30.9.1 Link Layer

The MediaLB link layer uses the concept of ChannelAddress, Command, RxStatus, and Data to transport all MOST Network data types and manage MediaLB.

These terms are defined as follows:

• ChannelAddress:

A 16-bit token, which is sent on the MLBS line by the MediaLB Controller at the end of a physical channel. A unique ChannelAddress defines a logical channel and grants a particular physical channel to a transmitting (Tx) and a receiving (Rx) MediaLB Device.

• Command:

A byte-wide value sent by the transmitting (Tx) MediaLB Device on the MLBS line at the start of a physical channel. This command byte indicates the data type and additional control information to the Rx MediaLB Device. The Tx Device also outputs data on the MLBD signal during the same physical channel that Command is sent.

• RxStatus:

A byte-wide value sent by the receiving (Rx) MediaLB Device on the MLBS line, after Command is sent. This status response provides a hardware handshaking mechanism and signals other control information, such as transmission errors, back to the sender.

• Data:

The physical channel contains Data and is sent by the Tx MediaLB Device during the same physical channel in which Command is sent. This physical channel data must be transmitted left-justified, MSB first, most significant byte first. Note the Rx Device might return a status of busy, wherein the Tx Device must retransmit the same data in the next physical channel associated with the logical channel.

To dynamically configure ChannelAddresses for logical channels, a DeviceAddress can be pre-defined for MediaLB Devices. The DeviceAddress is a 16-bit address used in the System Channel with the MLBScan command to detect which MediaLB Devices exist.