Transmit_Poll_Demand
The Transmit Poll Demand register enables the Tx DMA to check whether or not the DMA owns the current descriptor. The Transmit Poll Demand command is given to wake up the Tx DMA if it is in the Suspend mode. The Tx DMA can go into the Suspend mode because of an Underflow error in a transmitted frame or the unavailability of descriptors owned by it. You can give this command anytime and the Tx DMA resets this command when it again starts fetching the current descriptor from host memory.
| Module Instance | Base Address | Register Address |
|---|---|---|
| emac0 | 0xFF700000 | 0xFF701004 |
| emac1 | 0xFF702000 | 0xFF703004 |
Offset: 0x1004
Access: RW
| Bit Fields | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 |
tpd RW 0x0 |
|||||||||||||||
| 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
tpd RW 0x0 |
|||||||||||||||
Transmit_Poll_Demand Fields
| Bit | Name | Description | Access | Reset |
|---|---|---|---|---|
| 31:0 | tpd | When these bits are written with any value, the DMA reads the current descriptor pointed to by Register 18 (Current Host Transmit Descriptor Register). If that descriptor is not available (owned by the Host), the transmission returns to the Suspend state and the Bit 2 (TU) of Register 5 (Status Register) is asserted. If the descriptor is available, the transmission resumes. |
RW | 0x0 |