BRAHMS Data Acquisition
Trigger Board
The BRAHMS trigger board is a prototype VME board used to initiate TPC readout. It also provides the required clock signals for the FEE boards. The trigger board will be used for the initial testing of TPC readout. It provides trigger and abort commands required by the readout board to initiate/abort conversion of SCA contents in addition to clocks used by the FEE boards.
The board can be configured via 4 user programmable registers(R0-R4). The registers can be accessed by single byte read/write operations using extended I/O (0D & 09). The baord occupies 64K of the address space and its base address can be configured by 16 switches (A16-A31). Trigger/abort commands can be initiated in three ways: External NIM/ECL signals, setting the go/abort bits in R2, and by pushing the Trigger/Abort front panel buttons.
Register Specification:
- R0- Specifies the trigger command
- R1- Specifies the abort command.
- R2-
- Setting bit 0 results in the trigger command to be sent once.
- Setting bit 1 results in the abort command to be sent once.
- R3-
- Bits : interrupt level.
- Bit : Enable interrupt if set.
- Bits : Vector.
- Bit 6: Indicates whether front panel NIM/ECL trigger is set.
- Bit 7: Indicates whether front panel NIM/ECL abort is set.
I/O Signals:
- Inputs:
- External trigger (ECL/NIM)
- External trigger (Push Button)
- External abort (ECL/NIM)
- External abort (Push Button)
- External RHIC clock (NIM,jumper selectable ext/int)
- External SCA clock (NIM,jumper selectable ext/int)
-
- Outputs:
- RHIC (ECL/NIM, used monitor RHIC/SCA phase diff)
- SCA (ECL/NIM, used monitor RHIC/SCA phase diff)