Abstract : In nuclear physics, the interaction between the ion beam and the target produces a a large amount of events. Some of these events have no interest for the studied physical phenomenon ; the useful events are sorted using a trigger. We have studied and realized a new trigger suitable for the GANIL (Grands Accélérateur National d'Ions Lourds) experiments. After an overview of the triggers used up to now at GANIL, we give the main features of the new trigger (GANIL Master Trigger, GMT) such as modularity, universality and versality. After a description of the trigger operating modes, we depict the trigger realization steps. The trigger informs about fired detectors in a beam to target collision but gives no information about timing, nevertheless the timing is a very important piece of information if the trigger analysis duration in several times greater than the beam period. We suggest a timing measurement structure (Time to Digital Converter, TDC) able to eliminate this imprecision. The Dead time, the low level intégration and the consumption contraisnts lead us to prefer a digital architecture based on a digital counter associated with delay lines. Simple equations are given in order to define the operating area of the TDC. This area depends on the clock duty cycle and the delay line taps. Measures of Differential Non Linearity (DNL) for different time résolutions (1 ,2, 5 and 10 ns) allow to establish the limits of this system and to underline some solutions to improve these features.