30.9.1.4 RxStatus Bytes

The MediaLB RxStatus field is eight-bits wide and all odd values are reserved; therefore, the LSB of RxStatus is always zero. Receiving Devices must place RxStatus on the MLBS line after the Tx Device command byte (Command). The RxStatus status responses are divided into two categories: current state and feedback. The current state RxStatus indicates the status of the Rx Device in the current physical channel, whereas the feedback RxStatus is a response to a Command in the previous logical channel. For Normal responses, only the ReceiverProtocolError is a feedback RxStatus byte. All System responses are also feedback RxStatus bytes.

Two types of MediaLB status responses are defined: Normal and System. Normal status responses are sent by the receiving MediaLB Device (or Controller) in the non-System Channels. System status responses are sent by the receiving MediaLB Device in the System Channel.

For synchronous data reception, the Rx Device does not drive a response. For 3-pin MediaLB, the pull-down resistor on the MLBS line implements the ReceiverReady response automatically (cannot be delayed or stopped).

For control or asynchronous packet reception, the Rx Device responds to a control or asynchronous command with ReceiverReady if it can accept the quadlet on the MLBD line. If the Rx Device cannot accept the quadlet, then it will respond with a status of ReceiverBusy. If the Rx Device needs to stop or cancel the packet transmission, it can respond with a status of ReceiverBreak, in which case the Tx Device must stop transmitting the current packet.

When the Rx Device recognizes an error, the ReceiverProtocolError status response is sent in the next physical channel that is part of the logical channel. The status response of ReceiverProtocolError is issued by the Rx Device under certain conditions, see Data Transport Methods for details.