Author Archives: Duane

About Duane

Duane is the Web Marketing Manager for Screaming Circuits, an EMS company based in Canby, Oregon. He blogs regularly on matters ranging from circuit board design and assembly to general industry observations.

Raspberry 6.283185307 Zero

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AKA a second post on the Raspberry Pi Zero.

It’s been two months since the release of the $5 Raspberry Pi Zero, and I still haven’t been able to buy any. As I discussed in my prior blog about it, there is plenty of discussion around the fact that, out of the box, it’s not real useful without adding enough accessories to make it as expensive as any other Pi model. I certainly understand that point, but here’s another way of looking at it.

If you want to learn software, buy one of the other Pi models. If you want to learn about hardware design, buy the Pi Zero and download some CAD software. Then go online and get the Pi Zero dimensions and start designing accessories for it. You can start with one of the many open source Pi Zero accessory designs, or come up with your own. Don’t look at it as a system that’s missing too many parts. Look at it as a base for a different type of learning.

One of the scariest things about designing a plug-in/on board for a bigger computer is the possibility of a mistake that will fry the expensive board. With the Pi Zero, you’re risking $5.

Like I said, I still don’t have one, but I’ve drawn up my for Pi Zero accessory:

It will plug right on to a Zero as a rechargeable Li-Poly power supply. Not at all a complex circuit, but it’s only the first in a series. As a small board, it doesn’t cost much to get fabbed, so for about the price of one PCB sized to fit the bigger Pi boards, I can get two of these.

Next, I’ll design a motor driver, and then possibly an IMU, or sensor board.

Duane Benson
If you have your Pi calculate Pi, would that Pi be Pi enough for Pi?

http://blog.screamingcircuits.com/

Language Dialects for the Engineer Entrepreneur

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Much of marketing can be summed up with the word “communication.” It’s communicating about a product or service, about wants and needs, or the past and the future. Good marketeers take this to heart and work hard to understand their market. But, it’s more than just understanding the market; it’s understanding all aspects of their language.

I often talk about the language, or dialect, that people use. When I do, I’m not talking about English English vs. USA English. I’m talking about the difference between hearing and speaking; or between reading and writing. And I’m talking about that within the same person. Knowing the difference is often the deciding factor between winning or losing this game.

Speaking of games, in baseball, right handed players catch the ball with their left hand and throw with their right. Lefties do the opposite. Except me. Baseball was always difficult for me because I both catch and throw with my right hand. It slows things down considerably when you catch the ball in your right hand, take it out of your glove with the left, drop your mitt, hand the ball back to your right hand, throw it with your right hand, and then pick your mitt up off the ground.

In the same vein, a lot of people speak and listen in different dialects. Like the baseball, information comes in one way, and goes out another. If you don’t plan your communication with that in mind, your conversation may go over about as well as I would as a shortstop in Game Seven of the World Series. The thing is, most people don’t realize that they do this. It’s a perfectly normal, but often not recognized aspect of human communication.

Is it “form over function” or “function over form?”

Case in point, electrical engineers. Material written by a typical engineer is detailed, accurate, comprehensive, and often barely readable by anyone but the author. A common phrase heard in the technical world is that the content is what’s important, not the spelling or grammar. An interesting contradiction is that engineers are often the quickest, harshest, and most pedantic of the “grammar police” that toss flame around in the social media world when someone chooses the wrong member of the set “there, their, or they’re.”

I maintain that both statements — “it’s form over function” and its counterpoint, “it’s function over form” — are incorrect. The correct maxim is: “form can’t get in the way of function.”

Form works with engineers. It works with everybody. Good advertising works with engineers. Where marketeers run into trouble is when they consider form to be too important, and they obscure the message. The reverse, putting too much weight on function, and not enough on form will be just as ineffective.

Engineers getting into marketing, either as an entrepreneur, for their own startup, or as one moving from a technical job into one that requires a lot of writing, need to pay special attention to this phenomena. You can’t write for yourself.

Anyone, not just people in the same technical field, should be able to read good writing. They may not understand all of the technical details, but they should be able to comfortably read and feel a sense of organization. Order, structure, and simplicity are important, regardless of the intended audience. My recommendation is that you have someone, with a lot less knowledge of your subject than you have, read your material. If they can get through it, you’re at least on the right track.

Duane Benson
Do you speak MBA?
Do you speak EE?
Are you an interpreter?

http://blog.screamingcircuits.com/

Predictions for the End of the Decade

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Half a decade ago, back in January 2010, I wrote up a list of predictions for the end of the decade. You can read that list here. It’s still 2015, so I can plausibly say that we’re halfway there, which is a good time for a status update.

0000: In 2010, I said: By the end of the decade, 50% of all passives will be embedded passives and 20% of all PCBs will have 90% or more of their passives embedded.

In 2015, I say: This doesn’t look to be coming true, but it still might. As mobile devices and wearables get smaller, or more powerful, more electronics will need to be stuffed in progressively smaller areas. Those passives need to go somewhere. That somewhere could be into the PCB, or into the chips. I think the PCB is more likely.

0001: In 2010, I said: By the end of the decade, quad stack PoP (package-on -package) will be commonplace.

In 2015, I say: Quite likely. Double layer POP is showing up on low cost devices, like the $5 Raspberry Pi Zero. If it can go there, it can go pretty much anywhere. It won’t be long before double stacking won’t be enough. Although, the layers may end up being inside the chip package, rather than individual chips as layers.

0010: In 2010, I said: By the end of the decade, Each individual human will have their own IP address. Several of us will have more than one. That way, we can jury rig accelerometers into our hands and feet so we can wirelessly know where each of our extremities are at all times. Cats will have them too.

In 2015, I say: Yep, and then some. I already carry one in my pocket. In five years, we’ll likely see personally assigned IP addresses that won’t be device-dependent. We’ll be able to buy IP-enabled clothes, like gloves, which will do a lot more than just know where each finger is. The pet ID chips that today use NFC will be available in wireless Internet connected versions.

0011: In 2010, I said: By the end of the decade, solder paste will be used less often than not when assembling components on to PCBs.

In 2015, I say: We will be seeing welded copper, additive embedded 3D printing processes, conductive glue, and other non-solder methods of assembly, but nowhere near to the degree I was thinking back in 2010.

0100: In 2010, I said: By the end of the decade, nearly all hydraulics and pneumatics in new motor vehicles will have been replaced by electrics.

In 2015, I say: This is already well on the way. With electric and hybrid electric cars growing in numbers, and with weight and fuel mileage being such a concern, this has to happen.

0101: In 2010, I said: By the end of the decade,the first semi-autonomous passenger vehicle will be on display on the auto-show circuit. Hobbyist built semi-autonomous cars will already be on the road.

In 2015, I say: I may have missed the boat on this prediction, in the pessimistic direction. Part of it has already happened. I haven’t yet seen hobby kits, but most of the major car manufacturers have shown models. Tesla has a really good driver assist “auto pilot,” and is promising fully autonomous vehicles for sale within two years of this writing.

0110: I said: By the end of the decade, “airline pilot” will generally be a really, really, really boring job. That’s a bit of a problem.

In 2015, I say: The necessary level of automation required for this prediction to come true is already installed in most airliners. The only real question remaining, is how long before it changes from “Pilot primary, systems secondary” to “Systems primary, pilot secondary.”

0111: In 2010, I said: By the end of the decade, most military “foot action” will consist of two soldiers in command of a squad of robots and those two soldiers will as likely be in Fort Lewis, Washington as in the combat zone.

In 2015, I say: Sadly, I still think this will happen. Not sad that fewer humans will be shooting and getting shot, but sad that we as a species will still consider war important enough to be throwing large quantities of money and resources at.

1000: In 2010, I said: By the end of the decade, the president of the US will be promising health care reform as the highest priority.

In 2015, I say: Yep. The president, presidential hopefuls, senators and representatives will still see this as a hot issue. One side will be trying to make quality healthcare more accessible, the other side less. One side, more publicly funded, the other side, less. I’m not really sure which side will be doing which, but I’m certain that each side will say they want to fix it and the other side wants to destroy it. Ugh.

1001: In 2010, I said: By the end of the decade, routine bioengineering will be, well, routine. Very scary.

In 2015, I say: I’m not so sure about this one. When I wrote it, I was thinking that home bioengineering would be happening and a class of bio-hackers would be emerging. That may still happen, but it won’t be common. Governments, agriculture, and medicine will be doing a lot more of this, but I’m not sure the term “routine” will be accurate.

1010: In 2010, I said: By the end of the decade, the 2019 recession will be looming large and all the people who have forgotten about the 2009 recession and the 2001 recession and the 1985 recession and the 1975 recession … will be freaking out again.

In 2015, I say: Is there any doubt? Does this ever not happen?

1011: In 2010, I said: By the end of the decade, lead will be gone from 98% of new electronics. Bummer.

In 2015, I say: Exemptions are going away. This will happen.

1100: In 2010, I said: By the end of the decade, four of the substances that replaced the substances removed from electronics due to RoHS and similar regulations will have been found to be significantly more harmful to the environment and the people recycling the materials than are the substances that they replaced.

In 2015, I say: I was being tongue-in-cheek, but it still might happen. The only caveat is that if it does happen, the data will be so obscured by politics that it likely won’t be possible for anyone to come to an informed opinion.

1101: In 2010, I said: By the end of the decade, the world of intellectual property will be in even more of a mess than it is today. Virtually everything will be accessibly for easy theft and cheap replication. (This is pretty much a big “duh.”)

In 2015, I say: This is still well on the way. Any industry that designs things will need to adapt to keep competitive. The patent world will still be a mess. Copyrights will be more of a litigation attack weapon than a protection tool. The best defense against pirates will be faster innovation. On the positive side, a lot of IP sharing will be intentional (by the inventor) and many businesses will be built based on collaborative innovation.

1110: In 2010, I said: By the end of the decade,building your own multipurpose robot will be as easy as building your own PC was in 1988. Hardware components and operating systems will be off the shelf, but standards will be pretty loosely defined, interoperability will be more theory than reality and applications will be sketchy and buggy.

In 2015, I say: This will happen, but it may be a little later than the end of the decade. The technology will very much exist for this to happen, but the capability of the hardware will probably be advancing so fast that even the limited amount of standardization needed for this won’t be possible.

1111: In 2010, I said: By the end of the decade, still no flying cars and personal jet packs, dadgummit!

In 2015, I say: And, still no real hover boards.

Duane Benson
http://blog.screamingcircuits.com/

The Common Parts Library

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The two most common causes of delay in small volume manufacturing here at Screaming Circuits (and presumably, others like us) are component availability, and footprint mismatches.

We don’t substitute parts without your approval for a number of reasons. I’ve written about those reasons a few times before. (Here, here, and here.)

Incorrect footprints can lead to a host of headaches as well. (Read more here, here, and here.)

Until recently, I haven’t seen a lot of progress toward solving these problems for the hordes of engineers that don’t have big support departments at their disposal. In fact, with the proliferation of newer, and small, component packages, and evolution of the supply chain, it’s really gotten worse.

However, there are a couple of Knights in Shining Armor riding in to try and solve both problems. The Common Parts Library (CPL), created by Octopart, aims to create a list of components with the highest probability of being available and staying available (there are no guarantees where component supply is concerned).

The other exciting entrant is SnapEDA. SnapEDA has a massive, and growing, library of component footprints. I’ve used their footprints with good success for high pin-count devices, and other parts with complex packages. It can save a lot of time and give better confidence that all of the pins go to the right functions.

Duane Benson
Map makers put fake roads in as copyright traps
These folks don’t do that. Nice.

http://blog.screamingcircuits.com/

Raspberry Pi — What’s It All Mean?

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What would you do with a computer that costs $5?

First, let me explain a bit. The Raspberry Pi, if you don’t know, is a small, inexpensive single board computer designed by the non-profit Raspberry Pi foundation in England. Its mission is to make computer-related education less expensive and more accessible to the masses. As a next step in that mission, it just introduced the Raspberry Pi Zero, with an MSRP of $5. So, you can buy a Big Mac, or a Pi Zero. You could buy some peanut butter, jelly and a loaf of bread, eat that for the next five lunches, and buy five Pi Zeros.

Now some folks have complained that it’s not very useful on its own. It needs a wall bug power supply, a micro SD card, a few cables, and a USB hub to connect a keyboard and mouse to.

That’s true, if you want to use it as a full PC workstation, which you can. It runs the “Raspian” distribution of Linux. But, I don’t think that’s where the greatest potential for this thing lies. No, I wouldn’t use this as a workstation. It’s biggest potential, in my opinion, is as an inexpensive embedded controller.

It has I2C, SPI, and RS232 pins available, as well as plenty of GPIO. Attach a small daughter card with accelerometer, gyro, magnetometer, and GPS, and you’ve got a nice drone auto pilot. Attach a few sensors and a cell phone module, and you’ve got a remote data logger. What would you do with one of these?

Duane Benson
Little Jack Horner couldn’t get a plum out of this pi.

http://blog.screamingcircuits.com/

An Engineer Entrepreneur’s First Brand Lesson

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If you’re an engineer starting a business, do you need to worry about your business’s brand?

In a word: yes.

You don’t need to make a big project out of it at the start. It can be as simple as a collection of notes. But simple or complex, you really need to start right away. Doing so will make things much easier down the road. The nice thing is that you can get started quite small. You don’t even have to call it a plan. At this point, it can just be a vision. (If the word “vision” seems too buzzwordy, then just call it “a bunch of ideas”)

What is a brand?

A brand has a lot in common with a person’s personality and reputation. It’s close enough that you can think in those terms. And, think, you should. Think about what you would like people (customers, employees, friends, family, etc.) to think and feel when they hear your company’s name.

What personality do you want your company to have?

  • Are you mean and gruff?
  • Are you nice?
  • Quiet?
  • Loud?
  • Helpful?
  • Athletic?
  • Sedentary?
  • Reliable to a fault?
  • Usually reliable?
  • …

Will you strive to be perfect, just okay, or a bit better than “good enough”? Do you want people to see you as having the best technology, or the best price? Go on with questions like that. Write down your questions, and write down your answers. You can carry a small note pad and pen around, but I suggest that you use a memo application on your phone. You’ll always have it with you, and it’s quick and easy to use.

When you walk into a grocery store, look at the signs. Do they strike you as inviting, or cold? When you get new tires for your car, watch how you’re treated. When you order parts online, consider how easy or difficult the web site is to use. Will any of that, or something similar, apply to your business? If so, jot down a quick note about it. Make a note any time you see or think of anything that triggers thoughts of what you want your business to be like.

You’ll collect all of these notes and clean them up a bit. These will become your brand attributes. They are the seed of a brand for your company.

Once you have this seed, you’ll use it to guide business decisions – all of them. For example; if financially frugal is one of your chose attributes, you won’t go out and rent a big office with mahogany paneling. If you want to be seen as leading edge in the media world, you might buy Mac laptops instead of clunky desktop Windows PCs.

Every thing you do and say, all of the time; it is all part of your brand.

A few example notes:

  • Am I cheap or expensive? Neither – I just want people to feel like they got a bit more than their money’s worth.
  • What about flashy? A little, but only where relevant. I don’t want fancy boxes, but I want them to look befitting of new technology.
  • I’m selling to engineers in banks, so casual suits if I’m in the front office, but no suits when I’m not.
  • Do I want people to envy my lifestyle? No, I want them to see me as a crazy workaholic.
  • What about getting in touch with me? I don’t think phone support is necessary for all of my customers, but I think email should be answered within an hour.
  • Am I “big industry”? No. I’m nimble and “new economy.” I should get a small office in a recently gentrified part of town, instead of in a mid-city office building.

Keep going. It can be as simple as that. You can get more formal and organized with it later.

http://blog.screamingcircuits.com/

How Should You Mark Your Diodes?

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Current flows through a diode from the anode to the cathode – it will pass current only when the potential on the anode is greater than the potential on the cathode. This is mostly true, but not always.

For the common barrier diode, or rectifier, it’s a pretty safe bet. However, with a zener diode, or  TVS, it’s not true. And, that is why marking a diode, on your PC board, with the plus sign (+) is not good practice.

Take a look at the schematic clip below.

 

 

 

 

 

 

Once you put this circuit on to a PC board, you could legitimately place a plus sign on the anodes of D3 and D4, and another on their cathodes. In the next schematic clip, you could legitimately place both a plus sign, and a minus sign on the anode of D9.

We don’t know what you had in mind, and, we don’t have the schematic. If you use the practice of marking diodes with a (+) on the anode, we don’t have any more information than if you didn’t mark it at all. The same holds for using a minus (-) sign. It really doesn’t give us any information.

So how should you mark your diodes? The best method is to put the diode symbol next to the footprint. on the PC board, as shown below. You can also use “K” to indicate the Cathode, of “A”, to indicate the Anode. “K” is used because “C” could be mistaken for “capacitor.”

D5, in the illustration on the right, would be the preferred method. D7 will work as well. If you don’t have enough room on the board due to spacing constraints, you can put the same information in an assembly drawing.

Ambiguity is the enemy of manufacturers everywhere. Read a bit more on the subject here, or here.

Duane Benson
Help stamp out and eliminate redundancy, and maybe ambiguity, or maybe not

Those Danged LEDs Again

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I was caught by one of my own favorite “simple” traps last week: the dreaded LED footprint mess.

I designed a board based on the Microchip PIC32 — it’s a ChipKIT Arduino-compatible board — that has a number of RGB LEDs on it. I used RGB LED part number LTST-C19HE1WT, from Lite-On. The datasheet is easy to find, and the footprint information is right up front, just the way we like it.


Almost all is well, but I somehow missed taking my own advice and I didn’t double-check the footprint.The footprint I used is more or less 180 degrees off from this one. The common anode is still on pin 4, but the numbering is different. It’s got pin one in the same place, then pin two is in the lower left. Pin 3 is on the same place, and pin 4 is on the upper right. That’s the conventional pin numbering order.

Fortunately, the fix won’t require any mod wires. If I rotate the LEDs 180 degrees, the anode will be in the right spot. All I’ll need to do is adjust my software for the correct R, G and B pin locations.

Duane Benson
I’m dizzy with rotation

http://blog.screamingcircuits.com/

No Need to Waste Parts

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We love parts on reels. Who doesn’t? But reels aren’t always practical — and it’s not just about cost. Cost is, of course, important, but there may be other factors to consider.

Say, for example, you need 20 2.2K Ohm, 5% 0805 resistors. You could buy a small strip of 25 from Digi-Key for $0.32. That gives the 20 you need, plus a few spares just in case.

Alternately, you could buy a digi-reel ( a custom quantity reel). On the reel, you’ll probably want more parts to keep the strip long enough for the feeder. Let’s go with 250 parts for $1.39. Digi-Key charges $7 extra to create a custom reel, so that’s a total of $8.39. Still peanuts.

For a third choice, you could just buy a full reel of 5,000 for $10.64. Still peanuts. If you’re gong to need the same part for a lot of designs, this might make sense. But, there’s more than just cost to consider. You need to store and ship it. Shipping two dozen reels gets pretty expense. Storing and inventorying several dozen reels can become a hassle too. 

The beauty of Digi-Key, Mouser and other places that sell cut strips is that they essentially become your parts warehouse. You pay the 32 cents and never have to worry about whether the part is in your inventory, how many are in your inventory, digging it out of wherever you stuffed the reel when you last needed it.

If you do buy and store the whole reel, you don’t need to ship the entire reel to us. Just cut a strip with the number you need, plus about 5% for that “just in case.”

Of course, if you need a few thousand of the parts go ahead and send us the reel. It would make sense then.

Duane Benson
Reel, reel your part
Solder it, solder it, solder it, solder it
Cost is but a factor

Packing Parts for Personal Manufacturing

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Manufacturing, especially small volume one-time-only builds (like a prototype) is hard. It’s not wise for most people to actively seek out chaos, but that’s what we do, and we do it wisely. That’s what we’ve been doing since 2003.

We do it because it’s hard and because it’s necessary.

A big part of quality manufacturing involves risk reduction. Prototyping and quick-turns inherently add in a lot of risk. While we’ve designed our processes and systems around turning that risk into a quality product, there are a few things that you, the customer, can do to help reduce risk even further.

One of the best things you can do to reduce risk is to prepare a well organized kit, as shown in this video:

You can send us your parts in short, cut strips, like you get from Digikey or Mouser, long continuous strips, full or partial reels, tubes or trays. We machine place from all of those types of packages. What’s important is clear labeling and organization.

Individual, or mixed/loose components are not good, though. Pins get bent, leads get contaminated, values get mixed… Leave them in the strip, even if it’s short. If you’ve got multiple short strips of the same part, we can still machine place. Don’t tape them together. We can deal with them as is.

Duane Benson
Peter Piper Picked a Peck of Pickeled Manufacturing

http://blog.screamingcircuits.com