DUNE will be a long baseline neutrino experiment with a broad physics program, including
neutrino oscillation, proton decay, and supernova studies. The detector, located 1,500 m (4,850 ft)
underground at SURF, South Dakota, will be 1,300 km (810 mi) away from the ultimate 2.4 MW
proton beam source at Fermilab. Four far detector modules, of 17 kt total mass of liquid argon
each, will produce ionization data at a rate of 1-2 TB/s per module, while in total 30-60 PB/year
can be permanently stored. The data reduction occurs in real time via triggering the collection of
data only for interesting detector regions and time windows, which are identified by using beam
timing and isolated energy depositions (trigger primitives) as seeds to more complex selection
algorithms. An active and rigorous prototyping program has been carried out to tackle the most
challenging task of trigger primitive finding. This contribution presents the design and operational
performance of a trigger primitive generation (TPG) algorithm implemented on FPGAs using the
ATLAS FELIX readout interface in the DUNE Trigger and DAQ system. Although in parallel a
software-based TPG was developed and delivered as the baseline solution, we demonstrate that the
FPGA-based system was successfully integrated and put into operation. We describe the firmware
TPG pipeline, its verification in software with an emulation approach, and we present the results
obtained from a sample of real muons collected during various tests of the first detector prototypes.