SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
The channel allocation table comprises 16 entries of the channel table RAM. Each entry is 16-bit. The first entry starts at address 0x80 and the sixteenth entry at address 0x8F. Each 16-bit channel allocation table entry represents a logical connection to or from a transmit/receive device (that is, MediaLB or DMA channel). All entries are indexed according to a fixed physical address assigned to every Rx/Tx channel. This is shown in Table 26-1627. The value stored in a channel allocation table entry includes a 6-bit connection label (CL[5:0]), which provides a pointer to the channel descriptor table. To complete a logical channel and form a routing connection, system software must assign the same connection label to both the Rx and Tx channels.
| Peripheral | Number of Tx Channels Allowed | Number of Rx Channels Allowed | Channel Allocation Table Start Index | Channel Allocation Table End Index | Entries |
|---|---|---|---|---|---|
| MediaLB | 0 to 64 | 64 - (Number of Tx channels) | 0 | 63 | 64 |
| DMA | 0 to 64 | 64 - (Number of Tx channels) | 64 | 127 | 64 |
The format of a full channel allocation table entry is shown in Table 26-1628. All reserved bits should be written to zero.
| Channel Type | 15 | 14 | 13 | 12 | 11 | 10 | 8 | 7 | 6 | 5 | 0 | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Isochronous | Reserved | FCE | Reserved | RNW | CE | CT[2:0] = 3 | Reserved | CL[5:0] | ||||||||
| Asynchronous | Reserved | MT | RNW | CE | CT[2:0] = 2 | Reserved | CL[5:0] | |||||||||
| Control | Reserved | MT | RNW | CE | CT[2:0] = 1 | Reserved | CL[5:0] | |||||||||
| Synchronous | Reserved | MFE | MT | RNW | CE | CT[2:0] = 0 | Reserved | CL[5:0] | ||||||||
The field descriptions of a channel allocation table entry are shown in Table 26-1629.
| Field | Description |
|---|---|
| CL[5:0] | Connection Label (offset into channel descriptor table) |
| CT[2:0] | Channel type |
| 111 = Reserved | |
| 110 = Reserved | |
| 101 = Reserved | |
| 100 = Reserved | |
| 011 = Isochronous | |
| 010 = Asynchronous | |
| 001 = Control | |
| 000 = Synchronous | |
| CE | Channel enable |
| 0 = Disabled | |
| 1= Enabled | |
| RNW | Read, not Write (1) |
| 1 = Read | |
| 0 = Write | |
| MT | Mute Bit (2) |
| 1= Enabled | |
| 0 = Disabled | |
| FCE | Flow control enable (3) |
| 1 = Enabled | |
| 0 = Disabled | |
| MFE | Multi-frame per sub-buffer enable (4) |
| 1 = Enabled | |
| 0 = Disabled | |
| Reserved | Reserved. Software writes zeros to all reserved bits when the entry is initialized. The reserved bits are read-only after initialization. |