SVN:  http://gauss.bu.edu/svn/common-atca-blade

== Reference Material

* [http://ohm.bu.edu/~hazen/edf_joule/PICMG/PICMG-3.0-R3.0_withErrata001.pdf ATCA spec] (password)
* CMS ATCA use: [http://ohm.bu.edu/~hazen/CMS/TrackTrigger/IN2018_002.pdf IN2018_002.pdf]
* CMS DTH spec: [http://ohm.bu.edu/~hazen/CMS/TrackTrigger/IN2018_001.pdf IN2018_001.pdf]
* [[Carrier specs]]
* [[ZYNQ DBS]] - Zynq daughterboard information
* [http://ohm.bu.edu/~hazen/DataSheets/ATCA/ENG_DS_3-1773445-8_0707.pdf TE Connectivity ATCA brochure]
* Parts parts parts
 * TE 1766500-1 Zone 1 connector
 * TE 6469001-1 Zone 2 connector
 * TE 1-1469373-1-ND Guide module
 * Schroff 20818-160 front panel/handle kit
 * Elma 66-536-28 panel
  * 81-300-00 and 81-301-01 handles
  * 81-088-1 microswitch

Consider making mezzanine board 7U high (277.8 mm, see [https://en.wikipedia.org/wiki/Eurocard_(printed_circuit_board) Eurocard info]).  
Depth probably non-standard ~ 200mm as standard depths 160mm and 220mm are not convenient.

=== P23 Connections (CMS only)

|| P23 Row || Port || Pair || CMS Function ||
|| 4       ||  0   || Tx   || LDAQ out 10Gb/s ||
|| 4       ||  0   || Rx   || LDAQ in 10Gb/s ||
|| 4       ||  1   || Tx   || Reserved STDIO  ||
|| 4       ||  1   || Rx   || Reserved STDIO  ||
|| 3       ||  2   || Tx   || TCDS2 Out (throttling, TTS+)  ||
|| 3       ||  2   || Rx   || TCDS2 In (timing, TTC+) ||
|| 3       ||  3   || Tx   || Precision Clock**  ||
|| 3       ||  3   || Rx   || LHC Clock    ||

** Reverse direction from standard!

This is from [http://ohm.bu.edu/~hazen/CMS/InnerTracker/jhegeman_006_temp.pdf this draft] of the document "CMS ATCA Crate Specification and Hub- and Node Board Requirements"

Meetings:

* https://indico.cern.ch/event/738681/ (2018-06-20)

'''2018-05-31'''

Thinking about a common blade for ATLAS L0MDT and CMS IT-DTC. \\
Issues with the current ATLAS design:

* FMC stacking height at 8.5mm is too high

Issues with the current CMS design (Cornell one):

* Really don't like the interposer concept with metal plates, springs etc
* Prefer stand-alone mezzanine card operation

Plus, there are two different blade designs for no obvious reason.

First, looking at low stack height connectors, but not Z-ray.  
(See Samtec [http://suddendocs.samtec.com/literature/samtec-high-speed-b2b-design-guide.pdf guide])
Samtec families with low stack heights:

|| '''Family''' || '''Series''' || '''Stack Height''' || '''Notes''' ||
|| Sea-Ray || [https://www.samtec.com/products/lpam LPAM]/[https://www.samtec.com/products/lpaf LPAF] || 4mm ||
|| Edge Rate || [https://www.samtec.com/products/edm6 EDM6]/[https://www.samtec.com/products/edf6 EDF6] || 5mm ||
|| Q Series || [https://www.samtec.com/products/qth QTH]/[https://www.samtec.com/products/qsh QSH] || 5mm? || 28 Gbps+, pairs, power ||
|| || [https://www.samtec.com/products/qte QTE]/[https://www.samtec.com/products/qse QSE] || 5mm || 25A GND plane ||
|| Ultra-Micro || [https://www.samtec.com/products/edm6 EDM6]/[https://www.samtec.com/products/edf6 EDF6] || 5mm || 
|| || [https://www.samtec.com/products/lss LSS]/[https://www.samtec.com/products/lsem LSEM]/[https://www.samtec.com/products/lshm LSHM] || 5mm ||
|| || [https://www.samtec.com/products/st4 ST4]/[https://www.samtec.com/products/ss4 SSR] || 4mm ||

Below is a figure with dimensions excerpted from the ATCA standard.

|| [[Image(http://gauss.bu.edu/svn/atlas-phase-2-muon-upgrade/Meetings/2018-05-31_EDF/figs/stack_heights.png)]] || Seems as if we can find a 4mm or 5mm solution.  \\ This gives us about 15.7mm above a mezzanine board for components. ||

Next, thinking about the logic.  Is it really that hard to make a common blade?  Here are some thoughts:

* Build a blade to accommodate 3 mezzanine cards
* Plan for only "low speed" mezz-to-mezz communications \\
  (SelectIO or < 10Gbps SERDES)
* Mezzanine cards would have the optics on board along with DC/DC converters and regulators
* Split the CMS IT-DTC into 3 parts
* Eliminate the "blade FPGA" from the ATLAS design and designate one mezz card as "master" \\
  (this could be a different design).

'''ATLAS requirements'''

* Sector logic