ATLAS pixel detector: Readout upgrades for Run2 and beyond

For a few years, and in major extent in the upcoming future, a series of upgrades of the Large Hadron Collider at CERN have been pushing to the limit the ability of the present detector hardware to efficiently collect data. It is therefore necessary, for most of the detectors subsystems, to keep pace with this development and to foresee the future challenges of high energy physics. The pixel detector of the ATLAS experiment is not excepted and, together with the implementation of a new detector layer in addition to the existing ones, it is necessary to upgrade the data acquisition system (DAQ) of the detectors used efficiently until now to cope with the increased instantaneous luminosity and to avoid harmful pile-up effects.