A possible implementation of a detector specific extension of the FELIX firmware for the ITk Pixel sub-detector

For the ATLAS Phase-II upgrade, a completely new all-silicon inner tracker is planned, which will be read out at higher bandwidth due to finer granularity and higher occupancy. At that point, the detector readout will be switched to the new ATLAS wide readout system focusing on the usage of the GBT protocol and introducing the FELIX concept. While the ITk Pixel sub-detector allows the usage of the GBT protocol on the downlink path, it needs a different uplink protocol due to certain constrains. This work shows how a detector specific extension of the FELIX firmware could look like and which blocks are needed for the ITk Pixel sub-detector.