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.
Summary of Contents for Blackfin ADSP-BF537
Page 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Page 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 876: ...Programming Examples 14 36 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 938: ...Programming Examples 15 62 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...