In this paper a description of the electronics and trigger system of the High Energy Particle Detector
(HEPD) onboard the China Seismo Electromagnetic Satellite (CSES) and its main characteristics
will be presented. CSES is a scientific mission dedicated to monitoring electromagnetic,
plasma and particles perturbations of atmosphere and inner Van Allen belts caused by solar and
terrestrial phenomena and to the study of the low energy component of the cosmic rays (5 - 100
MeV for electrons and 15 - 300 MeV for protons). The satellite will be launched in 2017 and
will host several instruments onboard: two magnetometers, an electrical field detector, a plasma
analyser, a Langmuir probe and the HEPD. The HEPD, built by the Italian “Limadou” collaboration,
is capable of separating electrons and protons and identify nuclei up to Iron. The HEPD
comprises the following subsystems: detector, electronics, power supply and mechanics. The
electronics, main focus of this paper, can be divided into three blocks: silicon detector, scintillator
detectors (trigger, energy and veto detectors) and global control and data managing. The
trigger system allows switching between several configurations along the orbit to cope with different
fluxes encountered. Each trigger configuration corresponds to different field of view of the
apparatus.