Speaker
Description
Summary
Each CARLOSrx is a board of remarkable dimension, 9U x 400 mm VME, which will be
inserted in a VME crate situated in a counting room during the run of ALICE
experiment.The most important tasks of CARLOSrx are to receive data from SDD
detectors and send them to ALICE Local Data Concentrator (LDC) for the correct
reconstruction of the acquired events.
Each CARLOSrx communicates with the front end electronics via single mode optical
fibers, in particular way the hardware configuration is able to download the
configuration, clock and to receive the events for 12 SDDs detectors through 36
optical. To do that on the CARLOSrx board is mounted the CERN SIU board of the
Detector Date Link (DDL) developed for the ALICE experiment. In the same time the
board includes the CERN TTCrq mezzanine card that is used for trigger information,
clock and busy management with ALICE Local Trigger Unit (LTU). The power supply and
firmware configuration for this board is provide by VME bus.
CARLOSrx is composed principally of 4FPGAs (three process the data coming from
detector and one handle the VME bus) and 4 FIFO hardware (256 Kword x 32 bits) that
buffer the data during the operations of board.
The CARLOSrx firmware has been tested first in Bologna and Torino and now at CERN
for long time and is able to send JTAG instructions and clock to all front end
electronics, receive data coming from 12 modules (one module is composed by one
detector and the front end electronic needed to digitalize and send data to
CARLOSrx), pack and label data and finally send them to a LDC.
Each CARLOSrx was connected to 6, 8, or 12 modules, and it was able in every
situations to send data correctly to LDC; the trigger rate with 12 modules connected
to the board was 90 Hz producing a throughput of 160 MB/s, without compression. Every
single event acquired was checked and no error was found.
Now it is under test a new firmware where has been implemented new features like,
modularity with granularity 1, so CARLOSrx is able to receive data coming from one or
more modules at the same time (this important feature permits CARLOSrx to eliminate a
module with problem and continue to acquire data), error management. In this way
CARLOSrx is able to reject events: this command is sent from the trigger system.
Moreover a RS232 interface has been developed to debug the board during data
acquisition (a custom software takes the control of RS232 port of PC in this way is
able to send some commands to CARLOSrx and check the value of some registers and
signals during the run).
A custom software has been developed to analyze the data produced by CARLOSrx. This
software is completely automatized and it is able to find eventual errors caused by a
wrong behavior of CARLOSrx and or front end electronics.
