RE: Simple analog signaling for an AC adapter
I really think that deciding on a complex bidirectional serial communication methodology is jumping to a solution without a clear definition of the problem.
We should first answer the following questions:
What is the minimum and critical amount of information that must be exchanged between the source and sink to meet the functional, regulatory, safety and end user requirements for product?
We really have not spelled out the functional and usability requirements for this universal adapter/sink combination.
Is the end goal that everybody carries on of these in their pocket? Will there be one in every building, one in every room, or one for every AC outlet in existence?
Each of these scenarios will have drastic effects on the requirements of the product/standard and the environmental impact of creating the standard.
We should list all this information and then determine the least expensive and most reliable method of exchanging the required information after evaluating alternatives. We seem to be jumping straight to high speed communications is required.
We could easily define a simple low cost baseline scheme that would allow for inexpensive limited functionality adapters. The added complexity winds up on the sink side as it would have to recognize both methods of adapter identification. For notebook computers at least a simple method (like the current HP or Dell method) would add negligible cost to the sink but potentially save significant cost to the source. Reliability and cost are the reasons Dell and HP both chose the methods we implemented and we have years and many millions of systems in the field to attest to these methods capabilities and reliability. Unless the problem the work group is solving is significantly different why are these solutions not acceptable for consideration?
I also think we need a lot more development around the requirement/assumption that every adapter must work with every sink. If full functionality is required for any device and any sink then we can only have one source power capability and communication is not really required. Every adapter is just a large 130W brick. If this is not the case then we need to start with defining a minimum source power capability the minimal level of functionality for any sink when connected to this minimal source.
Regards,
Gary Verdun
Technology Strategist
Dell | Office of the CTO
office + 1 512 723 6251, fax + 1 512 723 9929
CTO Office on One Dell Way
-----Original Message-----
From: upamd@xxxxxxxx [mailto:upamd@xxxxxxxx] On Behalf Of Tomlins, Garry
Sent: Wednesday, December 08, 2010 6:20 AM
To: Piotr Karocki; upamd@xxxxxxxx
Subject: RE: Simple analog signaling for an AC adapter
I agree with Lee and Arjan:
This is heading down a path of unnecessary and complex functionality that leads in turn to a complex and expensive implementation. I beleive it will not be attractive to the major equipment ODM's who will need to adopt this if it is to be a success.
We should have a simple analog low cost option.
In my experience in servicing the adapter market for high volume electronics adding a pin, a wire, a resistor a pin to an IC is a big deal - let alone a separate communications system!
My vote is for a simple analog option as described. I believe this will have a good chance of adoption and would be a success for the project.
Garry
Texas Instruments (Cork) Limited, Registered in Ireland under Registration Number: 294554, Registered Office: Riverside One, Sir John Rogerson's Quay, Dublin 2
-----Original Message-----
From: upamd@xxxxxxxx [mailto:upamd@xxxxxxxx] On Behalf Of Piotr Karocki
Sent: 08 December 2010 11:50
To: upamd@xxxxxxxx
Subject: Re: Simple analog signaling for an AC adapter
I don't agree with Arjan.
We could either "describe current situation" or "shape the future".
Our standard could allow resistor-based "communication", something, something, and full communication (required voltage etc.).
But as one of goals is to allow to connect every device to every supply (and, in near future, connections in form of grid; power hubs, power storage etc.), every supply has to have full communication option. Making provision to understand simpler communication (as resistor based) makes supply more costly.
Say, we have hundred million devices. Half of them - resistor based communication, and tenth of them - full model of communication (4/10 of them some 'in-between' form).
Or, we could force whole 100 000 000 devices to have full model of communication.
But it is the only way to make this full communication cheaper - as it would be "more mass" production. It would be ONE standard...
And the only way to make possible to connect device from 2010 to power supply from 2050 or vice versa. This scenario is not impossible - when standard becomes "grid version"... How often you change wiring in your house?
________________________________
From: upamd@xxxxxxxx [upamd@xxxxxxxx] On Behalf Of arjan strijker [arjan.strijker@xxxxxxx]
Sent: Wednesday, December 08, 2010 12:26 PM
To: Atkinson, Lee; Bob Davis; upamd@xxxxxxxx
Subject: RE: Simple analog signaling for an AC adapter
I agree with Lee that UPAMD should also support low cost devices.
A simple resistor to ground inside the device could tell the adapter what voltage it requires.
More sophisticated device can still do power negotiation etc.
With regards,
Arjan Strijker
From: upamd@xxxxxxxx [mailto:upamd@xxxxxxxx] On Behalf Of Atkinson, Lee
Sent: Wednesday, December 08, 2010 12:08 AM
To: Bob Davis; upamd@xxxxxxxx
Subject: Simple analog signaling for an AC adapter
Bob, here is a quick presentation on the method that HP uses for signaling from the adapter to the notebook. We've had this system in place since 2005 or 2006, and have shipped maybe close to 150million systems that use the common "HP Smart" system (including notebooks, all in one desktops, and small form-factor desktops).
My suggestion is that we at least baseline a system that will allow some scalability of the communication method; at least, allow very low cost devices to connect to a UPAMD power source and work reliably even if their functionality is limited. I'm not sure that a lot of simple devices that would use UPAMD have a need for all the messages that the adapter could provide, or would be able to negotiate variable power consumption. I think we all agree, there is very little precedence for using sophisticated signaling in the common DC powered devices now in the market. Though I agree the simple methods are limited, if we can deliver a scalable solution there will be fewer reasons for the industry to not adopt UPAMD.
Thanks again--Lee