SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
The single-packet mode asynchronous and control buffering scheme supports a maximum of one packet per buffer (that is, ping or pong). Both non-segmented and segmented data packets are allowed while using single-packet mode. Non-segmented packets are exchanged when only one buffer (that is ping or pong) is needed for packet transfer. Segmented packets are exchanged when a single packet is too long for one buffer and the packet must span multiple buffers. Figure 24-213 shows the memory space usage for both non-segmented and segmented asynchronous or control packets along with the packet start bit (PSn).
Figure 24-213 Single-Packet Mode Memory SpaceWhile using single-packet mode, buffer done (DNEn) is set in hardware when a packet is done or the buffer is full.
Table 24-1473 shows the format for single-packet mode asynchronous and control DMA descriptor table entries. For more details about the field descriptions see Table 24-1470.
| Bit Offset | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | CE | LE | PG | Reserved | ||||||||||||
| 16 | Reserved | |||||||||||||||
| 32 | RDY1 | DNE1 | ERR1 | PS1 | MEP1 | BD1[10:0] | ||||||||||
| 48 | RDY2 | DNE2 | ERR2 | PS2 | MEP2 | BD2[10:0] | ||||||||||
| 64 | BA1[15:0] | |||||||||||||||
| 80 | BA1[31:16] | |||||||||||||||
| 96 | BA2[15:0] | |||||||||||||||
| 112 | BA2[31:16] | |||||||||||||||