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Embedded Muse 211 Copyright 2011 TGG August 15, 2011

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EDITOR: Jack Ganssle, jack@ganssle.com

Editor's Notes

Are you happy with your bug rates? If not, what are you doing about it? Are you asked to do more with less? Deliver faster, with more features? What action are you taking to achieve those goals?

In fact it IS possible to accurately schedule a project, meet the deadline, and drastically reduce bugs. Learn how at my Better Firmware Faster class, presented at your facility. See https://www.ganssle.com/onsite.htm .

New! I'll be conducting public versions of this class in Chicago on October 21 and in London on October 28. More info here: https://www.ganssle.com/classes.htm .

I'm not fond of podcasts and the like. It's far faster to read text than to listen to an audio recording or a video presentation. But they sure are fun to create. Recently I had a great conversation with Chris and Dave on The Amp Hour, which was broadcast here. We talked about the future of embedded engineering, the importance of vacation, and much more.

Quotes and Thoughts

The only thing that should be reused from some projects is the hard
disk space. Charles Manning

Tools and Tips

The tool tips keep pouring in! Keep `em coming.

Except for this week!

Contest!

Microchip has generously donated three chipKIT Max32 Arduino-Compatible Prototyping Platforms (see http://www.digilentinc.com/Products/Catalog.cfm?NavPath=2,892&Cat=18) for a contest.

So here's the deal: send in a computer-related joke that has not been used in the Muse. The "best" three will win. To make it harder, the only database of Muse jokes is tediously-stored in the back issues (https://www.ganssle.com/tem-back.htm).

Our highly trained joke selection staff has been studying all summer in preparation for the contest. Eye rolls for silly entries has left us squinty and mean. We're hoarse from chuckle practice and left hard of hearing from the two-week loud guffaw class. ROFL 101 put one of us in traction.

The contest closes August 26, so we'll announce the winners in the next issue of the Muse. They will be selected using precise measurements of funny bone vibratory patterns using a spectrum analyzer coupled to the usual bank of harmonic humdinger heterodyners, detected by a jocularity diode.

Send your entries to marybeth@ganssle.com Sorry, we can't acknowledge entries. I'll post the winners' names (but no other contact info) in the next Muse and any funny or interesting commentary.

The Dumbest Thing I Did

When interviewing I always ask candidates (those with experience) about their dumbest mistake and what they learned from it. Those with no mistakes are generally those with no experience - or are perhaps truthiness-challenged. Do you have any?

Christian Schultz confessed to this: "I was thinking about one of the dumbest thing I did. It was in the beginning of the 90's, I was working in my first project for my first client. It was a board with a microcontroller and some logic gates. I had to show him something working in the next day. I worked all night in the circui, in a premade bare board, full of wire wraps. When it worked fine, it was about 6 am. I got my car and headed to my client company, 600 kilometers (370 miles) away from my town (plus the fact that Brazil doesn't have the best roads of the world). When I reach there, and turned the circuit on, it showed a completely crazy behavior. I simply can't explain in words my face expression. After more 600km till home, I finally realized that my circuit didn't have any capacitor in the power lines. A single ceramic capacitor did the job. Since that day, I became a capacitor-addicted in my circuits...

"That was one the dumbest thing I did, the dumbest is hard to choose, if it's about my marriage or choosing my career."

James Thayer fessed up to: "It's not the dumbest thing that I ever did, but reading through others tales of woe reminded me of the time that I discovered that it was possible to change the function of any key on the keyboard of the Apollo workstation that I was using.

"Being an engineer, it occurred to me to wonder whether it was possible to change the function of the Return key. So, I typed in the appropriate incantation which, of course, was terminated by hitting the Return key. I was delighted to find that, indeed, the Return key now behaved according to its new function. My curiosity satisfied, I typed in the appropriate incantation to restore the Return key to its original function. It was at the moment that I hit the Return key to terminate the command that I realized that I had a bit of a problem..."

NRE

Some years ago I visited Agilent's oscilloscope division in Colorado Springs. They had just finished designing the "Infinium" series of scopes. The product was - and is - impressive. Still more interesting was their development approach.

The engineers told me that every time they started work on a new product they'd first design the device's computer board. But, Agilent is not a computer company. Why, they wondered, focus on endlessly creating embedded computers instead of zeroing in on the product's application?

This minor revelation shaped the Infinium's entire development strategy. Instead of an embedded computer the scope uses an off-the-shelf PC motherboard.

Revelation number two: why spend so much time and effort getting a cranky embedded RTOS and complete environment going? The Infinium runs Windows, starting the scope app once the OS boots.

These two decisions cut man-years from the development process. Designers immediately jumped into the meat of the product, building hardware to suck in analog data at astounding rates, and writing code to display and interpret this data.

Recently I looked at their new MSO-X-3XXX series of scopes. These, too, run Windows.

I imagine Agilent sells thousands of these scopes each year. Not millions - it's not a high volume product like a cell phone. The average price is many thousands of dollars, so there's room to increase costs - some - to shorten development time. That PC motherboard is surely not the cheapest solution, but cutting man-years of effort saves money over the product's entire lifecycle.

In my job as embedded gadfly I look into the workings of an awful lot of companies building products. A phenomenal number never balance the NRE (non-recurring engineering) versus cost of goods equation. The math is simple: if it costs X dollars to develop a product, and Y units are sold, then the engineering cost per unit is X/Y. It's a cost that is as real as the price of the chips and resistors, the RTOS licensing fees and the plastic enclosure.

NRE is a cost that must be amortized over the product's lifecycle. To do otherwise means one cannot make intelligent engineering tradeoffs. Spend half a mil on an ASIC and, if volumes are low, the per-unit cost of that chip is thousands of dollars. Does this make sense for your product? Add these thousands to the production cost of the product - is it still profitable? If not, you're going broke.

(Of course, there are cases where other factors intrude - size, power, and the like may overwhelm simple cost drivers).

Maybe you really do need to design that 8051-based board, but sometimes it's far cheaper, in the long run, to use a more expensive solution like a Basic Stamp, or an Atmel or Microchip evaluation board. In low volumes I betcha you can't beat what initially might seem like the high prices of these done, tested, working-today solutions.

To design, debug, respin, retest, document and productize a not-terribly complex PCB will cost at least $25k. $100k is not out of the question.

If size, power and other factors aren't a huge issue, and if volumes are low, how can a responsible designer not pick a COTS solution?

Jobs!

Let me know if you're hiring firmware or embedded designers. No recruiters please, and I reserve the right to edit ads to fit the format and intents of this newsletter. Please keep it to 100 words.

Joke for the Week

Note: These jokes are archived at www.ganssle.com/jokes.htm.

Here's an old one that has been sitting in my files for years - so long, these OSes are largely obsolete!

If Operating Systems Were Beers...

DOS Beer: Requires you to use your own can opener, and requires you to read the directions carefully before opening the can. Originally only came in an 8-oz. can, but now comes in a 16-oz. can. However, the can is divided into 8 compartments of 2 oz. each, which have to be accessed separately. Soon to be discontinued, although a lot of people are going to keep drinking it after it's no longer available.

Mac Beer: At first, came only a 16-oz. can, but now comes in a 32-oz. can. Considered by many to be a "light" beer. All the cans look identical. When you take one from the fridge, it opens itself. The ingredients list is not on the can. If you call to ask about the ingredients, you are told that "you don't need to know." A notice on the side reminds you to drag your empties to the trashcan.

Windows 3.1 Beer: The world's most popular. Comes in a 16-oz. can that looks a lot like Mac Beer's. Requires that you already own a DOS Beer. Claims that it allows you to drink several DOS Beers simultaneously, but in reality you can only drink a few of them, very slowly, especially slowly if you are drinking the Windows Beer at the same time. Sometimes, for apparently no reason, a can of Windows Beer will explode when you open it.

OS/2 Beer: Comes in a 32-oz can. Does allow you to drink several DOS Beers simultaneously. Allows you to drink Windows 3.1 Beer simultaneously too, but somewhat slower. Advertises that its cans won't explode when you open them, even if you shake them up. You never really see anyone drinking OS/2 Beer, but the manufacturer (International Beer Manufacturing) claims that 9 million six-packs have been sold.

Windows 95 Beer: You can't buy it yet, but a lot of people have taste-tested it and claim it's wonderful. The can looks a lot like Mac Beer's can, but tastes more like Windows 3.1 Beer. It comes in 32-oz. cans, but when you look inside, the cans only have 16 oz. of beer in them. Most people will probably keep drinking Windows 3.1 Beer until their friends try Windows 95 Beer and say they like it. The ingredients list, when you look at the small print, has some of the same ingredients that come in DOS beer, even though the manufacturer claims that this is an entirely new brew.

Windows NT Beer: Comes in 32-oz. cans, but you can only buy it by the truckload. This causes most people to have to go out and buy bigger refrigerators. The can looks just like Windows 3.1 Beer's, but the company promises to change the can to look just like Windows 95 Beer's - after Windows 95 beer starts shipping. Touted as an "industrial strength" beer, and suggested only for use in bars.

Unix Beer: Comes in several different brands, in cans ranging from 8 oz. to 64 oz. Drinkers of Unix Beer display fierce brand loyalty, even though they claim that all the different brands taste almost identical. Sometimes the pop-tops break off when you try to open them, so you have to have your own can opener around for those occasions, in which case you either need a complete set of instructions, or a friend who has been drinking Unix Beer for several years.

AmigaDOS Beer: The company has gone out of business, but their recipe has been picked up by some weird German company, so now this beer will be an import. This beer never really sold very well because the original manufacturer didn't understand marketing. Like Unix Beer, AmigaDOS Beer fans are an extremely loyal and loud group. It originally came in a 16-oz. can, but now comes in 32-oz. cans too. When this can was originally introduced, it appeared flashy and colorful, but the design hasn't changed much over the years, so it appears dated now. Critics of this beer claim that it is only meant for watching TV anyway.

VMS Beer: Requires minimal user interaction, except for popping the top and sipping. However cans have been known on occasion to explode, or contain extremely un-beer-like contents.

About The Embedded Muse

The Embedded Muse is a newsletter sent via email by Jack Ganssle. Send complaints, comments, and contributions to me at jack@ganssle.com.

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