The output DATA channel can be configured to have no TUSER field, or for TUSER to hold a user field, or a TDM channel index or both a user field and a TDM channel ID. When both user field and TDM channel ID are selected the fields are concatenated with the TDM channel ID in the least significant position. The TDM channel ID qualifies the fields in the TDATA bus for that transfer as belonging to the TDM channel described. See Figure 1 for the structure, because it is identical to the structure for the output DATA channel TUSER port.
The user field is not used nor interpreted by the core. It is provided as a service to allow the system designer to pass information through the core with latency identical to the main datapath (input PHASE channel to output channels). For instance, the user field could contain flags and other ancillary information irrelevant to the DDS, but relevant to some core downstream from the DDS.