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Issue Number 371, April 1, 2019
Copyright 2019 The Ganssle Group

Editor: Jack Ganssle, jack@ganssle.com

   Jack Ganssle, Editor of The Embedded Muse

You may redistribute this newsletter for non-commercial purposes. For commercial use contact jack@ganssle.com. To subscribe or unsubscribe go here or drop Jack an email.

Editor's Notes

Express Logic

Over 400 companies and more than 7000 engineers have benefited from my Better Firmware Faster seminar held on-site, at their companies. Want to crank up your productivity and decrease shipped bugs? Spend a day with me learning how to debug your development processes.

Attendees have blogged about the seminar, for example, here, here and here.

Jack's latest blog: On Expert Witness Work.

Quotes and Thoughts

"The weaker the data available upon which to base one's conclusion, the greater the precision which should be quoted in order to give the data authenticity." Norman Augustine's 35th law.

Tools and Tips

SEGGER Embedded Studio The leading cross platform IDE

Please submit clever ideas or thoughts about tools, techniques and resources you love or hate. Here are the tool reviews submitted in the past.

In the last Muse I noted that we might not apply a very rigorous failure analysis to an appliance like a toaster. Chuck Petras had hard data:

Actually there are safety standards for that toaster. Its not quite DO-178, but its trending that way.

Guidelines for obtaining IEC 60335  Class B certification for any STM32 application here.

APIEC60730: IEC 60730 Safety Standard for Household Appliances here, here and here.

Safety Concerns for Smart-Enabled Appliances here.

A lot of readers corresponded about the two recent 737 MAX crashes. There's still much we don't know, and all of us will be very interested to see how this plays out. Bob Landman sent an excellent link about the MCAS system. On modern aircraft some of the automation is for "envelope protection" - preventing the pilot from doing something unsafe. Perhaps the most extreme form of this was, according to David Mindell's Digital Apollo, on the first manned spaceflight. Yuri Gagarin was blocked from the controls by a padlock whose combination was in a sealed envelope! Aviation enthusiasts joke that in the future the cockpit will be occupied by a pilot and a dog. The pilot is there to reassure passengers that the flight is safe; the dog's role is to bite the pilot should he/she touch the controls.

Freebies and Discounts

Thanks to the fine folks at Cmicrotek, this month's giveaway is (your choice) either a µCP100 or µCP120 current probe. These are instruments that measure the current consumption of low-power IoT-type systems. I reviewed them here.

Cmicrotek uCP100

Enter via this link.

April 1: The Perfect UI

As one gets older short-term memory tends to degrade. We joke about going into a room to do something and then having no idea what that was when we get there. Or forget to turn off the BBQ gas. Not checking the laundry.

As an engineer I wanted to invent a solution. Perhaps one could take the traditional route and tie a string around one's finger. But I'm sure we'd forget what the string was for. Heck, there's probably a digital string around that squeezes your finger to get your attention.

So we came up with a technical solution. We decided to get a kitchen timer to beep us into lucidity. Need to get the clothes from the dryer in 45 minutes? Crank that into the timer. Have to turn off the sprinkler in a half hour? Set the reminder timer.

At the store we found a huge assortment of choices. Mostly electronic, they sport nifty LCD displays and a variety of buttons. Some have programmable ring tones. Others will vibrate. After careful consideration of user interface issues we settled on an old-fashioned mechanical timer.

You'd think a knob-happy test equipment junkie would select the latest electronical wizardry. But those versions all take some manipulation to use. You have to either type in a number of digits, or press and hold different buttons to set the time. Or you could set your cell phone clock. But all of these approaches are slow, cumbersome, and a pain to use.

The mechanical version is an example of perfection in UIs. Just crank one knob to the desired time and wander off. What could be simpler, easier or faster (barring some mind-reading technology)? And the thing is loud enough to jolt even ears diminished by decades of power tool use.

Perhaps Nest will come out with a digital version of excruciating beauty that is just as easy to use, with an Internet connection so you can set it while texting at 60 MPH. That would probably only cost $249. In the meantime our $10 mechanical marvel comes to the rescue of failing memories.

As I was typing this Marybeth leapt up exclaiming "the cleaning chemicals in the bathroom! I left them on the tiles too long!"

She forgot to set the reminder timer. Not sure how we're going to remember to use the remembering device.

April 1: Longing

In my 20s I volunteered on a suicide hotline. Some of the calls were heart-wrenching. Occasionally we had to get the police involved.

Then there were those who were miserably alone. Two of us manned the pair of phone lines, and it wasn't uncommon for a lachrymose male caller to be desperately pouring out his heart about his wish for a girlfriend on one line, and on the other a reversal of the sexes. We wished we could, ethically, twist the two phones earpiece to microphone and be telephonic matchmakers.

Admiring the photo I had to admit to myself that I was also smitten. But "Joe" is a friend, and it's unwise to get in the middle of another's relationship, even though my wife is tolerant of occasional lapses of this sort.

Finally I told him: "Go ahead and write a check for that MSO5 oscilloscope. Don't holdoff any longer." With a 15.6" screen and 6.25 GS/s acq rate, how troubled could their lives be? "Just keep communicating," I advised, "via the LAN connection. Any glitch in your relationship will be captured at 200 ps/div, and those troublesome runts will trigger right on the threshold. Coupling is the human condition, and your beloved does AC and DC. Don't crosstalk when changing channels. And if you get the jitters, well, they're only 5 ps."

(This is a mostly-true story from just a couple of weeks ago!)

April 1: The Fox and the Valley

The blue light of the TV flickered on the blank wall, but it went unnoticed by me as I slumped in my old armchair.

It had been a bad week. She left on Monday, screaming that she couldn't take all of the equipment piled everywhere. Me, I thought that old Tek 545 was a collector's item, an antique. Sure, the dust was pretty bad, but you can bet we were the only couple in town with a living room populated by old scopes and CP/M machines.

Women - I'll never understand them. Like, that time my homebrew furnace controller burped and drove the house to 115 degrees when we were gone for the weekend. Hey, I never liked those pets anyway, and the smell did eventually come out of the carpets. Pretty much. I mean, it was just a little software bug; we all have those!

And she never forgave me for the fire. Yeah, next time I'll put a bigger heat sink on the power supply. I admit it - I learned a lesson. The scorch marks on her dresses don't really look all that bad. Jeez, you'd think she'd be a bit more understanding!

I reached for another bag of chips as the chair groaned a bit more. One of these days I'm gonna have to work off some of the excess pounds. A decade spent in the lab drinking Jolt and munching fries had taken its toll. Despite the flab I still know calculus and can program in C; surely a dream dude for any discerning woman. I bet I could wow them at the local watering hole with my great stories about TCP/IP!

Well, this is Silicon Valley after all, where relationships, jobs and careers are measured in milliseconds and loyalty doled out by the microgram. Electronics is a dog-eat-dog business and I'm an old hand at crawling out from the wreckage. Like that last startup I worked for. I told 'em we'd get that product out the door, eventually anyway. We woulda survived if that idiot president just got another couple of mil of venture capital. For a while at least.

Ya know, maybe it was losing that job that ticked her off. I figure, what's the big deal? She should be used to this by now. Check out my resume - it shows lots of experience at lots of places. No one can beat this!

I picked up the phone but heard only the accusing silence of a non-payment disconnection. No matter. Time to find another company looking for my embedded expertise. There's a startup a minute here, pigeons ripe for picking.

I clumped out of the trailer's front door and found Big Al, the usual wild look in his eyes, mouth working hard on this morning's sugar raised, the white powder spotting his beard. "Al, buddy, you're outa work too, huh? How's the wife and kids?"

"Kids? Kids? Yeah, come to think of it I did notice some little people living with me. I wonder where they came from? Check this out." With that he shoved a coffee-stained fragment of the San Jose Mercury News into my hands. I quickly took in the circled want ad. "ENGINEERs - microprocessor savvy designers and programmers needed. C, FPGAs, PLDs, assembly a plus. Exciting opportunity for a motivated developers in a new high-growth company."

A slow smile spread across my face. Here was our pigeon; I was already mentally spending the signing bonus.

That afternoon, T-shirts cleaned and pressed, with most of the donut detritus hurriedly wiped from Al's beard, we met with the president of Galaxar Enterprises. Yep, just as usual, this man was the typical harried executive desperate for people, so desperate he had neither the time nor resources to do much of a background check. Not that my background is so terrible; it's just that there's so much of it.

"You know C? Schematic capture? What's the last project you worked on?" he mumbled, looking at his watch while the beeper pinged an urgent tune.

"We did that Internet Cappuccino maker for Kitchen Services; you must have read about it in the press. Yep, that puppy had a MIPs based coffee engine with 64 megs of RAM!"

"Didn't they go Chapter 7?", he interrupted, interested now.

"Trust me on this. The boss was an idiot. He just didn't understand how much compute power we needed to blend the perfect cuppa joe. That sucker could crank some coffee, believe me. If they hadn't been so stuck on the cost of goods we coulda cleaned up the Cappuccino market. We were practically done with development when the SEC raided us."

"OK, OK, look, when can you start? Now? Don't you guys ever shave? Hell, just sit here and Bob will tell you what to do."

Bob, engineering VP, was one of those snotty-nosed brats with a degree and an attitude. "We're building a new marine VHF radio for the recreational boating market. That means there are three main design parameters. First, the unit must be totally sealed to ensure it's waterproof. Second, the sell price can't exceed $250. And obviously the unit must be simple enough that even the most casual boater can use it."

He went on to tell us how we were going to design the product. Us! Can you imagine? As if I don't understand project planning, structured design, discipline design, and all of that utter crap. Me, I prefer to skip all of that non-productive nonsense and just bang it out.

I zoned out, the drone of Bob's voice barely noticeable, nodding at the right time while planning my next move. Clearly it was time for the old end-run. Saturday night Al and I marched into the president's office. "Herb," I started, "we know you're running out of venture money and an IPO is at least a year away. Bob's planning to spend another three months just doing preliminary design. Whatdoya want, a design or a product? Trust me on this - we can pound out a design in a week, max, and then get the radio done in no time."

Herb's eyes gleamed. It seems that he, too, was frustrated by Bob's methodical approach to engineering. This valley is the land of Steve Jobs, where unbridled passion and hope fuels the dream of tomorrow's big score. Discipline? Bah. Just lemme at a problem and I'll get it done. With a bit more prodding Herb agreed that this project was so important he'd give it skunk-works treatment, get Bob off of our backs, and let us report directly to his president's office.

The week sped by like a read from cache memory. Al slouched into my cubicle, let out a long, satisfying-sounding belch, and asked "didn't we promise Herb a spec or something?" Right! Never let the boss, down, that's my motto. Unless there's a good reason, of course.

"Sure, look, just grab those header files we've been working on and edit a bit of descriptive stuff at the beginning. They'll never read it all anyway. If he complains we'll tell 'em not only is the spec done, we've incorporated it into the firmware. How can he get upset if he sees we're already coding?"

Herb swallowed our header files hook, line and sinker. He's thrilled that we're already cranking out software, and giddily reported our progress to the venture capitalists. I think they're already mentally spending their IPO profits. Bob is muttering vague threats, but he's been squeezed into the user-interface group. He wants Al and I to take on that new college grad, Marty. We're supposed to show him how to get projects done. It's not all bad; the kid has a car so can get us beers and carry-out.

The secret to success in this business is to look busy, keep a prototype in a state that looks like it has some level of functionality, and always agree with the boss. And you can't act like you have a personal life when battling a schedule! Heck, after just three days on the job Marty asked if he could leave at 5 to celebrate his first anniversary. I straightened him out. "Kid, trust me on this. We all go through one or two starter marriages, you know, no kids, no property, no regrets. Don't take it too seriously. Now let's order a pizza and get back to work." It was probably a good thing that I turned off the switchboard that night, so he wouldn't get distracted by all of those frantic calls from home.

And that kid did need some attention. I caught him late one night doing a spell check on his comments! Somehow he missed the fact that a ship date loomed; comments are always the first thing to go. "Kid, trust me on this. Never include a comment that will help someone else understand your code. If they understand it, they don't need you." I think he gets the picture now.

As time moved on we started having trouble fitting the binary image into the CPU's 64k address space. "This always happens", I reassured Herb, "them 8 bitters just can't handle the sort of code we're cranking out for you. Look, we'll just stuff a bigger part in there this afternoon. No problemo; I've done this a million times."

Big Al's eyes lit up when I suggested we look into a 32 bit processor. "I've got just the ticket. There's one I've been itching to try; it's totally reconfigurable, you can even define your own instruction set. Man, this is gonna look great on my resume!"

Ah, resume fodder, the grease of the industry. Herb didn't seem to concerned about the increased cost of goods - at least he wasn't asking any questions - so I set out trying to find some way to cool the sucker. With luck a big old heat sink and decent-sized fan might be adequate. Jeez, maybe I'll use the next size up; those burnt dresses still haunt me at times.

We optimized the instruction set on the CPU to play DoomStar III at awesome speeds. The best part of using a custom architecture was that I got to port the entire GNU toolchain to our chip. That compiler sure is tricky! First time I'd ever fiddled with a code generator, so it naturally took a bit longer than planned to get working - mostly - tools.

As the weeks passed Herb got noticeably more antsy, checking on our progress on a daily, and then hourly, basis. This always happens, and is a sign that the old cash reserve is evaporating. I started running to the bank the minute paychecks came out. No one's gonna stick me with bouncing paper! Been there, done that.

Bob - remember Bob? - strolled into the lab one afternoon to check on our progress. It seems the fool had actually invested his own money into the company! He's correspondingly annoying about what we do, even though my end-run had gotten him off the project months before. Oddly, he seemed upset about the cooling fan. "This thing has got to be totally sealed, so no water gets in!" he whined.

"Yeah, yeah, just mount it in a dry place or something", I replied. "I can't be bothered with that sort of stuff. You know how much power this sucker uses?" These company men are all stress puppies. Not me; I'll be going strong when he suffers his first mid-30s myocardial infarction.

Christmas rolled around - or was it Easter? I dunno, we were plenty busy chasing down bugs and making feature changes. Bob's paycheck bounced. I knew that Herb had been doing some fancy footwork to keep things afloat, but when everyone in accounting quit, complaining about insolvency or something, the standard exodus began. As usual, engineering remained untouched by the various rounds of layoffs. They needed the products we make to survive. I love this field!

This seemed like a great time for a two week vacation, though Marty seemed almost hysterical that I'd take off now. "Kid, trust me on this. Never complete a project on time. If you do, they will think it was easy and anyone can do it and they don't need you. Now I'm outa here for a while. Look busy and we'll sort it all out when I get back."

I got back, more or less sober but feeling great, to find the front door padlocked and a sheriff standing guard. Marty, skulking in a dark corner, grabbed my arm and moaned that he couldn't build the code at all while I was away. It seems he had trouble locating all of the source.

"Kid, trust me on this. Never archive all the sources necessary to build a binary. Always hide a few on your own disk. If they can build your binary, they don't need you. What do they teach you in college, anyway?"

He said the creditors got fed up and were demanding their money. Half the employees were suing because their paychecks bounced. A satisfied grin spread across my face as I recalled beating the rest of those idiots to the bank.

Marty shrieked that Herb was suing all of us in engineering for not meeting promised dates, specs, or features. "Kid, trust me on this. They always sue. That's why I own nothing. What do they think they'll get, my trailer? The bank owns that!"

Well, it seems my two week holiday might extend itself a bit. No worries there! After such a tough project I needed a break. It's time to sleep in for a while, build up those reserves.

Days later an awful booming interrupted my sleep. "My god, it's not even noon!" I shouted, "go away". The door slammed open and Big Al loomed over me. "Check this out." He unwrapped the newspaper from around his BLT and handed me a section from the want ads. Yep, old Al was right on top of things again. Another startup, as usual desperate for a pair of gurus like us, no doubt willing to hire at any price.

A harried president briefly interviewed the two of us, asking lots of questions about our most recent experience. We gave him the scoop on the VHF radio, but had to parry his request for references. "Sorry - they went out of business. Shame, that. There's no one there you can call. But we built a hell of a radio for those guys. It's too bad management was so screwed up they folded. Hey, it happens all the time in this industry."

"But trust me on this - you need a graybeard like me to mentor your young engineers, and to get this project out now! I'm ready to start coding today. What is it we're building?"

April 1: This Week's Cool Product

For a number of years now, work has been proceeding to bring perfection to the crudely conceived idea of a machine that would not only supply inverse reactive current for use in unilateral phase detractors, but would also be capable of automatically synchronizing cardinal grammeters. Such a machine is the "turbo-encabulator." Basically, the only new principle involved is that instead of power being generated by the relative motion of conductors and fluxes, it is produced by the medial interaction of magneto-reluctance and capacitive directance. The complete story is here.

Note: This section is about something I personally find cool, interesting or important and want to pass along to readers. It is not influenced by vendors.


Let me know if you’re hiring embedded engineers. No recruiters please, and I reserve the right to edit ads to fit the format and intent of this newsletter. Please keep it to 100 words. There is no charge for a job ad.

Funny job ad

Joke For The Week

Note: These jokes are archived here.

These are the lyrics to The Gates, by Da Vinci's Notebook. The song is fun and worth a listen.

Workin' on a laptop, close to the end
Of a job I've been doin' since half past ten
I don't believe that it's frozen again
The system has gone down-o, down-o, down-o
I don't believe that it's frozen again, the system has gone down-o

So I took it down to the help desk guy
I said, "Make it better, or I'm gonna cry"
He said, "I'm sorry, your computer has died
The data can no longer be found-o, found-o, found-o"
He said, "I'm sorry, your computer has died, the data can no longer be found-o"

To the roof with the laptop I did go
Over to the edge and I gave it a throw
And when it arrived seven stories below
It really made a mighty fine sound-o, sound-o, sound-o
When it arrived seven stories below, it really made a mighty fine sound-o

Well, that didn't do enough to ease my pain
So I went down to Dulles and I got on a plane
Sayin', "This is all Billy Gates's fault
I'm gonna be trackin' him down-o, down-o, down-o
This is all Billy Gates's fault, I'm gonna be trackin' him down-o"

Touched down in Seattle and got off the plane
Hit Starbucks to get out of the rain
Paid all o' my dough for a thimble o' joe
Full o' foam and the cinnamon brown-o, brown-o, brown-o
All o' my dough for a thimble o' joe full o' foam and the cinnamon brown-o

When the Gates found out about my plan
He packed up a bag, turned tail and ran
Megalo-man took it out on the lam
And hid way underground-o, ground-o, ground-o
Megalo-man took it out on the lam and hid way underground-o

Well, the Gates been a'runnin' ever since that day
Thinks he can hide but he can't get away
When I finally find his little skinny behind
Gonna kick it all over this town-o, town-o, town-o
Finally find his little skinny behind, gonna kick it all over this town

About The Embedded Muse

The Embedded Muse is Jack Ganssle's newsletter. Send complaints, comments, and contributions to me at jack@ganssle.com.

The Embedded Muse is supported by The Ganssle Group, whose mission is to help embedded folks get better products to market faster.