Minutes of Weekly Meeting, 2012-01-23

meeting called to order @ 11:05am EST

1. Roll Call:

Brian Erickson
Carl Walker
Adam Ley
Eric Cormack
Brad Van Treuren
Heiko Ehrenberg
Richard Foster [joined 11:10am]
Tim Pender [joined around 11:20am ?]
Harrison Miles [joined around 11:25am ?]

Ian McIntosh
Patrick Au
Peter Horwood

2. Review and approve previous minutes:

12/12/2011 minutes (draft circulated 12/12/2011)

  • no corrections noted;
  • Heiko moved to approve, Brad seconded; no objections -> minutes approved;

01/09/2012 minutes (draft circulated 01/10/2012)

  • corrections:
    • "ha" -> "has"
    • [???] -> [Tim]
  • moved by Brad with those corrections, seconded by Heiko; no objections -> minutes approved with corrections;

01/16/2012 minutes (draft circulated 01/17/2012)

  • motion to approve with the additional link (Swabota presentation) Brad sent out via email;
  • Brad moved, seconded by Eric, no objections -> minutes approved with added link;

3. Review old action items

  • Adam proposed we cover the following at the next meeting:
    • Establish consensus on goals and constraints
    • What are we trying to achieve?
    • What restrictions are we faced with?
  • All: do we feel SJTAG is requiring a new test language to obtain the information needed for diagnostics or is STAPL/SVF sufficient? see also Gunnar's presentation, in particular the new information he'd be looking for in a test language

4. Discussion Topics

  1. Extending the Primitives descriptions to address 2-wire topologies
    Brad shared a pruned down slide set of the primitives, presenting an overview of each of the slides as a refresher to the group:
    - slide "Path Selection Primitives"; general overview;
    - slide "TAP Bypass Element"; would need to be pruned down for 2-wire interface
    • [Brad] I open the floor up for discussion now on what we feel we are going to need to support a 2-wire interface
    • [Heiko] port requirements depend on which 2-wire interface we are talking about; e.g. for dot7 we are talking about a clock signal and a multiplexed TMS and data signal
    • [Brad] I think for now we should focus on 1149.7, later we can discuss other 2-wire interfaces if needed;
    • [Eric] that makes sense
    • [Heiko] so, we would need to trim down the interface on this slide to 2 wires, or we could create a new primitive that converts a 2-wire interface into a 4-wire and back;
    • [Brad] we may need such a primitive, too, but for now we should focus on the requirements for primitives directly supporting a 2-wire interface
    • [Brad] so, for dot7 our PTDI in this slide would combine PTMS and PTDI ?
    • [Heiko] I think it should also include PTDO if the primitive should really show a 2-wire interface
    • [Brad] So are we needing something like a PTMS/Data In and a PTMS/Data Out and a PTCK?
    • [Adam] I believe you are looking for the dot 7 terminology of TMSC and TCKC
    • [Brad] So we are needing PTMSCI and PTMSCO and PTCK?
    • [Adam] The PTMSC needs to be able to be bi-directional in the strictest 1149.7 sense
    • [Adam] Bypassing must be done in a way that is cognoscente of the direction of TMSC
    • [Tim] Does the device have a buffer for TDO that gets eventually read by the host?
    • [Adam] perhaps we should have a 1149.7 tutorial;
    • [Adam] I don't have that ready for today, but could give one in the future
    • {Adam began to provide an overview of 1149.7's use of the TMSC and TCKC signals and how they can be used for the most common protocols}
    • [Adam] Bottom line is all devices need to see a copy of PTCKC and PTMSC
    • [Heiko] to the group: do we feel it would be beneficial to go through a dot7 tutorial?
    • {there was broad agreement that this would be beneficial and very welcomed}
    • [Heiko] Adam, would you be willing to prepare such a tutorial for a future meeting?
    • [Adam] yes, of course; it may take more than an hour, though, depending on questions and the topics of interest;
    • [Heiko] I’ll ask Ian to schedule a dot7 tutorial for a couple future meetings
    • [Adam] we may want to start with a tutorial in one meeting and see how things are going;
    • [Heiko] sounds good; does it make sense to discuss these primitives further without a dot7 tutorial?
    • [Brad] that’s what I’m debating in my head;
    • [Brad] so, what I’m hearing is that PTCKC (unidirectional) and PTMSC (bidirectional) would be needed on left hand side in a pure dot7 environment;
    • [Adam] I can see there are 2 types of primitives needed for the 2-wire interface
      • Buffer (that may need to be protocol aware)
      • Bridge from .7 to .1
    • [Tim] Is TCKC unidirectional?
    • [Adam] Yes, but TCKC has a quirk in it when a controller has to go thorugh an escape sequence, TCK actually becomes a data path
    • [Adam] The 1149.7 standard actually describes the translators between .7 and .1 as:
      • .1 to .7 Adapter
      • .7 to .1 Adapter
    • [Adam] According to the standard, all the 2-wire interfaces to the devices use a .7 to .1 Adapter to gain access to the specific 1149.1 TAP Controller addressed inside the device
    • [Tim] How many address bits are supported?
    • [Adam] There is the Device ID which has 27 bits of addressing per device. Then there is the nodeID which supports up to 256 nodes or an 8 bit field.
    • [Brad] Is that in the entire hierarchy?
    • [Adam] Yes. However, there are ways to create multiple hierarchies. Controlling between them is a different problem.
    • [Harrison] Remember .7 was created by the mobility guys who don't have a lot of devices. Their main goal was to be able to support debug and emulation.
    • {the following five slides Brad presented at the beginning we did not specifically discuss further during this meeting}
      • slide "Simple Linker";
      • slide "TAP Gating Element"; (can be used to represent gating logic of ScanBridge or ASP, for example)
      • slide "Port Addressing via 1149.1 data register"
      • slide "TAP Controller used as Linker controller"
      • slide "TAP Controller used as Combined Gateway and Linker controller"
  2. Q1 2012 Newsletter
    • [Brad] I emailed out a proposal for the newsletter that proposes we have an article about the 2-wire primitives. It is not a "How To" article, but instead begins to raise the issues one needs to think about. See the email for further detail of the proposal.
    • [Eric] I think this is a good idea
    • [Heiko] perhaps even with a link to a forum topic for further discussion?
    • [Heiko] Any other topics?
    • [Eric] should we mention the gateway issues again? How about talking about the 2-wire primitives?
    • [Brad] I don't think we really got started on that discussion yet. We keep trying, but never get to it.
    • [Eric] How about the relationship of SJTAG to some of the other standards like P1687? (put in a note that SJTAG won’t be stand-alone but will be considering other standards)
    • [Heiko] If people have any additional ideas, even for future newsletters, please send an email to Ian or to the whole group.

5. Key Takeaway for today's meeting

  • PTCKC (unidirectional) and PTMSC (bidirectional) would be needed on left hand side in a pure dot7 environment and would need to be visible on the right side;
  • there seem to be 2 types of primitives needed for the 2-wire interface (buffer and bridge)

6. Schedule next meeting

- January 30
- same schedule in February (Monday’s at 11:00am EST)
Eric will be out on Feb 6 and Feb 13
Heiko will be out Feb 27

7. Any other business


8. Review new action items

  • Adam: will prepare a 1149.7 tutorial
  • Ian: to pick a meeting date for that tutorial (Adam needs a few days advance notice)

9. Adjourn

Eric moved, seconded by Brian
meeting adjourned at 11:58am EST