  An innovative digital Low-Level RF (LLRF) family has been developed at CERN
and deployed on several circular machines. Operation of CERN's PS Booster
(PSB), Low Energy Ion Ring (LEIR) and Extra Low ENergy Antiproton (ELENA) ring
all reaped great benefit from the flexibility and processing power of this new
family. Beam and cavity feedback loops have been implemented, as well as bunch
shaping, longitudinal blowup and bunch splitting. For ELENA, longitudinal
diagnostics such as bunched beam intensity and bunch length measurements have
also been deployed. During Long Shutdown 2 (LS2) the ferrite-based High-Level
RF (HLRF) systems of the Antiproton Decelerator (AD) and of the four-ring PSB
will be replaced with Finemet-based HLRF. This will require a new LLRF system
for the AD and deep upgrades to the existing PSB LLRF systems. This paper gives
an overview of the main results achieved by the digital LLRF family so far and
of the challenges the LLRF team will take on during LS2.
