SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
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 26-235 shows the memory space usage for both non-segmented and segmented asynchronous or control packets along with the packet start bit (PSn).
While using single-packet mode, buffer done (DNEn) is set in hardware when a packet is done or the buffer is full.
Table 26-1639 shows the format for single-packet mode asynchronous and control DMA descriptor table entries. For more details about the field descriptions see Table 26-1636.
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] |