Introduction.
The Trigger Control System distributes a first level trigger, provides a synchronous timing inside a spill and broadcasts a relevant information for a data flow control and an event building. The design of the system is based on Time Trigger Control system. The necessity to design a special dedicated system for COMPASS is dictated by a different time scale of implementing the TTC system and start up time of COMPASS experiment. Some components of the TTC system will be available only in a year 2000 i.e. in time when COMPASS will a;ready write first data to tape.
TCS Receiver. Specification.
The TCS receiver is a part of the system which locates on the destination sides or front-end sides of the DAQ. The receiver gets an information via an optical interface, decodes it and distributes it to a local front-end module.
Output signals:
CLOCK - 38.88/40.08 MHz, TTL signal, or unipolar 100K ECL;
Trigger - TTL level, active LOW on the trailing edge of the CLOCK;
RESET - TTL level, active LOW on the trailing edge of the CLOCK;
Beg.of Spill - TTL level, active LOW on the trailing edge of the CLOCK;
End of Spill - TTL level, active LOW on the trailing edge of the CLOCK;
Data Enable - TTL level, when LOW the data[0..15] are valid on the trailing edge of the CLOCK
Data[0..15] - TTL level, data;
Error[0..3] - TTL level, when one of them is LOW on the trailing edge of the CLOCK the error occurs on the serial link.
Power: +5V, 0.3 A; -5.2V, 0.3 A
Data Format:
Two 16 bit wide words follow one trigger signal and form a control word. The words assigned to one trigger come sequentially one after another. The maximum latency of the control data respectively to the trigger is 3usec.
Bit assignments of the control word:
CNT_WORD[0..18] - event number;
CNT_WORD[19..20] - event type;
CNT_WORD[21..24] - detector mask;
CNT_WORD[25..27] -not used
CNT_WORD[28] - reserved for silicon and MSGC readout
CNT_WORD[29..31] - reserved for internal perpose
This page was updated on March
30-th,1998
by igor.konorov@cern.ch