paola.giannetti at pi.infn.it
Thu Mar 24 02:01:52 CDT 2011
I am sorry for the late answer, yesterday I couldn't see e-mails.
I think we cannot use ATCA for the core crates for a lot of reasons that
I already explained, even at the review:
(1) we need early to test the system with the new chip, let's say next
year and it is not realistic to have a new AMBoard, new LAMB and new CPU
interface for the next year. It is very important to be able to measure
currents, capability to work at 100 MHz and with the new chip, before
the end of 2012. We will never do it if we change crate
(2) We are ahead designing the LAMB, the AMBoard and the AMchip. The
suggestions of the reviewers are global, incoherent and do not take into
account the fact that we have already done a lot of work and the budget
will likely decrease not increase: (1) change package for the AMchip,
(2) go to 130 nm IBM instead of 65 nm TSMC, (3) use serial links in the
board instead of parallel buses, (4) get 30% more money (actually if we
go to serial links we need 400% more money)...... all this is totally
not realistic for our plan to be able to measure consumption, cooling
and performances in 2012. Before doing production, we need probably 2-3
AMChip prototypes, it requires time.
(3) using VME we are compatible with the vertical slice, what we do for
the vertical slice is automatically good for the system. If we go to
ATCA all the work we do with the vertical slice is unuseful. We do not
have the manpower.
(4) we already have 2 new VME crates, 2 new CPUs in the lab, we cannot
put them in hold.
(5) we are measuring the consumption and it seems to be less than
expected, may be a factor 2. This reduces a lot concerns about 48 V (2
pins could be enough and separate GND return could be available).
I really think ATCA for the core crate for 2015 is not feasible,
especially if in the same time we have to take data with the vertical
slice. Too much work in a too short time.
It is an interesting option for phase II. The LAMB will be redesigned
for that time, with new chips, new packages and new serial links.
Mel Shochet wrote:
> There are now two suggestions for moving to ATCA. Interboard data
> transfer in the Data Formatter crates could be made easier (the
> alternative being fibers between boards). The Initial Design Review
> committee recommends that we consider ATCA for the core crates because
> of the committee's concern about power (our 48-volt solution) and
> cooling. We will have to respond to this suggestion. (A potential
> disadvantage is ATCA's 8U vs VME's 9U size). Could we have an initial
> discussion of the issue at our meeting in 2 weeks (April 5)? We could
> hear what the DF issues are from Fermilab and what the core crate issues
> are from someone in Italy working on the AM and associated
> infrastructure. Then we can decide on the next steps if any.
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