Data Output - 2.4 English

There are three primary output signal groups for data movement on the MAC I/F:

• tx_macif_ts_id[5:0] indicates the time-slice/client ID currently active on the interface.
• tx_macif_ena indicates that the cycle is valid.
• tx_macif_data_<L>[65:0] contains the PCS data to be forwarded to the network, where <L> represents a data lane.

The tx_macif_data interface consists of 24 separate lanes, each 66 bits (one PCS block) wide. The sequence of channel IDs presented on the transmit data output port directly correlates to the sequence of IDs presented on the channel request side of the transmit MAC I/F. For example, if a request sequence of 39, 27, 30, 5, 6, 2 is issued by the user logic, the receiving user logic can expect returning data with the same tx_macif_ts_id sequence: 39, 27, 30, 5, 6, 2. The delay between request and data is the sum of the DCMAC Subsystem request pipeline, the AXI user logic response time, and then the DCMAC Subsystem transmit independent MAC pipeline.

Although the ID sequence is guaranteed to be preserved, the request gaps (vld deasserted) might shift within the sequence. The ratio of vld on the request interface is matched to the ratio of ena on the data interface, but a deassertion of vld at a particular point in the request calendar is not guaranteed to be matched to a deassertion of ena at the same point in the ID sequence when data is returned.