  The JEM-EUSO program aims at detecting Ultra High Energy Cosmic Rays (UHECRs)
by observing the fluorescence light produced by extensive air showers (EAS) in
the Earth's atmosphere. Within this program, a new generation of missions is
being built, including (i) Mini-EUSO that will be installed on board the ISS in
August 2019, (ii) an upgrade to the ground-based telescope EUSO-TA and (iii)
the second super pressure balloon flight (EUSO-SPB2). All these detectors will
have a dedicated trigger system based on a board equipped with a Xilinx Zynq
device that will be able to detect different types of events on three different
time-scales: a microsecond time-scale for cosmic ray detection (L1), a hundreds
of microsecond time-scale for slower events like transient luminous events
(TLEs) (L2), and a tens of millisecond time-scale used to produce a continuous
monitoring, for even slower events like meteors or nuclearites. The L1 trigger
logic for the upgrade of EUSO-TA and EUSO-SPB2 are being developed taking into
account the peculiarity of each detector (optic system, FOV, frame length)
starting from the logic already developed for Mini-EUSO. In particular, every
pixel will have an independent threshold that will be dynamically adapted to
the level of the background; a predetermined condition on the number, the
position and the time distribution of pixels above threshold has to be
satisfied in order to issue a trigger. This contribution will summarize the L1
trigger logics and the tests currently performed.
