A MediaLB logical channel is defined as all physical channels associated with a single ChannelAddress. A logical channel on MediaLB is unidirectional; therefore, a single MediaLB Device sends data on a logical channel to one or more receiving Devices. If two Devices require bidirectional communication, then two MediaLB logical channels are required.
A ChannelAddress is 16-bits wide. Of the 16-bits, ChannelAddress (CA) bits 15 through 9 and the LSB are always zero. Only the eight bits CA[8:1] vary. A delay of one physical channel exists between the occurrence of the ChannelAddress and the actual physical channel granted. The 0x01FE ChannelAddress is defined as the FRAMESYNC pattern, where the end of the pattern determines the byte boundary, the physical channel boundary, and indicates that the MediaLB frame starts one physical channel later (PC0). The 0x0000 ChannelAddress is defined as the BusIdle state, which indicates that the corresponding physical channel is not assigned and not used by any Device. All odd ChannelAddresses are reserved; therefore, the LSB of a valid ChannelAddress is always zero. The MLBS line is in a consistent known state when not driven by any Device. For 3-pin MediaLB, this is achieved with the required weak pull-down.
| ChannelAddress (1) | Description |
|---|---|
| 0x0000 | BusIdle - Indicates that the physical channel is not being used, not assigned. |
| 0x0002..0x007E | 63 ChannelAddresses - defines the logical channels used in normal operation (3-pin MediaLB) |
| 0x0080..0x01FC | Reserved |
| 0x01FE | FRAMESYNC - MediaLB frame alignment and System Channel ChannelAddress |
| 0x0200..0xFFFF | Reserved |
Note: 1. All odd ChannelAddresses are reserved (LSB must be zero for valid ChannelAddresses).