ClusterAlg.gif (577 bytes) The ATLAS Level-1 Calorimeter Trigger

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ATLAS-UK Level-1 Calorimeter Trigger Meeting

Thursday 27 February 2003 at RAL

Present: Bruce Barnett, Ian Brawn, Eric Eisenhandler (chair), John Garvey, Norman Gee, Tony Gillman, Stephen Hillier, Murrough Landon, Gilles Mahout, Viraj Perera, Weiming Qian, David Sankey, Peter Watkins


Click this side                               Click this side
for summaries                                for slides (pdf)
CMM hardware and firmware status........................Ian
ROD hardware and firmware status......................Viraj
TTC, TCM, VMM etc. status.............................Viraj
ROD test status.......................................Bruce
CPM hardware.............................Gilles for Richard
CPM tests............................................Gilles
CPM timing calibration techniques.....................Steve
Serialiser and loss of link.............................Ian 
Online software
Software summary.............................Bruce/Murrough
Recent meeting highlights
Database and Monitoring workshops........Murrough (DB)(Mon)
ATLAS week.............................................Eric
General discussion
What test hardware is needed, and where; UK tests; long-term schedule
Any other business
Date of next UK meeting


CMM hardware and firmware status - Ian Brawn (slides)

Ian presented the status of the current and next generation of CMMs. The testing of the current CMM has finished, bar one minor firmware bug in the VME control CPLD. For the next generation of CMM, five PCBs will be manufactured. Initially, two will be assembled. Documentation needs to be updated as some registers have been added. Commissioning of these modules should begin in April. Firmware for the Jet versions of the CMM is being developed by a collaboration of RAL, Mainz and Stockholm. Note that licencing under EuroPractice needs to be sorted out.

ROD hardware and firmware status - Viraj Perera (slides)

Viraj summarised the status of the ROD firmware (see slide 1) and the modules (first item, slide 2). Specifications for JEP CMM firmware (jet, energy) are still lacking.

TTC, TCM, VMM etc. status - Viraj Perera (slides)

Viraj presented a table (slide 2) showing the status of the various modules. The six new RODs still need G-link Rx cards. TTCrx situation is messy due to multiple versions and some problems with the old ones.

ROD test status - Bruce Barnett (slides)

Bruce said that a second ROD crate had been set up to allow independent testing, but there had been problems with the hardware. The second crate is useful for debugging multi-crate run-control software. He then summarised the status of the various flavours of ROD firmware that are in various stages of testing; see his talk for details.

CPM hardware - Gilles Mahout for Richard Staley (slides)

The first CPM is still being tested. Timing synchronisation can be done using a "1-phase" method; see Gilles' talk below. A few of the backplane links deliver poor quality signals; this is hopefully due to the use of loop-back rather than a real CPM.

The second CPM has connection problems on four of eight CP chips. The board had been tarnished. Although the other two unused PCBs have been cleaned, it was decided for safety and speed to make new ones. The general issue of storing un-assembled PCBs for long periods of time before putting chips on must be investigated in order to understand whether the problem we have is due to poor storage, or is inherent in any long-term storage.

Richard presented ideas for an LVDS source module to be used for large-scale testing (such as final production) of LVDS inputs to CPM and JEM. It would be a 6U module with 88 or 44 channels. Murrough asked about a matching "sink" module. In order to make sure the module is useful for production testing, it should be reviewed when it has been more fully specified.

Finally, he has produced a "fix" for the power-on surges in the crates. It is a combination of filtering and sequential turn-on of different voltages.

CPM tests - Gilles Mahout (slides)

Test of the real time data path between the CP chip and serialiser have been performed. CP chips have been downloaded with a two"1-phase" method, one phase used for the on-board signal and the other one for the backplane signals. The on-board clocks of the CP chips have been rerouted in order to have backplane data and on-board data working correctly within the same time window. Using the TTC broadcast command, the clock has been scanned between the CP chip and serialiser over a period of 25 ns. Four periods of error-free zones have been recorded, and a time window of 1 ns could be found where all data, backplane and on-board, work without error. Signal integrity of the backplane data unfortunately prevents having a wider time window. An overnight run has been performed without errors. New serialiser firmware has also been used to correct the corrupted data observed in previous runs, due to VME access mishandling.

A similar scan has been performed between LVDS data from DSS and the playback memory of the serialiser. A time window of 20 ns has been measured. One serialiser shows a lot of errors due to one faulty LVDS receiver. It appears that one pin of the chip is not connected and will need to be soldered. An overnight run will need to be performed too.

Tests of new firmware normally written for a different speed grade CP chip than the speed grade available on the board have been done. First results are encouraging but it needs a lot more work before validation. Furthermore, we don't know if the device can handle the algorithm too.

In order to have two CPMs fully working for the slice test, successful tests performed so far with the CPM#1 will lead to the assembly of the second CPM with exactly the same components.

During the test of the LVDS, it has been noticed that the DSS does not handle correctly the Brct pins. It should also take into account a strobe in order to validate the Brct pin value.

Testing of the serialiser has been very successful thanks to the access to the firmware source code. Code for a BER test has been written and ChipScope has been implemented within. Access to the source code for all firmware would then be very useful, as seen with the previous example, and also when one of the designer is on holiday and minor changes need to be done.

The next step will be to test the ROC and HIT outputs. This will require more DSSs and GIO cards.

There was a discussion about access to firmware source code. What is asked for is read-only access primarily in order to understand how things are being done. Any changes would only be done to a local copy and only in exceptional circumstances. The master copy would not be touched. One problem to solve is version control in the central archive, and another is the EuroPractice licence. It was generally agreed that this form of access is essential and should be implemented.

CPM timing calibration techniques - Steve Hillier (slides)

In light of recent observations of the behaviour of signals in the CPM, the current firmware calibration algorithms in the serialiser and CP chip are inadequate in certain, not entirely rare circumstances. The problem occurs when no error is seen on all four phases tested, and an arbitrary choice of phase is used. The algorithm could be improved by using extra information about the actual data values, but it may be difficult to fit this more sophisticated algorithm into the FPGAs. Since the algorithms can also be performed in software, and software has more flexibility and time to deal with awkward cases, it may be easier just to implement the whole calibration scheme in software, and not use the firmware calibration techniques at all.

Serialiser and loss of link - IanBrawn (slides)

Ian explained an issue that had been brought to his attention by Richard Staley and Steve Hillier: the Link Loss flag from the LVDS receivers to the Serialiser only becomes active after four consecutive cycles of invalid data have been seen. Therefore, to flag all slices of readout data possibly corrupted by a link loss, it is necessary to delay the readout data by three clock cycles. Ian presented the pros and cons of the required design modification and, after discussion, it was decided that no action should be taken until more was known about the behaviour of the LVDS links.

Online software

Software summary - Bruce Barnett, Murrough Landon

Module services (Bruce - slides): Bruce summarised recent progress and additions to the ModuleServices of the online software.

Software status (Murrough - slides): Murrough presented a brief summary of the software status. The Mainz/Stockholm visit was very useful in pushing things along and highlighting the short term priorities. Work has been done to implement some of these, such as support for setting TTCrx parameters via the TTC, multistep runs, scans of calibration parameters, sets of options groups by run type, etc. This has involved a work mainly in the datbase and module service packages. There is still a lot to do including move to more recent OS and Online software versions.

Dave Kant has started work on customising the Online Event Dump for our ROD fragments. He has produced a requirements document. We should discuss this in a wider forum.

Recent meeting highlights

Database and Monitoring Workshops - Murrough Landon (slides: DB, mon.)

Murrough mentioned two working groups (on monitoring and on error handling and fault tolerance) and the recent database workshop. The database workshop mainly concerned the conditions database, not the configuration database. Murrough gave a talk on level-1. A fuller report will be presented at the imminent Mainz meeting.

ATLAS week - Eric Eisenhandler

Eric gave a brief summary of some relevant items presented at the ATLAS week.

General discussion

What test hardware is needed, and where; UK tests; long-term schedule

Norman showed some ideas on subslice tests for the JEP and the CP (slides) and how they evolve into the full slice, including some estimates of what is needed for JEM testing (slide), as well as test modules (slide) and daughter cards (slide). Some event building will be needed, and that requires a readout subsystem (ROS).

There was a discussion of what is needed to test various pairs of modules in all reasonable combinations, and also where to do them. Most people felt that first testing should be where there is expertise on the modules concerned, but Norman is concerned about how to spread the expertise. Also it is not clear what to do when the expertise on two modules is in different places; the example discussed was CPM to CMM. Eric pointed out that in addition to the slice tests going "vertically" through the system, there is a need for systematic "horizontal" testing; the obvious example is the backplane, where a CPM and/or JEM in combination with a CMM must be put into every single slot and all possible connections checked for correctness and crosstalk. With subsystem tests at RAL this could proceed in parallel at Birmingham.

CPM to ROD could be done as soon as some software is ready.
CPM to CMM would be better with a new module, and also needs software; might be in May. Venue might depend on how earlier work goes at RAL and Birmingham.
CMM to ROD has been done but further work needs software.

It was also pointed out that tests could be done as if in a test beam, with intensive work over a period of a few (say three) days; the location is then not so critcal and might depend on who had got through preceding work first.

Any other business


Will be arranged after the Mainz joint meeting.

Eric Eisenhandler, 11 March 2003

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