This bit is set if a TX data or sta-
tus DMA request is granted by the DMA channel, but the DMA channel
is programmed to transfer in the wrong direction. Data DMA should be
memory-read; status DMA should be memory-write. TX DMA errors
could indicate a software problem in managing the TX DMA descriptor
queue.
In order to facilitate software debugging, the TX DMA channel guaran-
tees that the last transfer to occur is the one with the direction error. On
an error, usually the current frame is corrupted. Any later frames in the
descriptor queue are not sent until the error is cleared. Since the MAC
may have lost synchronization with the DMA descriptor queue, the TX
channel must be disabled in order to clear the error condition.
To clear the error and resume operation, perform these steps:
1. Disable the MAC TX channel (clear the
TE
bit in the
EMAC_OPCODE
register).
2. Disable the DMA channel.
3. Clear the
TXDMAERR
bit in the
EMAC_SYSSTAT
register by writing 1 to
it.
4. Reconfigure the MAC and the DMA engine as if starting from
scratch.
5. Re-enable the DMA channel.
6. Re-enable the MAC TX channel.
Содержание Blackfin ADSP-BF537
Страница 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 876: ...Programming Examples 14 36 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 938: ...Programming Examples 15 62 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...