The errant engineer

well we had to ask...

2011-04-11T22:14:00.001-04:00

Didn't we!

Insatiably curious souls that we are, we just had to ask.

Di,

I was just checking my email and noted that I had nothing since last week

from ~~NMRANET~~ NMRANETWG on Yahoo, so I checked, it seems to have disappeared...

Something happened?

at 7:57pm EST today, and the reply:

The sites have been closed.

Didrik

I have corrected my group naming error in the text above, what I crossed out is exactly what I sent to Didrik Voss.

So what do we make of this? Is Didrik basically saying that NMRAnet is dead in his mind? I mean if the working group nos no group to work in what are we supposed to do? Or is he telling us not so subtly that we can all go play in our own sandbox because he has taken control of the NMRAnet sandbox for himself? Or is he merely trying to remove the evidence? Just as well a few full mailboxes of those groups exist around the place then isn't it! At least we haven't lots years of work. Despite the fact that all of the files in those groups are gone now.

Vale NMRAnet

2011-04-11T20:24:00.001-04:00

As of today, April 11, 2011 (and no this is not a late April fools piece) the two currently active NMRAnet discussion group on Yahoo Groups have disappeared! No notice to any of the members. Not even a word to the moderators. One of the moderators went to check why there was no email coming from the list, and guess what he found.

It's actually just a continuation of what has been a pretty torrid history for groups talking about NMRA. Back in mid-2005 David Harris established a group called MRR-LCB - to discuss layout control bus ideas! That group remained active, albeit sometimes sporadically, until mid-2010. Some discussion was entered into on the old NMRA DCC working group, but after the Detroit convention in 2007 a group known as NMRANET-WG-TECH was formed and operated from September 2007 until June 2010 - just before the NMRA convention in Milwaukee in July. Out of a discussion at Milwaukee with two gentlemen who agreed to try and moderate the discussion a new list, NMRANET was established about July 28th 2010 and continued in use until April 6th 2011.

NMRANET-WG-TECH was still alive on Yahoo today as was NMRANET but another group which had a transient life for a few weeks back in the first half of 2010, NMRANET-Applications, and NMRANETWG have now disappeared altogether.

Seems that our friend, one of the VossBros, has been trying to destroy the evidence out there! Or maybe he has decided that only the brothers can agree on what THEY actually want, and so they will handle it all themselves now? Who knows?

Not us! We are just the working group members, interested model railroaders and the interested manufacturers, we obviously don't matter.

NMRAnet falters

2011-04-11T19:06:00.000-04:00

Despite a lot of press indicating that the NMRA board actually approved an NMRAnet physical layer, the NMRA legal people and senior officers say they did not! The erroneously placed information is expected to be removed from the NMRA web site very shortly. In the meantime it has been confirmed that the NMRA Board has in fact issued an invitation for the working group to present to them in Sacramento in July.

I understand that a lot of email and phone contact has been had between the working group and the NMRA to clear up a number of issues. That is now possibly in hand and we can proceed in a more orderly fashion, we hope.

Who would have thought

2011-04-04T19:58:00.002-04:00

That today Texas Instruments would announce that it proposes to acquire National Semiconductor. All of which led me to describe some of the history to a colleague:

TI was one of the first semiconductor companies, and is hugely well established, they acquired Burr-Brown (specialist analog house) some years back and more recently Luminary Micro - the first ARM-Cortex M3 implementor. TI is possibly the largest Digital Signal Processing chip maker and is also the originator of the DLP digital projector technology. Their ARM Cortex-A8 and A9 chips are used in cell phones and console products. Back in the 60's the integrated circuit was invented basically simultaneously by TI and Fairchild.

National was spawned by Sperry with a group of Sperry staff creating National in Danbury CT. In 1965 they acquired Molectro, and gained as employees Dave Talbot and Bob Widlar who were ex-Fairchild and possibly the leading IC designers of the era. In 1967 Chrlie Sporck was hired away form Fairchild and once again the bedevilled raltionship between Widlar and Sprock turned to fire. Then in 1968 National moved to Santa Clara and was well known for poaching staff from Fairchild. with designers like Bob Widlar they soon took the analog market by storm, they were a massive power house in discrete transistors (not power), CMOS logic and specialty chips including a number of early micros. In the end they swallowed up Fairchild (1987) and eventually spat it out again in 1997.

TI ranks 4th in the industry with 4.3% market share and about $30bn in revenue. National now ranks down there, with $1.42bn of revenues last year. The big thing is the massive consolidation of commodity semiconductors houses. In recent years TI and National have slugged it out in the commodity chip market, now we will have to wait and see what synergies work out and which product lines disappear. Two of the great names now rolled into one maybe!

The wide world of LCB's.

2011-03-25T21:57:00.000-04:00

Layout Control Buses that is.

As with any efforts to produce standards, particularly open ones, their has been an attrition of projects in recent years. Layout Control Buses for model railroads are not new, but those that exist now are often based on simplistic and not greatly flexible schemes. Possibly the classic is Dr Bruce Chubbs C/MRI which first appeared in Model Railroader magazine in February of 1985. Based on a simple microprocessor module with an RS-485 or RS-422 interface, connected to a PC, the C/MRI system then uses a series of IO expansion cards to connect to pretty much anything. Updated fairly regularly the Chubb designs are now starting to show their age but are still a viable control system. Information and parts can be found at the JLC Enterprises website.

From the ever industrious MERG group in the UK comes Gordon Hopkins RPC system. Of similar vintage and technology to the Chubb system RPC relies on a series of interconnected interface boards. Having the pleasure of meeting Gordon I can only attest to his keen modelling interest and his designs reflect that. However like the Chubb system it is now getting dated, much of the work on it having been done in the late 90's.

In 2007 or so their again emerged from MERG the CBUS system conceived and developed by Mike Bolton in the UK and Gil Fuchs in California. Based on CAN bus this comparatively new system marks the beginning of the new LCB era. General purpose modules, well connected, using something akin to the producer/consumer model of operation. CBUS has a Yahoo Group as well. The boards are based on PIC controllers with CAN bus. The early boards had some issues with ground bounce and offset, but the later 12V board versions are reported to be somewhat more stable. However the practicve of sharing ground and power for the communications and operation power does detract form the stability of larger layouts. CBUS is a credit to its developers and certainly deserves a look.

OpenLCB arrived on the scene also in 2007 but began life in 2005 when I designed a DCC and accessory system that never saw the light of production. Discussions surrounding this approach stimulated Dr. David Harris and myself to explore further and through our acquaintance with Alex Shepherd in New Zealand we started devising what was at first an object oriented network which transitioned to a producer consumer network as we developed. The principal developers for OpenLCB are myself, David Harris, Bob Jacobsen (of J/MRI) and Alex Shepherd. Their is also an active Yahoo Group. Some hardware has been designed and is in use but much OpenLCB development was done on the Silicon Railway LEDuino (which includes CAN bus, DCC decoder input and rudimentary response signalling, LocoNet interface and the usual serial and USB interfaces) and other Arduino type boards. John Plocher has an Arduino model railway shield.

Don Voss proposed an RS-485 based system (as I recall) which he later moved to CAN bus in 2008 or so. Very little data has been published, but what has can be found linked on the largely outdated NMRAnet website as the S9.5 system.

There have been others, but quite honestly the details are rather vague in my mind right now and I would have to dig back into history. I should also say that I am directly involved with OpenLCB, and I have been a part of the NMRAnet community since essentially before it existed!

Tune in again for some technical discussion very soon.

As Time Goes By...

2011-03-14T20:54:00.000-04:00

A beautiful song, but should it be appropriate to look back on a post that is nearly two and a half years old (April 2008) and realise that nothing has really changed?

Back then I wrote about the NMRA (National Model Railroad Association) and the various attempts at a model railroad layout control bus (LCB) standards formulation. And as I look back over it all I find that nothing has really changed. The on guy who hijacked the process is still trying to bully other participants to his way of thinking whilst at the same time refusing to expose any of his design work, code, or draft standards. His brother happens to be the corporate officer responsible for the standards and compliance process. What a lovely cozy position to be in.

I meant to post these remarks a few days ago, but they got forgotten. However in light of what I wrote earlier today they remain no less appropriate.

If at first you dont succeed, just wait, they will kick you again!

2011-03-14T20:52:00.000-04:00

As of today it seems the news is out. The board did actually consider the matter, and now we know officially. The NMRAnet working group hasn't been told yet, nor have the authors of the document submitted.

NMRANET standard adopted

The board reviewed two versions of S-9.x.1 for the definition of the physical layer of the

layout control bus called NMRANET. The version modified by Didrik Voss, manager of

the Standards & Conformance Dept., was adopted. With this approval, the sponsors for

the other version will be invited to present their concerns to the Board at the Sacramento

meeting. S-9.x.1 was re-designated as S-9.5.1 and will be posted on the NMRA web site.

Several manufacturers of electronics for model railroading have been waiting for this

new NMRA standard so they can adopt it for their product line.

The actual BOD meeting report summary can be found online here.

As well as not being informed even informally about the BOD meeting considerations and vote we have yet to receive our invitation to address the board in Sacramento in July. Let's hope it arrives soon, we need to dust off all the material that we guess wasn't presented to the board in February. But why does it have to be this way?

We don't know in any detail what happened at the BOD meeting, today is the first we know of anything other than the appearance of the S9.5.1 document on the NMRA web site. What is even more galling is that we now know that the NMRA board has sanctioned a document which is a derivative work from material where copyright is claimed by its authors. No permission was sought or granted, no acknowledgement given. It is as though the NMRA feels it is above the provisions of copyright law in the US and Canada (two of the authors are either Canadian or Canadian residents) and the DMCA in the USA. Pretty shabby treatment really when all things are considered.

Back in December 2010 I responded to a help wanted ad placed with Gerry Leone, communications director for the NMRA, for electronics engineers to help with the development of NMRAnet. This request was never sent to the NMRAnet working group list, nor to the DCC working group list. But it was in the NMRA magazine and so I responded. The day after Gerry acknowledged my email I received this response form Di Voss:

John,

You must be the only Electronics Engineer in Canada or, at least, the only one that responds to my help wanted ads.

Since you are already part of the effort, I do not need to provide you a summary of our work.

Didrik

It seems that my work is to continue to provide soundly based, well argued professional work. Seems that my job is to accept being treated like a mushroom, kept in the dark and fed with .... well, I think you know the answer (at least any self respecting Aussie would). I am to toil diligently in the fields, submit my work, have it used to creative a derivative document without permission or acknowledgement, not be told what the considerations of the material submitted are and to just keep on taking it and liking it.

So disheartening, so disillusioning. No wonder nobody wants to play in the NMRAnet or NMRA-DCC sandboxes any more, if this is how we are to be treated. Onwards and upwards OpenLCB!

Why? He asked...

2011-03-04T11:44:00.000-05:00

Would Don want to change the heavily discussed and argued OpenLCB physical layer standard (already voted and accepted within the OpenLCB community) and modify it?

Several of my colleagues at work and elsewhere have been heavily involved with CAN bus for some little time now. So over the last few days a couple of us have used our break time to kick around some ideas in an attempt to figure out why Don was so insistent that these changes be included. All of the comments that I recall related to increasing the number of nodes allowable on a given length network.

Three factors influence the length of the network.

The round trip propagation delay between the two most remote nodes.
Voltage changes due to the intrinsic resistance of the cable and the Rdiff of the individual receivers
Waveform distortion or signal level attenuation due to the effective distributed capacitance of the transmission line.

Cable: The specification as we established it calls for the use of CAT 5e cable, which according to the ISO11801 standard should have nominally 5.7ns/m delay. But this is purely for the cable, it does not include connectors, PCB's with their own intrinsic capacitance and the effects of any common mode chokes or ESD protection devices. Prudent manufacturers may choose to include common mode chokes, ESD clamping diodes or varistors for protection. All of these add capacitance which will increase Vp and reduce the maximum cable length as well as add waveform distortion as alluded to above.

Resistance: We are assuming, that despite their being no explanation of the derivation of the constant in the numerator of the equation, that the VossBros equation assumes a 90 ohm/kilometre resistance. And thats fine, but our concern here is that not only does the VossBros change actually not specify what Ri is, nor does it spell out how that constant was derived. That equation does not appear to take into account any parasitic or stray capacitance introduced by PCBs, connectors, ESD protection or whatever.

Waveforms: Anybody who knows anything about transmission lines knows that rise and fall times are a function of bandwidth. Compromising bandwidth with capacitance means that to get the performance we have to reduce capacitance, which means reducing cable length. If you are to allow users to calculate the maximum network length, or max number of nodes for a given length, then capacitive effects must be taken into account, but in the VossBros documents they are not.

The OpenLCB standard offered to the NMRA (but butchered by VossBros) specified the important maxima, length and number of nodes. Why was that so hard to understand? I have one possible hypothesis. At one point the concept of gateways and bridges was discussed with the S9.5/Voss group. It seems that in their own opinion bridges don't play well with their protocol. Of course we can't offer much more of an opinion because no details of their protocol have ever been published. But that could explain the obsession with maximising the number of nodes. So an S9.5/Voss based LCB could be limited to the 111 or 112 or whatever number of nodes. OpenLCB/S9.6 on the other hand can use bridges and gateways to create much larger LCB's.

de Javu all over again.

2011-03-01T14:54:00.001-05:00

When I wrote a day or so back about the NMRA process for standardising the very first part of their desired NMRAnet little did I know that a decision had already been made. Of course, the usual dictums of common courtesy seemed to have escaped the NMRA Board of Directors and the Standards and Compliance Manager. The working group was not informed. The authors of the document were not informed. The standard merely appeared at some point. The next line on the index page points to the as yet non-existent technical note.

At least in the version finally published some of the material so offended the Standards department manager was restored. But the sad part is that the changes which remain are just as offensive to the technical community. Even more amusing is that what we have asked for over so many months, something that supports the assertions of Don Voss, still hasn't been supplied, nor is it included either in the standard as published, or in the draft TN (the real one we dont know).

The standard suggests that we can adopt CAN bus yet vary it. I wonder if somebody, like Robert Bosch the inventors of CAN bus, has copyright control! The bastardised CAN bus we are presented with sinmply is not CAN bus. The Voss brothers ask that we accept that CAN bus certification of a component is required, but that an essential CAN bus specification, Rdiff(min), must be >20kohm. But Rdiff(min) is only tested to be >10kohm for CAN bus certification. A transceiver manufacturer may, but is not compelled to, state what Rdiff actually is, or the range that may be encountered.

All of this when they went to such lengths to try and justify this variation using data and application notes designed to sell specific products. By including a formula in the standard for determining the maximum theoretical under ideal conditions network length WHICH INCLUDES Rdiff AS A PARAMETER! Well, they sneakily dont say that, they include 20,000 as a constant. When in reality the maximum langth of the network, under those same conditions (or the maximum number of nodes) could be longer or larger if the original equation from NXP were used and the effective Rdiff left in place. Of course, after FOUR years of discussion it is hard to expect such rigour to be part of the standard isn't it?

Like I said, what did we really expect? Procedural fairness? Honesty and technical integrity? Openess of process and procedure? Well, this is the NMRA after all.

Seems some things never change! The NMRAnet saga 3 years on

2011-02-27T21:43:00.002-05:00

When I wrote my post yesterday referring to the debacle surrounding the NMRA and the NMRAnet process I had in the back of my mind that this had been going on for a long time, what I had forgotten was that I posted on the same broken process back in April of 2008, close to three whole years ago. In that post I referred to the process that had been going off the rails routinely for the previous 12 months. Which means this debacle must have been going on for about 4 years now!

Insane.....

And we still can't get a sensible word out of the NMRA process.

During that time an amazing group of people have developed the bulk of a standard series and protocol family known as OpenLCB. Their work and their efforts in the NMRAnet working group have formed the basis of the S9.x.1 standard proposal which has been butchered by the amateurs I referred to yesterday. As a part of that effort I find the last minute unsupported modifications outside of the working group process to be an abomination.

How much longer does it have to go on?

Or maybe it needs to come to a stop now, and like the DCC working group before it, fade into oblivion. Since June of 2009 the DCC community has been split in two. A US based manufacturers group which only admits established large scale commercial DCC manufacturers to its discussions, and a European group which insists that all its meetings will be in Europe and business conducted in German. If the NMRAnet working group persists, then I wonder how long it will be before we come to the same impasse?

In the meantime maybe the "OpenLCB" group on Yahoo groups is a good place for anybody wnating to know what an LCB (Layout Control Bus) really looks like.

When amateurs dabble

2011-02-26T14:32:00.001-05:00

When amateurs dabble in technology we see all sorts of things happen. Some are amazingly good, the Arduino would be an example of that. From small beginnings a group of hackers and hobbyists have changed the face of microprocessor learning and development. A true paradigm shift.

But for the last few months I have spent many hours working to try and bring some sanity to the NMRA (National Model Railroad Association) standards discussion over a model railway layout control mechanism they want to sponsor called NMRAnet.

The development of the scheme was to be co-operative, but never open. However in the end the brother of the Standards Manager for the organisation left the co-operative discussion and took no further part in the working group established by volunteers to develop the scheme. This same former member of the working group then had his brother modify the documents submitted by the working group to include his own favoured changes. Sadly they were generally ill-considered and had the backing of nobody in the working group.

So now we stand at an impasse, two versions of the documents will be put to the board of directors. We wonder which will survive, the original which is sound, rigorous and based on ISO and other standards, or the modified, crippled version, which removes several of the most basic safeguards to the reliability of the network.

Who knows, buyt in teh past it seems tat no matter how ill advised the changes unilaterally proposed by the Standards Manager they have been accepted. Lets hope the NMRA Board of Directors changes their minds this time.

Whatever happened to.....

2010-09-22T08:18:00.000-04:00

In this case, MIPS Technologies.

Based on original academic research done at Stanford from 1981, MIPS was formed in 1984 and until the 1990's was influential as a supplier of CPU chips for a variety of manufacturers, including such names as SGI, Siemens/Nixdorf, Olivetti and many others. Since then MIPS has also been licensing architectures and core designs which became prominent in the set top box, cable modem and router arena. They never made it into the Smartphone/PDA market, long dominated by Intel and ARM.

And now we see yet more advances from ARM, newer cores such as the Cortex-A15 and promised improvements this year and next seem to set the field for an even greater market penetration by ARM.

So I really do wonder, where will MIPS go now?

Its not easy keeping a blog!

2010-09-22T08:04:00.000-04:00

And I am sure a lot of you know that. Between work and family how should I find the time to say things here. Well, I keep finding notes of all sorts of ideas around my desk, so maybe I should just post some of those!

The goalposts keep moving!

2009-11-14T21:46:00.000-05:00

The microprocessor has been with us for some time now, on my radar since 1974 with the release in April 1974 of the Intel 8080 which I first applied only a few months later. So I grew up and was 'educated' before the microprocessor. In those early days the choices were minimal, Motorola introduced the 6800 a little later in 1974. Despite protestations to the contrary that one or the other had some great technical or architectural merit it was really a matter of religion which path you followed. You could make a choice then being comfortable that it would hold good for a few years.

More recently the same religious fervour is evidenced by the proponents for the Freescale (formerly Motorola) 6800/6802/6809 ancestored chips versus Microchips PIC and Atmels much newer 'C' code optimised AVR and megaAVR. Each has its benefits, but logic defies any choice other than the one that I like!

But now the game has a completely new set of rules. ARM, of Cambridge UK, has turned the world upside recently with the introduction of the Cortex-M3 IP core. In a very carefully staged collaboration with Luminary (now part of TI) we saw the introduction of the Luminary Stellaris parts - the first M3's. Now everybody is on the band-wagon! Atmel (ATSAM3 is Cortex M3 based), TI through the acquisition of Luminary, NXP with the LPC17xx series, ST Microelectronics STM32, Toshiba and a new Norwegian startup - Energy Micro. All good viable companies, and don't count Energy Micro out, although only 2 years old they have some well experienced talent from Chipcon (now part of TI) and Atmel.

So now we don't get each manufacturer offering us a new architecture - we get them offering us different customisations and peripheral mixes all based on the same CPU core and interconnection fabric.

Oy vay!

So so so long!

2009-11-08T09:50:00.000-05:00

Has it really been that long? Have I really been that busy! In a word, yes. My current major project has taken enormous amounts of time and effort over the last 6 months or more, so anything else has been sidelined. Those out there who know me will understand just what has been going on.

ENGINEERs and the recession.

Of course for many of us the last 12 months or so have been a tough time. Many jobs have been lost and new openings not always easy to identify. Fortunately I was not amongst the job losers, in fact my employer didn't shed any jobs, the factory and admin staff went onto Jobshare (work 4 days a week paid and then get one day of EI) but the professional staff were presented with a nice 10% salary cut "for the duration". The duration turned out to be April to October. But at the same time we were asked to work harder than ever, during this period I worked a number of weekends and I still haven't had my "summer" vacation. At the same time we are asked to be our most productive many of our employers also cut back on capital investment and even on things like software tools. In an era when engineering salaries are under attack by everyone from transit operators (say a streetcar or subway driver) to local librarians we are being asked to take more responsibility and work work longer hours as many in society are heading the exact opposite direction.

For many years it was the skilled tradespeople and the factory workers who need to work a second job to make ends meet. To that list we can now add engineers. More and more of the engineers I speak to are seeking "contract" work to gain the extra income they need. Of course, this doesn't help the situation of the contract designers already out there does it. It will be interesting to see how the situation of the engineer plays out over the next year or two.

Life has been busy

2009-04-12T11:11:00.000-04:00

Life tends to deal all sorts of interesting cards to us. In the last six months I suppose the economic crisis has consumed most of us, especially those trying to hold onto our jobs! So it has been some time since I wrote anything here, but now I can remedy that neglect.

Altera/NIOS-II

Seems to have been a major focus of my work for much of the past two years. I now have four successful designs under my belt, one is in production, one is going into production now with a third to be in production in the next month or two. The fourth may never see the light of day - that will depend on the speed of another major development project I am working on.

LEDuino

My baby! This is our take on the extremely successful Arduino project. Several volume orders for special applications have consumed a huge amount of time and effort. About Octoboer 2008 we built a large batch of the revision B board which has been very successful. Finally we have had time to implement some CAN bus code for the thing and code for DCC is under way. If you want to know more, keep a watch on this page for more details.

Fairchild changes sampling policy

2008-09-02T21:32:00.000-04:00

After 39 years as a happy Fairchild customer, having even been a franchised distributor at one stage, I went to their website today after mentioning a new I2C buffer from them. I am not sure when I last needed samples from them but it wasn't recently so I haven't been abusing the system. That didn't matter, my application has been REJECTED and I find that Canada is now in Europe because I had to contact EUROPE sales office.

Sorry Fairchild, after 39 loyal years you just blew it. Sadly the company that fostered such talent as Bob Widlar, Gordon Moore, Robert Noyce and Frederico Faggin seems to have some sort of problems with North American designers.

I2C alive and well!

2008-09-02T10:40:00.000-04:00

For many years I2C - the "Inter Integrated circuit Communications" bus has been a staple part of my design diet. For many years Philips/NXP, Analog Devices and TI have provided a nice array of general purpose parts and many specialised devices came with I2C interface.

All went along nicely and quietly for years. But just recently things have changed! Everybody seems to be getting onto the bandwagon. First, the PC world was blessed with SMbus - based on I2C and then we are off. Now there are several new control/supervisory standards based on I2C, ( PMbus for power management, IPMB for chassis management) and with NXP introducing high speed extensions it has all come back into play!

SO how do we make it all work? For starters the old I2C with soft pull-ups just doesn't cut it anymore, the P82B715 and P82B96 from NXP are fine, but they are getting dated and are not as flexible as we might need. SO new things were needed, a search uncovered that Linear Technology had introduced some new parts that offer us some more. And just today I found out that Fairchild have entered the race with this device.

But nothing really satisfied hte needs I had until a colleague pointed out Hendon Semiconductor. Hendon, I thought? Now I know a couple of Hendons, and I was a little surprised when I found that this Hendon is the one in Australia. Then it dawned on me. For many years Philips had run a very successful hybrid plant at Hendon - and this has morphed into Hendon Semiconductor. And their specialty? I2C and bus buffers! In fact they have a range of about 10 parts either announced or upcoming which will provide a match for many applications. A visit to their specialist site at busbuffer.com is well worth a few minutes.

DISCLAIMER: I have no ties with Hendon other than being a very happy user. Their US office have been very helpful and if you look carefully you will see my LEDuino product uses the IES5501.

Open source hardware

2008-08-03T12:29:00.000-04:00

One truism that we see shouted over and over again is "you can't make money in open-source". Of course if you are reading this then it is likely you don't accept that premise. But it is true to say that for many corporations it is not possible to make money out of open-source. In my $$job we do it all the time, we use Linux, we use open-source VHDL and Verilog all the time. It reduces our development cycles, gives us a broad base of support and reduces our costs, at least up front. But as our final products required significant compliance testing and such we could never produce open-hardware the software is an integral part of the operation.

However, take things like Gumstix, Arduino, Wiring, LEDuino, DAISY MP3 player and others proves that the concept of providing a hardware design that can be duplicated is growing. No one individual or even small group might be capable of exploiting a design, but maybe others can. The Economist recently did a piece on open-source which was quite positive. One of my personal motivations for designing open-source hardware is that I am not really a programmer! I can give you really good hardware, and maybe some basic code to run on it, but be darned if I want to spend my life maintaining and enhancing it!

If course I can make money selling hardware, even when I do provide all that is needed to replicate it. How many people really have the skill and resources to produce sophisticated electronics hardware? A bare PCB sold for $20 is cheaper than the time and effort to produce something yourself. So I can make my designs, make some pocket money out of them and you can have the fun of doing things on the boards, sound like fun?

Arduino/Leduino mechanical drawing

2008-07-29T12:14:00.001-04:00

The Arduino concept, and our own LEDuino, have been a great success. But one persistent difficulty I see is the lack of an accurate board outline drawing. At least supposedly "authorative" template I have seen had errors. So based on the Eagle files of the official Arduino Diecimila I created a layer in my EDA package that has the dimensions that as far as I can tell are accurate. This PDF file is a copy of that layer. Unfortunately I do not use Eagle but if you do, feel free to translate my drawing and I can happily post it on my site if you want.

Atmel Xmega - some more thoughts

2008-07-26T08:31:00.000-04:00

Work continues here in the background on a small development platform based on the ATXmega128A1. One very interesting point which becomes salient with these devices is the peripheral multiplexing issue. Until now the functions available on each pin were minimal - you used a pin as IO or you might assign it to a timer, or a UART.

But with the Xmega we have more choices, how many UARTs can we use while using various SPI or TWI ports? Which functionality do we lose by choosing some other function? Lots of fun and something that we have been insulated from in the AVR world.

LEDuino in the wild.

2008-07-25T15:15:00.000-04:00

Well, the first LEDuinos are making their way into the wild. The very first shipment went to Australia. I hope the unit enjoys going back to my home country! Response so far has been very gratifying. We are working on some application examples using the LEDuino specific capabilities, more news soon.

Arduino field to get a new entry

2008-06-15T15:10:00.000-04:00

For some time now my colleagues and I have been using Arduino ( http://arduino.cc ) style hardware based on the Atmel ATmega168 processor and a very easy to use development environment. The Arduino IDE environment is flexible enough for much rapid prototyping work, but simple enough for non-technical people to use, in fact it was originally designed for teaching design students how to build interactive projects.

The more we used the system, the more we liked it. But the more we used it the more we found we were missing some things we take for granted on our more sophisticated development platforms.So why not add some interfaces to the Arduino to make it more usable in a variety of applications?

So we sat down and figured out what we use most commonly. Thus is born the LEDuino.

Buffered I2C bus for longer cable runs and higher bus current operation. So we added an IES5501 bidirectional driver.

We play a lot with designs for model railway layouts. Already we use a lot of DCC, so we figured that a standard DCC decoder input, complete with basic acknowledge facility. So we added that with full galvanic isolation both ways for convenience.

In a number of situations we use CAN Bus. Several developing or proposed model railway layout control busses use CAN, so we figured we could be compatible and give ourselves a simple development platform for that too. CAN is also used in a variety of other fields where we have some professional involvement.

So why the name LEDuino?

Well, one of our engineers develops a lot of LED based technology for architectural, visual effects and signage, he often wants to talk to serial interface devices like the TLC5940 from TI. So we added an entirely custom connector on the bottom edge of the photo, it has a serial interface that is designed to mate with some of our other products. As time goes on some of these products will be added to this range of products.

So this is it, the beginnings of a new range of Arduino inspired technology which is in fact already well proven, well used, and well liked.

The NMRA and NMRAnet - a broken standards development process

2008-04-17T11:08:00.000-04:00

Unless you know me, you wouldn't know that I love model railways and I have been playing with them one way or another since the early 70's. A couple of years ago I developed for myself a concept of hardware mimicking the object oriented software approach. In theory it works nicely. So I went in search of a networking technique to support what I wanted.

I am not sure how, but I teamed up with a guy from New Zealand (a professional programmer and accomplished embedded software developer) and one from British Columbia (a medical Doctor of all things with a CS degree before his time in medicine and a life long interest in modelling too. Turns out they also had some ideas about this sort of thing too. Then we got hijacked. Some other people started to participate in the list and decided that cheap, simple, unscalable and ready tomorrow technology is all that the model railroad industry and hobby needs.

Then someone tried to float a standard into the National Model Railroad Association (of the USA) to create an NMRA approved standard. So a working group was established. Sheesh! What an experience.

Since its founding just over 12 months ago the group has been a shambles to say the least. One group, form the UK with some USA participation, has gone off to develop things their own way. Others have been unhappy with the behaviour of some members. Now one participant with a very clear idea of what is needed (his proposal) has managed to get the Chairman sacked and he has been appointed in his place! Two weeks ago the working group had I think 18 members. Yesterday, after my departure it had ten and of those only three or four have made any contribution at all to the discussion and it seems that two of those are not happy with what is happening either!

So the group is going well and moving forward by all accounts of the new chairman. I suppose he has nobody left to argue with him and he seems to have perfected the "management of the standards process by attrition". Oh well, back to the grindstone. After twelve months of sniping, back biting, and a lot of ill feeling we can now get back to work!

Our little group seems to be re-forming. We are talking comfortably about where we see something going and about the uses of modern technology. A far cry from what we had been putting up with for the last year.

Atmel Xmega - they just keep on doing it.

2008-04-17T11:02:00.000-04:00

Over the last year or two Atmel have updated their AVR line with a 32bit machine (AVR32), new small processors with lots more features, picoPower technology to keep things cool, and now - ATXmega.

Take an ATmega, add multiple DMA channels, an event handler system, four SPI ports, four TWI ports and EIGHT USARTs in a 100 pin chip! Talk about packing it in! Oh, did I tell you that without losing ANY of the specialist ports, it can also access up to 16mb of RAM, and has an SDRAM controller built in?

Things have come a long way since the AT90S8515!

Look at Atmel or AVRfreaks for more information

Is it really that long?

2008-04-17T11:00:00.000-04:00

I just looked at the last entry here and find it was nearly five months ago! How time flies when you are having fun!

Does a new job, a week in hospital, seemingly endless trips to the cardiologist and a long winter sound like fun? Well it hasn't been too bad, really! But now I am back. And maybe we can have some electronics fun.

The NIOS-II goes ASIC - Processors migrate

2007-11-28T10:03:00.000-05:00

With Altera and Synopsys recently joining forces to offer the NIOS-II processor core for use in ASIC's, and the attendant media focus, it is worth looking around at what others have been doing as well.

ARM has a number of chip makers using the ARM-7 and ARM-9 cores in a variety of products, as well as it being available in FPGA's. MIPS has its cores in MCU's form Microchip now, as well as in ASICs.

So when are we going to see a NIOS-II based MCU? We can already put a NIOS-II and a handful of useful peripheral cores into a $15 FPGA (with some external memory) so surely Altera and a chip-maker can come up with a nice low cost package that would enable us to take basically the same processor core from a $6 MCU to a variety of FPGA's and finally into ASICs.

Wouldn't that be nice!

Is assembler really dead?

2007-09-25T15:39:00.000-04:00

I was working away on some NIOS-II component designs today and thought a couple of lines of assembly code would answer a question. So I went looking for the assembler! Darned if I oculd find it! Is assembly language really dead?

SchmartBoards in use

2007-09-25T15:21:00.001-04:00

Okay, so I have been busy, and I haven't been writing here have I. But I have been writing in other places, specifically at SchmartBlog. One issue I addressed there is the matter of bypassing supplies on the SchmartBoard, although you don't find out how coll the arrangement is until you actually use the board! Go have a look here and see what I mean.

Schmart prototyping

2007-07-23T13:58:00.000-04:00

Prototyping is one of those things we need to do but recently SchmartBoard has made it a little easier. Over many years I have used a variety of commercial systems as well as specialised boards I designed for myself. But nobody really has a system quite like the SchmartBoard.

A SchmartBoard is exactly 2 inches (50.8mm) square and it has a specialised pattern on it which allows you to hand solder integrated circuits with pad or pin pitches as small as 0.4mm. I haven't used the 0.4mm yet, but I can tell you that 0.5mm and 0.65mm are a soda to handle, including the 0.5mm QFN style pattern seen here.

This board is a little unusual in that it has two patterns on it, one a 32pin, which can be used for things like the CP2102/3 USB devices, or an Atmel AVR processor, while the 10 pin one can be used for a variety of power devices and driver devices from manufacturers such as Maxim. I tried all manner of techniques for hand soldering QFN's, but this is the only one that works.

So how do they do it?
The SchmartBoard actually has a shallow groove where the IC pin sits. And that is the secret! My method is a little different to that in the documentation, before I mount the device I use a solder flux pen (felt tipped), my favourite being the Kester #2331-ZX which I usually buy from DigiKey, and applying a small amount of flux along the board where the pins will sit. I carefully place the IC using tweezers (a magnifier does help!) and while holding the device down with the tweezer points I carefully tack solder two diagonally located pins on the device.

Then I carefully check alignment and solder the remaining pins, usually using an STTC-106 tip in my Metcal MX-500 solder station. Of course you don't REALLY have to have a $600 station like a Metcal. Your good old fashioned Weller or whatever will work with a VERY fine tip of appropriate temperature.

After soldering the device I clean up any excess flux with an MG Chemicals Flux Remover Pen 4140-P, again from DigiKey.

Pullup resistors - how and why

2007-07-05T07:57:00.000-04:00

I was working away yesterday when I got an IM from a hobbyist friend

"I was playing with some switches and your design said to use 10K pull-up resistors, they take about 500uA of current each, why so much? Aren't pull-ups just to get a voltage?"

Well, yes and no! There are several reasons to use a pull-up resistor

Establish a logical 1 input on the pin.
Provide wiping current for switches.
Act as a current source for something like an open-drain or open-collector output

Back in the dark ages when TTL (Transistor-Transistor Logic) ruled, logic inputs actually drew current! Not a lot, but to ensure that a pin was pulled 'high' you needed to source at least 40uA at a minimum of 2.4V. The input of a TTL circuit is typically the open emitter of an NPN transistor. So generally a value between 1K and 5K was commonly used. Todays most common integrated circuits use CMOS technology, and if the pull-up is merely to provide a logical 1 at the input then even 100K would be acceptable. Many microcontrollers such as the Atmel AVR and Microchip PIC parts have internally selectable pull-ups for convenience and reduced parts count. The actual resistance value will vary, but is often in the range of 40-80K ohms.

Switches open up a whole new ball game. The contacts of most switches are made with a highly conductive metal plating over a lower cost metal such as brass. When selecting a switch for your application check the data carefully as some types will require a minimum 'wiping' current which is needed to inhibit oxidation of the contact surface, particularly for designs where the switch contacts do not 'wipe' across each other. Once again, modern parts require lower currents, but if a switch seems to be unreliable, try increasing the current by reducing the value of the pull-up resistor.

When the resistor is used to provide the output load for an open drain or open collector circuit its value needs to be high enough to keep the current down to a reasonable value, but low enough to provide enough current to get the required speed. A perfect example is the I2C (i-squared-c) bus from NXP. A large number of inputs can appear in parallel so the pull-up needs to provide sufficient current to take all of them to the high state. And it must do so whilst charging up the input capacitance of all the devices and any parasitic capacitances in boards or cables quickly enough to get the appropriate rise times.

One common mistake I see is people using I2C with controllers and accepting the internal pull-up as being adequate for driving the bus. It just might work if the one I2C peripheral or memory part is the only thing connected to the processor and it is very close to the host. But even then many users report that they cannot get the 100kHz or 400kHz speed of the I2C bus, the might have to reduce the clock to 10kHz or even less. I2C was specified with a 4.7K pull-up for a darned good reason, and you will see that the rise times and thus speed capability of the bus only achieve optimal values when you use that pull-up.

Responding ... to the user - an LED dimmer

2007-07-04T07:37:00.000-04:00

It seems that the one thing setting small design houses, such as mine, apart from the big boys, is the money we can spend on the 'user interface' to our hardware such as my recent LED dimmer project. Every day we look longingly at the nice membrane keypads, joystick actuators and the current crop of easy to use silicone keypads like those on your TV remote. So how on earth can we do those sorts of things without spending horrendous amounts of money?

Recently I was looking at a small joystick device that was emulating a mouse on a board, very nice. When I tracked it down it turned out that there are a couple of new things out there to make our lives easier.
First came the ITT TPC1133 'tri-directional' navigation device. Or as it has become known in this office, the jogger. Push the small arc segment one direction, it closes a pair of contacts, push it the other way and it closes the other pair. Now when you leave it centred and push in, it closes both pairs. Very nice.

So where to get it? Well having tracked down the part at ITT Industries I then started looking at distributors, surely nobody would stock such a useful thing? At the first port of call I was right! Turns out Mouser must have stocked it for a heartbeat, but now they tell us it is obsolete! Darn, so search on. Saved, once again, by our good friends at DigiKey. Who not only list it, but have stock, and at very reasonable prices.

Now I had the solution to a problem, I needed to control the brightness of some LEDs very simply. Using this little jogger I was able to produce a board all of 19x50mm ( 3/4" x 2" ) that uses PWM to dim the LEDs, and here is how it turned out.

The jogger is tiny, suits this application perfectly and has been well received already by users. So much so that it is spawning an entire range of related products. Thank you ITT and DigiKey.

How did it come to this?

2007-07-04T07:27:00.000-04:00

It seems now that this decision to start my first blog is long overdue. For many years I have kept detailed lab notebooks of my work and every now and again something in there is useful to somebody else. Over the last few years people have been saying "why not blog it?". Well, why not.
What you will see here has no grand plan. I hope it will be a collection of interesting, thought provoking, and sometimes even useful snippets based on things that I am working on.