AUXbus: An Event Driven Bus-based DAQ System

Paper: 138
Session: B (talk)
Speaker: Aloisio, Alberto, Universita' di Napoli "Federico II", Napoli
Keywords: data acquisition systems, event building, special architectures

AUXbus: An Event Driven Bus-based DAQ System

A.Aloisio, S.Cavaliere, F.Cevenini, D.J.Fiore and L.Merola

Dipartimento di Scienze Fisiche - Universita' di Napoli "Federico II"


INFN - Sezione di Napoli

AUXbus is a custom bus-based architecture designed to provide optimum
performances for DAQ systems in HEP experiments.
AUXbus targets this specific application field by featuring event-driven
operations, sparse-data scan capability and random length block transfer
cycles up to 15 MTransfer/s.
AUXbus also includes resources for extensive diagnostic checks and performance
monitoring. Its ability to distribute flow control, synchronization and trigger
signals as well, greatly simplifies the DAQ final design.
AUXbus uses the lines available on the outer two rows of the VME/J2 connector
(64 TTL lines). Precision timing pulses - as trigger signals - are distributed
in differential ECL levels onto the JAUX bus, which has been redesigned from
the original CERN's specifications.
A monolithic backplane which merges VMEbus (A32/D32), AUXbus and the modified
JAUX subsystem has been developed. Careful layout design rules have been
employed to achieve tight control on line impedence for an optimum signal
integrity level. TDR technique has been intensively used to characterize the
AUXbus backplane's lines and to finely tune the PCB manufacturing.
The AUXbus architecture has been adopted by the KLOE experiment at the DAFNE
Phi-factory at Frascati INFN National Laboratories, Italy.
For this experiment we have also designed an AUXbus read-out controller
which is the building block of the KLOE DAQ System.
In this paper we describe the bus management protocol and the monolithic
backplane's features. We also present preliminary test results of our
architecture in the KLOE DAQ framework.