CAEN
Electronic Instrumentation
UM3148
–
DT5730/DT5725 User Manual rev. 2
35
Trigger Coincidence Level
Operating with the default firmware, the acquisition trigger is a board common trigger. This common trigger allows the
coincidence acquisition mode to be performed through the Majority operation.
Note:
From AMC FPGA firmware release >
0.1
, it is possible to program the self-trigger logic as described in §
Self-
Trigger
.
Enabling the coincidences is possible by writing at register address 0x810C:
-
Bits[3:0] enable the trigger request signals to participate in the coincidence;
-
Bits[23:20] set the coincidence window (T
TVAW
) linearly in steps of the Trigger clock (8 ns);
-
Bits[26:24] set the Majority (i.e. Coincidence) level; the coincidence takes place when:
Number of enabled trigger requests > Majority level
Supposing bits[3:0] = FF (i.e. all the 4 trigger request are enabled) and bits[26:24] = 01 (i.e. Majority level = 1), a board
common trigger is issued whenever at least two of the enabled trigger requests are in coincidence within the
programmed T
TVAW
.
The Majority level must be smaller than the number of trigger requests enabled via bits[3:0] mask. By default,
bits[26:24] = 00 (i.e. Majority level = 0), which means the coincidence acquisition mode is disabled and the T
TVAW
is
meaningless. In this case, the board common trigger is simple OR of the signals from the enabled channels pairs.