Archive for the ‘The Factory Floor’ Category

Exclave: Hardware Testing in Mass Production, Made Easier

Friday, December 21st, 2018

Reputable factories will test 100% of every product shipped. For example, the computer or phone you’re using to read this has had a plug inserted in every connector, along with dozens of internal and external tests run to confirm everything from the correct operation of the CPU to the proper function of the buttons.


A test station at a motherboard factory (2x speed). Every port and connector gets tested.

Even highly automated processes can yield defective units: entropy happens, and constant vigilance is required to guard against it. Even a very stable manufacturing process with a raw defect rate of around 1% is considered unacceptable by any reputable brand. This is one of the elephants in the digital fabrication room – just because a tool is digital doesn’t mean it will fabricate things perfectly with a push of the button. Every tool needs maintenance, and more often than not a skilled operator is required to inspect the final product and polish over rough edges.

To better grasp the magnitude of the factory test problem, consider the software that’s loaded on your computer. How did it get in there? Devices come out of the silicon foundry mostly blank. They typically don’t even have the innate knowledge to traverse a filesystem, much less connect to the Internet to download an update. Yet everyone has had the experience of waiting for an update to download and install. Factories must orchestrate a much more time-consuming and complicated process to bootstrap every device made, in order for you to enjoy the privilege of connecting to the Internet to download updates.

One might think, “surely, there must be a standardized way for handling this”.

Shockingly, there isn’t.

How Not To Test a Product

Unfortunately, first-time product makers often make the assumption that either products don’t require 100% testing (because the boards are assembled by robots, and robots don’t make mistakes, right?), or there is some otherwise standardized way to handle the initial firmware upload. Once upon a time, I was called upon to intervene on a factory test for an Arduino-derivative product, where the original test specification was literally “plug the device into the USB port of [your] laptop, and type in this AVRDUDE command to load code, and then type in another AVRDUDE command to set the fuses, and then use a multimeter to check the voltages on these two test points”. The test documentation was literally two photographs of the laptop screen and a paragraph of text. The product’s designer argued to the factory that this was sufficient because it it’s really quick and reliable: he does it in under two minutes, how could any competent factory that handles products with AVR chips not have heard of AVRDUDE, and besides he encountered no defects in the half dozen prototypes he produced by hand. This is in addition to an over-arching attitude of “whatever, I’m the smart guy who comes up with the ideas, just get your minimum-wage Chinese laborers to stop messing them up”.

The reality is that asking someone to manually run commands from a shell and read a meter for hours on end while expecting zero defects is neither humane nor practical. Furthermore, assuming the ability and judgment to run command line scripts isn’t realistic; testing is time-consuming, and thus often the least-skilled, lowest wage laborers are employed for the process. Ironically, there is no correlation between the skills required to assemble a computer, and the skills required to operate a computer. Thus, in order for the factory to meet the product designer’s expectation of low labor cost with simultaneously high quality, it’s up to the product designer to come up with an automated, fool-proof test jig.

Introducing the Test Jig: The Product Behind the Product

“Test jig” is a generic term any tool designed to assist with production testing. However, there is a basic format for a test jig chassis, and demand for test jig chassis is so high in places like Shenzhen that entire cottage industries have sprung up to support the demand. Most circuit board test jigs look a bit like this:


Above: NeTV2 circuit board test jig

And the short video below highlights the spring-loaded pogo pins of the test jig, along with how a circuit board is inserted into a test jig and clamped in place for testing.


Above: Inserting an NeTV2 PCB into its test jig.

As you can see in the video, the circuit board is placed into a precision-milled platter that moves along spring-loaded rails, allowing the board to engage with pogo-pin style test points underneath. As test points consume precious space on the circuit board, the overall mechanical accuracy of the system has to be better than +/-1mm once all tolerances are considered over thousands of cycles of wear and tear, in order to keep the test points a reasonable size (under 2mm in diameter).

The specific test jig shown above measures 12 separate DC voltages, performs a basic JTAG ID code check on the FPGA, loads firmware, and tests the on-board DRAM all in under 20 seconds. It’s the preliminary “fast test” of the NeTV2 product, meant to screen out gross solder faults and it provides an estimated coverage of about 80% of the solder joints on the PCB. The remaining 20% of the solder joints belong principally to connectors, which require a much more labor-intensive manual test to check.

Here’s a look inside the test jig:

If it looks complicated, that’s because it is. Test jig complexity is correlated with product complexity, which is why I like to say the test jig is the “product behind the product”. In some cases, a product designer may spend even more time designing a test jig than they spend designing the product itself. There’s a very large space of problems to consider when implementing a test jig, ranging from test coverage to operator fatigue, and of course throughput and reliability.

Here’s a list of the basic issues to consider when designing a test jig:

  • Coverage: How to test every single feature?
  • UX: Who is interpreting your test data? How to internationalize the UI by using symbols and colors instead of text, and how to minimize operator fatigue?
  • Automation: What’s the quickest way to set up and tear down tests? How to avoid relying on human judgment?
  • Audit & traceability: How do you enforce testing standards? How to incorporate logging and coupons to facilitate material traceability?
  • Updates: What do you do when the tester needs a patch or update? How do you keep the test program in lock-step with the current firmware release?
  • Responsibility: Who is responsible for product quality? How do you create a natural incentive to design-for-test from the very first product sketch?
  • Code Structure: How do you maintain the tester’s code base? It’s tempting to think that test jig code should be write-once, since it’s going into a single device with a limited user base. However, the reality of production is rarely so simple, and it pays to structure your code base so that it’s self-checking, modular, reconfigurable, and reliable.

Each of these bullet points are aspects of test jig design that I have learned from the school of hard knocks.

Read on, and avoid my mistakes.

Coverage

Ideally, a tester should cover 100% of the features of a product. But what, exactly, constitutes a feature? I once designed a product called the Chumby One, and I also designed its test procedure. I tried my best to cover all of its features, but I missed one: the power button. It seemed simple enough – just a switch, what could go wrong? It turns out that over the course of production, the tolerance between the mechanical switch pusher and the electrical switch mechanism had drifted to the point where pushing on the cap would not contact the electrical switch itself, leading to a cohort of returns from that production lot.

Even the simplest of mechanisms is a feature that needs to be tested.

Since that experience, I’ve adopted an “inside/outside” methodology to derive the test feature list. First, I look “inside” the product, going through the schematic and picking key features for testing. The priority is to check for solder faults as quickly as possible, based on the assumption that the constituent components are 100% pre-tested and reliable. Then, I look at the product from the “outside”, as a consumer might approach it. First, I look at the marketing brochure and see what was promised: “world class WiFi performance” demands a different level of test from “product has WiFi”. Then, I try to imagine all the ways a customer might interact with the product – such as pressing the power button – and add those points to the test list. This means every connector needs to have something stuffed in it, every switch pressed, every indicator light must get checked.


Red arrow calls out the mechanical switch pusher that drifted out of tolerance with the corresponding electrical switch

UX

Test jig UX can have a large impact on test throughput and reliability; test operators are human, and like all humans are susceptible to fatigue and boredom. A startup I worked with once told me a story of how a simple UX change drastically improved test throughput. They had a test that would take 10 minutes on average to run, so in order to achieve a net throughput of around 1 minute per unit, they provided the factory 10 testers. Significantly, the test run-time would vary from unit to unit, with a variance of several minutes from unit to unit. Unfortunately, the only indicator of test state was a single light that could either flash or change color. Furthermore, the lighting pattern of units that failed testing bore a resemblance to units that were still running the test, so even when the operator noticed a unit that finished testing, they would often overlook failed units, assuming they were still running the test. As a result, the actual throughput achieved on their first production run was about one unit every 5 minutes — driving up labor costs dramatically.

Once the they refactored the UX to include an audible chime that would play when the test was finished, aggregate test cycle time dropped to a bit over a minute – much closer to the original estimate.

Thus, while one might think UX is just for users, I’ve found it pays to make wireframes and mock-ups for the tester itself, and to spend some developer cycles to create an operator-friendly test program. In some ways, tester UX design is more challenging than the product UX: ideally, you’re creating a UX with icons that are internationally recognizeable, using little or no text, so operators anywhere in the world can just sit down and use it with no special training. Furthermore, you’re trying to create user engagement with something as banal as a test – something that’s literally as boring as watching paint dry. I’ve even gone so far as putting a mini-game in the middle of a long test sequence to keep operators attentive. The mini-game was of course directly relevant to the testing certain hardware sensors, but it was surprisingly effective because the operators would race each other on the mini-game to see who could finish the fastest, boosting throughput and increasing worker happiness.

At the end of the day, factories are powered by humans, and it pays to employ a human-first design process when crafting test programs.

Automation

Human operators are prone to error. The more a test can be automated, the more reliable it can be, and in the long run automation will save money. I once visited a large mobile phone maker’s factory, and witnessed a gymnasium-sized room full of test stations replaced by a pair of fully robotic test stations. Instead of hundreds of operators plugging cables in and checking aspects like screen and camera quality, a delicate ballet of robotic actuators would plug connectors into every port in a fraction of a second, and every feature of the phone from the camera to the GPS is tested in a couple of minutes. The test stations apparently cost about a million dollars to develop, but the empty cavern of idle test jigs sitting next to it was clear testament to the labor cost savings of such a high degree of automation.

At the smaller scales more typical of startups, automation can happen but it needs to be judiciously applied. Every robotic actuator takes time and money to develop, and they are also prone to wear-out and eventual failure. For the Chibitronics Chibi Chip product, there’s a single mechanical switch on the board, and we developed a simple servo mechanism to actuate the plunger. However, despite using a series-elastic spring and a foam pad to avoid over-stressing the servo motor, over time, we’ve found the motor still fails, and operators have disconnected it in favor of manually pushing the button at the right time.


The Chibi Chip test jig


Detail view of the reset switch servo

Indicator lights can also be tricky to test because the lighting conditions in a factory can be highly variable. Sometimes the floor is flooded by sunlight; other times, it’s lit by dim fluorescent lamps or LED bulbs, each with distinct noise signatures. A simple photodetector will be unreliable unless you can perfectly shield the device under test (DUT) from stray light sources. However, if the product’s LEDs can be modulated (with a PWM waveform, for example), the modulation can be detected through an AC-coupled photodetector. This system tends to be more reliable as the AC coupling rejects sunlight, and the modulation frequency can be chosen to be distinct from other stray light noise sources in the factory.

In general, the gold standard for test automation is to put the DUT into a jig, press a button, wait, and then a red or green light indicates if the device passes or fails. For simple products, this should be achievable, but reasonable exceptions should be made depending upon the resources available in a startup to implement tests versus the potential frequency and impact of a particular feature escaping the test process. For example, in the case of NeTV2, the functionality of indicator LEDs and the fan are visually inspected by the operator; but in my judgment, all the components involved have generous tolerances and are less likely to be assembled incorrectly, and there are other points downstream of the PCB test during the assembly process where the LEDs and fan operation will be checked yet again, further reducing the likelihood of these features escaping the test process.

Audit and Traceability

Here’s a typical failure scenario at a factory: one operator is running two testers in parallel. The lunch bell rings, and the operator gets up and leaves without noting the status of the test (if you’ve been doing the same thing over and over for the past four hours and running on an empty belly, you’d do the same thing too). After lunch, the operator sits down again, and has to recall whether the units in front of her have been tested or not. As a result of this arbitrary judgment call, sometimes units that didn’t pass test, or weren’t even tested at all, slip into the tested product bins after a shift change.

This is one of the many reasons why it pays to incorporate some sort of audit and traceability program into the tester and product itself. The exact nature of the program will depend greatly upon the exact nature of the product and amount of developer resources available, but a simple example is structuring the test program so that a serial number isn’t generated for the product until all the tests pass – thus, the serial number is a kind of “coupon” to prove the unit has passed test. In the operator-returning-from-lunch scenario, she just has to check for the presence of a serial number to determine the testing state of a particular unit.


The Chibi Chip uses Bitmarks as a coupon to indicate when they have passed test. The Bitmarks also help prevent warranty fraud and deters cloning.

Sometimes I also burn a log of the test into the product itself. It’s important to make the log a circular buffer that can store more than one test run, because often times products that fail test the first time must be retested several times as it’s reworked and repaired. This way, if a product is returned by a user, I can query the log and see a fairly complete history of the product’s rework experience in the factory. This is incredibly helpful in debugging factory process issues and holding the factory accountable for marginal practices such as re-testing a device multiple times without repairing it, with the hope that they get lucky and get a “pass” out of the tester due to random environmental fluctuations.

Ideally, these logs are sent up to the cloud or a server directly, but that will depend heavily upon the reliability of the Internet connectivity at your facility. Internet is notoriously unreliable in China, especially to servers not located on the mainland, and so sometimes a small startup with limited resources has to make compromises about the extent and nature of audit and traceability achievable on the factory floor.

Updates

Consumer electronic products are increasingly just software wrapped in a plastic shell. While the hardware itself must stabilize months before production, the software in a product continues to evolve, especially in Internet-connected products that support over-the-air updates. Sometimes patches to a product’s firmware can profoundly alter low-level APIs, breaking the factory test program. For example, I had a product once where the audio drivers went through a major upgrade, going from OSS to ALSA. This changed the way the microphone subsystem was accessed, causing the microphone test to fail in production. Thus user firmware updates can also necessitate a tester program update.

If a test jig was engineered as a stand-alone box that requires logging into a terminal to upgrade, every time the software team pushes an update, guess what – you’re hopping on a plane to the factory to log in to the test jig and upgrade it. This is not a sustainable upgrade plan for products that have complex, constantly evolving internal firmware; thus, as the test jig designer, it’s well-advised to build a secure remote upgrade process into the test jig itself.


That’s me about 12 years ago on a factory floor at 2AM debugging a testjig update gone wrong, bringing production to a screeching halt. Don’t be like me; you can do better!

In addition a remote upgrade mechanism, you’re going to need a way to validate the test jig update without having to bring down a production line. In order to help with this, I always keep a physical copy of the production test jig in my office, so I can validate testjig updates from the comfort of my office before pushing them to the production floor. I try my best to keep the local jig an exact copy of what’s on the line; this may involve taking snapshots of the firmware image or swapping out OS drives between development and production versions, or deliberately breaking features that have somehow failed on the production jigs. This process is inspired by the engineers at JPL and NASA who keep an exact copy of Mars-based rovers on Earth, so they can thoroughly test an update before pushing it to the rover on Mars. While this discipline can be inconvenient and incurs the cost of an extra test jig, it’s inevitably cheaper than having to book a last minute flight to your factory to fix things because of an update gone wrong.

As for the upgrade mechanism itself, how fancy and secure you want to get has virtually no limit; I’ve done everything from manual swaps of USB thumb drives that contain the tester configuration data to a private VPN via a dedicated 3G-to-wifi gateway deployed at the factory site. The nature of the product (e.g. does it contain security keys, how often is the product firmware updated) and the funding level of your organization will heavily influence the architecture of the upgrade process.

Responsibility

Given how much effort it takes to build a good test jig, it’s tempting to free up precious developer resources by simply outsourcing the test jig to a third party. I’ve almost never found this to be a good idea. First of all, nobody but the developer knows what skeletons are hidden in a product’s closet. There’s what’s written in the spec, but then there is how faithfully the spec was implemented. Of course, in an ideal world, all specs were perfectly met, but only the developer has a true sense of how spot-on the implementation ended up. This drives the second point, which is avoiding the blame game. By throwing tests over the fence to a third party, if a test isn’t easy to implement or is generating false results, it’s easy to get into a finger-pointing exercise over who is at fault: the developer for not meeting the specs, or the test developer for not being creative enough to implement the test without necessitating design changes.

However, when the developer knows they are ultimately on the hook for the test jig, from day one the developer thinks about design for test. Where will the test points go? How do we make internal state easily visible? What bring-up sequence gives us the most test coverage in the shortest amount of time? By making the developer responsible for the test jig, the test program comes together as the product matures. Bring-up scripts used to validate the product are quickly converted to factory tests, and overall the product achieves a higher standard of testability while saving the money and resources that would otherwise be spent trying to coordinate between two parties with conflicting self-interests.

Code Structure

It’s tempting to think about a test jig as a pile of write-once code that doesn’t need to be maintainable. For simple products, one can definitely get away with this mentality. However, I’ve been bitten more than once by fragile code bases inside production testers. The most typical scenario where things break is when I have to change the order of tests, in order to prioritize testing problematic features first. It doesn’t make sense to test a dozen high-yielding features before running a test on a feature with a known yield issue. That just wastes operator time, and runs up the cost of production.

It’s also hard to predict before production what the most frequent mode of failure would be – after all, any failures you could have anticipated would already be designed out! So, quite often in the middle of an early production run, I’m challenged with having to change the order of tests in a complex sequence of tests to optimize operator time and improve production throughput.

Tests almost always have dependencies – you have to power on the board before you can flash the firmware; you need firmware before you can connect to wifi; you need credentials to connect to wifi; you have to clean up the test credentials before shipping the product. However, if the process that cleans up the test credentials is also responsible for cleaning up any other temporary tester files (for example, a flag that also sets Bluetooth into test mode), moving the wifi test sequence earlier could result in tester configuration files being left on the customer image, potentially leading to unexpected behaviors (such as Bluetooth still being in test mode in the shipping product!).

Thus, it’s helpful to have some infrastructure for tests that keeps each test modular while enforcing dependencies. Although one could write this code every single time from scratch, we encounter this problem so regularly that Sean ‘Xobs’ Cross set out to create a testjig management system to solve this problem “once and for all”. The result is a project he calls Exclave, with the idea being that Exclave – like an actual geographical exclave – is a tiny bit of territory that you can retain control of inside a foreign factory.

Introducing Exclave

Exclave is a scaffold designed to give structure to an otherwise amorphous blob of test code, while minimizing the amount of overhead required of the product designer to achieve this structure. The basic features of Exclave are as follows:

  • Code Re-use. During product bring-up, designers write simple scripts to validate each feature individually. Exclave attempts to re-use these scripts by making no assumption about the language used to write them. Python, C, Bash, Node.js, Rust – all are welcome, so long as they run on a command line and can return an exit code.
  • Automated dependency resolution. Each test routine is associated with a “.test” descriptor which describes the dependencies and timeout for a given script, which are then automatically resolved by Exclave.
  • Scenario management. Test descriptors are strung together into scenarios, which can be selected dynamically based on the real-time requirements of the factory.
  • Triggers. Typically a test is started by pressing a button, but Exclave’s flexible triggering system also allows tests to start on other cues, such as hot-plug events.
  • Multiple UI targets. Test jig UI can range from a red/green light to a serial console device to a full graphical interface running on a monitor. Exclave has a system for interpreting test results and driving multiple UI sinks. This allows for fast product debugging by attaching a GUI (via an HDMI monitor or laptop) while maintaining compatibility with cost-efficient LED indicators favored for production scale-up.


Above: Exclave helps migrate lab-bench validation code to production-grade factory tests.

To get a little flavor on what Exclave looks like in practice, let’s look at a couple of the tests implemented in the NeTV2 production test flow. First, the production test is split into two repositories: the test descriptors, and the graphical UI. Note that by housing all the tests in github, we also solve the tester upgrade problem by providing the factory with a set git repo management scripts mapped to double-clickable desktop icons.

These repositories are installed on a Raspberry Pi contained within the test jig, and Exclave is started on boot as a systemd service. The service runs a simple script that fires up Exclave in a target directory which contains a “.jig” file. The “netv2.jig” file specifies the default scenario, among other things.

Here’s an example of what a quick test scenario looks like:

This scenario runs a variety of scripts in different languages that: turn on the device (bash/C), checks voltages (C), checks ID code of the FPGA (bash/openOCD), loads a test bitstream (bash/openOCD), checks that the REPL shell can start on the FPGA (Expect/TCL), and then runs a RAM test (Expect/TCL) before shutting the board down (bash/C). Many of these scripts were copied directly from code used during board bring-up and system validation.

A basic operation that’s surprisingly tricky to do right is checking for terminal interaction (REPL shell) via serial port. Writing a C or bash script that does this correctly and gracefully handles all error cases is hard, but fortunately someone already solved this problem with the “Expect” TCL extension. Here’s what the REPL shell test descriptor looks like in Exclave:

As you can see, this points to a couple other tests as dependencies, sets a time-out, and also designates the location of the Expect script.

And this is what the Expect script looks like:

This one is a bit more specialized to the NeTV2, but basically, it looks for the NeTV2 tester firmware shell prompt, which is “TESTER_NX8D>”; the system will attempt to recover this prompt by sending a carriage-return sequence once every two seconds and searching for this special string in return. If it receives the string “BIOS” instead, this indicates that the NeTV2 failed to boot and escaped into the ROM BIOS, probably due to a RAM error; at which point, the Expect script prints a bunch of JSON, which is automatically passed up to the UI layer by Exclave to create a human-readable error message.

Which brings us to the interface layer. The NeTV2 jig has two options for UI: a set of LEDs, or an HDMI monitor. In an ideal world, the total amount of information an operator needs to know about a board is if it passed or failed – a green or red LED. Multiple instances of the test jig are needed when a product enters high volume production (thousands of units per day), so the cost of each test jig becomes a factor during production scale-up. LEDs are orders of magnitude cheaper than an HDMI monitor, and in general a test jig will cost less than an HDMI monitor. So LEDs instead of an HDMI monitor for UI can dramatically slash the cost to scale up production. On the other hand, a pair of LEDs does not give enough information to diagnose what’s gone wrong with a bad board. In a volume production scenario, one would typically collect the (hopefully small) fraction of failed boards and bring them to a secondary station where a more skilled technician debugs them. Exclave allows the same jig used in production to be placed at the debug station, but with an HDMI monitor attached to provide valuable detailed error reports.

With Exclave, both UI are integrated seamlessly using “.interface” files. Below is an example of the .interface file that starts up the http daemon to enable JSON debugging via an HDMI monitor.

In a nutshell, Exclave contains an event reporting system, which logs events in a fashion similar to Linux kernel messages. Events are tagged with metadata, such as severity, and the events are broadcast to interface handlers that further refine them for the respective UI element. In the case of the LEDs, it just listens for “START” [a scenario], “FAIL” [a test], and “FINISH” [a scenario] events, and ignores everything else. In the case of the HDMI interface, a browser configured to run in kiosk mode is pointed to the correct localhost webpage, and a jquery-based HTML document handles the dynamic generation of the UI based upon detailed messages from Exclave. Below is a screenshot of what the UI looks like in action.

The UI is deliberately brutalist in design, using color to highlight only the most important messages, and also includes audible alerts so that operators can zone out while the test runs.

As you can see, the NeTV2 production tester tests everything – from the LEDs to the Ethernet, to features that perhaps few people will ever use, such as the SD card slot and every single GPIO pin. Thanks to Exclave, I was able to get this complex set of tests up and running in under a month: the first code commit was made on Oct 13, 2018, and by Nov 7, I was largely just tweaking tests for performance, and to reflect operational realities discovered on the factory floor.

Also, for the hardware-curious, I did design a custom “hat” for the Raspberry Pi to add several ADC channels and various connectors to facilitate testing. You can check out the source for the tester hat at the Alphamax github repo. I had six of these boards built; five of them have found their way into various parts of the NeTV2 production flow, and if I still have one spare after production is stabilized, I’m planning on installing a replica of a tester at HAX in Shenzhen. That way, those curious to find out more about Exclave can walk up to the tester, log into it, and poke around (assuming HAX agrees to this).

Let’s Stop Re-Inventing the Test Jig!
The unspoken secret of hardware is that behind every product, there’s a robust test jig making sure that every unit shipped to end customers meets quality standards. Hardware startups that don’t anticipate the importance and difficulty of creating such a tester often encounter acute (and sometimes fatal) growing pains. Anytime I build more than a few copies of a piece of hardware, I know I’m going to need a test jig – even for bespoke, short-run products like a conference badge.

After spending months of agony re-inventing the wheel every time we shipped a product, Xobs decided to create Exclave. It’s still a work in progress, but by now it’s been used as the production test infrastructure for several volume products, including the Chibi Chip, Chibi Scope, Tomu, The Phage Blinky Badge, and now NeTV2 (those are all links to the actual Exclave test scripts for each of the respective products — open source ftw!). I feel Exclave has come along far enough that it’s time to invite more users to join the Exclave community and give it a try. The code is located on github and is 100% open source, and it’s written in Rust entirely by Xobs. It’s my hope that Exclave can mature into a tool and a community that will save countless Makers and small hardware startups the teething pains of re-inventing the test jig.


Production-proven testjigs that run Exclave. Clockwise from top-right: NeTV2, Chibi Chip, Chibi Scope, Tomu, and The Phage Blinky Badge. The badge tester has even survived a couple of weeks exposed to the harsh elements of the desert as a DIY firmware updating station!

New US Tariffs are Anti-Maker and Will Encourage Offshoring

Tuesday, June 19th, 2018

The new 25% tariffs announced by the USTR, set to go into effect on July 6th, are decidedly anti-Maker and ironically pro-offshoring. I’ve examined the tariff lists (List 1 and List 2), and it taxes the import of basic components, tools and sub-assemblies, while giving fully assembled goods a free pass. The USTR’s press release is careful to mention that the tariffs “do not include goods commonly purchased by American consumers such as cellular telephones or televisions.”

Think about it – big companies with the resources to organize thousands of overseas workers making TVs and cell phones will have their outsourced supply chains protected, but small companies that still assemble valuable goods from basic parts inside the US are about to see significant cost increases. Worse yet educators, already forced to work with a shoe-string budget, are going to return from their summer recess to find that basic parts, tools and components for use in the classroom are now significantly more expensive.


Above: The Adafruit MetroX Classic Kit is representative of a typical electronics education kit. Items marked with an “X” in the above image are potentially impacted by the new USTR tariffs.

New Tariffs Reward Offshoring, Encourage IP Flight

Some of the most compelling jobs to bring back to the US are the so-called “last screw” system integration operations. These often involve the complex and precise process of integrating simple sub-assemblies into high-value goods such as 3D printers or cell phones. Quality control and IP protection are paramount. I often advise startups to consider putting their system integration operations in the US because difficult-to-protect intellectual property, such as firmware, never has to be exported if the firmware upload operation happens in the US. The ability to leverage China for low-value subassemblies opens more headroom to create high-value jobs in the US, improving the overall competitiveness of American companies.

Unfortunately, the structure of the new tariffs are exactly the opposite of what you would expect to bring those jobs back to the US. Stiff new taxes on simple components, sub-assemblies, and tools like soldering irons contrasted against a lack of taxation on finished goods pushes business owners to send these “last screw” operation overseas. Basically, with these new tariffs the more value-add sent outside the borders of the US, the more profitable a business will be. Not even concerns over IP security could overcome a 25% increase in base costs and keep operations in the US.

It seems the intention of the new tariff structure was to minimize the immediate pain that voters would feel in the upcoming mid-terms by waiving taxes on finished goods. Unfortunately, the reality is it gives small businesses that were once considering setting up shop in the US a solid reason to look off-shore, while rewarding large corporations for heavy investments in overseas operations.

New Tariffs Hurt Educators and Makers

Learning how to blink a light is the de-facto introduction to electronics. This project is often done with the help of a circuit board, such as a Microbit or Chibi Chip, and a type of light known as an LED. Unfortunately, both of those items – simple circuit boards and LEDs – are about to get 25% more expensive with the new tariffs, along with other Maker and educator staples such as capacitors, resistors, soldering irons, and oscilloscopes. The impact of this cost hike will be felt throughout the industry, but most sharply by educators, especially those serving under-funded school districts.


Above: Learning to blink a light is the de-facto introduction to electronics, and it typically involves a circuit board and an LED, like those pictured above.

Somewhere on the Pacific Ocean right now floats a container of goods for ed-tech startup Chibitronics. The goods are slated primarily for educators and Makers that are stocking up for the fall semester. It will arrive in the US the second week of July, and will likely be greeted by a heavy import tax. I know this because I’m directly involved in the startup’s operations. Chibitronics’ core mission is to serve the educator market, and as part of that we routinely offered deep discounts on bulk products for educators and school systems. Now, thanks to the new tariffs on the basic components that educators rely upon to teach electronics, we are less able to fulfill our mission.

A 25% jump in base costs forces us to choose between immediate price increases or cutting the salaries of our American employees who support the educators. These new tariffs are a tax on America’s future – it deprives some of the most vulnerable groups of access to technology education, making future American workers less competitive on the global stage.


Above: Educator-oriented learning kits like the Chibitronics “Love to Code” are slated for price increases this fall due to the new tariffs.

Protectionism is Bad for Technological Leadership

Recently, I was sent photos by Hernandi Krammes of a network card that was manufactured in Brazil around 1992. One of the most striking features of the card was how retro it looked – straight out of the 80’s, a full decade behind its time. This is a result of Brazil’s policy of protectionist tariffs on the import of high-tech components. While stiff tariffs on the import of microchips drove investment in local chip companies, trade barriers meant the local companies didn’t have to be as competitive. With less incentive to re-invest or upgrade, local technology fell behind the curve, leading ultimately to anachronisms like the Brazilian Ethernet card pictured below.


Above: this Brazilian network card from 1992 features design techniques from the early 80’s. It is large and clunky compared to contemporaneous cards.

Significantly, it’s not that the Brazilian engineers were any less clever than their Western counterparts: they displayed considerable ingenuity getting a network card to work at all using primarily domestically-produced components. The tragedy is instead of using their brainpower to create industry-leading technology, most of their effort went into playing catch-up with the rest of the world. By the time protectionist policies were repealed in Brazil, the local industry was too far behind to effectively compete on a global scale.

Should the US follow Brazil’s protectionist stance on trade, it’s conceivable that some day I might be remarking on the quaintness of American network cards compared to their more advanced Chinese or European counterparts. Trade barriers don’t make a country more competitive – in fact, quite the opposite. In a competition of ideas, you want to start with the best tech available anywhere; otherwise, you’re still jogging to the starting line while the competition has already finished their first lap.

Stand Up and Be Heard

There is a sliver of good news in all of this for American Makers. The list of commodities targeted in the trade war is not yet complete. The “List 2” items – which include all manner of microchips, motors, and plastics (such as 3D printer PLA filament and acrylic sheets for laser cutting) that are building blocks for small businesses and Makers – have yet to be ratified. The USTR website has indicated in the coming weeks they will disclose a process for public review and comment. Once this process is made transparent – whether you are a small business owner or the parent of a child with technical aspirations – I encourage you to please share your stories and concerns on how you will be negatively impacted by these additional tariffs.

Some of the List 2 items still under review include:

9030.31.00 Multimeters for measuring or checking electrical voltage, current, resistance or power, without a recording device
8541.10.00 Diodes, other than photosensitive or light-emitting diodes
8541.40.60 Diodes for semiconductor devices, other than light-emitting diodes, nesoi
8542.31.00 Electronic integrated circuits: processors and controllers
8542.32.00 Electronic integrated circuits: memories
8542.33.00 Electronic integrated circuits: amplifiers
8542.39.00 Electronic integrated circuits: other
8542.90.00 Parts of electronic integrated circuits and microassemblies
8501.10.20 Electric motors of an output of under 18.65 W, synchronous, valued not over $4 each
8501.10.60 Electric motors of an output of 18.65 W or more but not exceeding 37.5 W
8501.31.40 DC motors, nesoi, of an output exceeding 74.6 W but not exceeding 735 W
8544.49.10 Insulated electric conductors of a kind used for telecommunications, for a voltage not exceeding 80 V, not fitted with connectors
8544.49.20 Insulated electric conductors nesoi, for a voltage not exceeding 80 V, not fitted with connectors
3920.59.80 Plates, sheets, film, etc, noncellular, not reinforced, laminated, combined, of other acrylic polymers, nesoi
3916.90.30 Monafilament nesoi, of plastics, excluding ethylene, vinyl chloride and acrylic polymers

Here’s some of the “List 1” items that are set to become 25% more expensive to import from China, come July 6th:

Staples used by every Maker or electronics educator:

8515.11.00 Electric soldering irons and guns
8506.50.00 Lithium primary cells and primary batteries
8506.60.00 Air-zinc primary cells and primary batteries
9030.20.05 Oscilloscopes and oscillographs, specially designed for telecommunications
9030.33.34 Resistance measuring instruments
9030.33.38 Other instruments and apparatus, nesoi, for measuring or checking electrical voltage, current, resistance or power, without a recording device
9030.39.01 Instruments and apparatus, nesoi, for measuring or checking

Circuit assemblies (like Microbit, Chibi Chip, Arduino):

8543.90.68 Printed circuit assemblies of electrical machines and apparatus, having individual functions, nesoi
9030.90.68 Printed circuit assemblies, NESOI

Basic electronic components:

8532.21.00 Tantalum fixed capacitors
8532.22.00 Aluminum electrolytic fixed capacitors
8532.23.00 Ceramic dielectric fixed capacitors, single layer
8532.24.00 Ceramic dielectric fixed capacitors, multilayer
8532.25.00 Dielectric fixed capacitors of paper or plastics
8532.29.00 Fixed electrical capacitors, nesoi
8532.30.00 Variable or adjustable (pre-set) electrical capacitors
8532.90.00 Parts of electrical capacitors, fixed, variable or adjustable (pre-set)
8533.10.00 Electrical fixed carbon resistors, composition or film types
8533.21.00 Electrical fixed resistors, other than composition or film type carbon resistors, for a power handling capacity not exceeding 20 W
8533.29.00 Electrical fixed resistors, other than composition or film type carbon resistors, for a power handling capacity exceeding 20 W
8533.31.00 Electrical wirewound variable resistors, including rheostats and potentiometers, for a power handling capacity not exceeding 20 W
8533.40.40 Metal oxide resistors
8533.40.80 Electrical variable resistors, other than wirewound, including rheostats and potentiometers
8533.90.80 Other parts of electrical resistors, including rheostats and potentiometers, nesoi
8541.21.00 Transistors, other than photosensitive transistors, with a dissipation rating of less than 1 W
8541.29.00 Transistors, other than photosensitive transistors, with a dissipation rating of 1 W or more
8541.30.00 Thyristors, diacs and triacs, other than photosensitive devices
8541.40.20 Light-emitting diodes (LED’s)
8541.40.70 Photosensitive transistors
8541.40.80 Photosensitive semiconductor devices nesoi, optical coupled isolators
8541.40.95 Photosensitive semiconductor devices nesoi, other
8541.50.00 Semiconductor devices other than photosensitive semiconductor devices, nesoi
8541.60.00 Mounted piezoelectric crystals
8541.90.00 Parts of diodes, transistors, similar semiconductor devices, photosensitive semiconductor devices, LED’s and mounted piezoelectric crystals
8504.90.75 Printed circuit assemblies of electrical transformers, static converters and inductors, nesoi
8504.90.96 Parts (other than printed circuit assemblies) of electrical transformers, static converters and inductors
8536.50.90 Switches nesoi, for switching or making connections to or in electrical circuits, for a voltage not exceeding 1,000 V
8536.69.40 Connectors: coaxial, cylindrical multicontact, rack and panel, printed circuit, ribbon or flat cable, for a voltage not exceeding 1,000 V
8544.49.30 Insulated electric conductors nesoi, of copper, for a voltage not exceeding 1,000 V, not fitted with connectors
8544.49.90 Insulated electric conductors nesoi, not of copper, for a voltage not exceeding 1,000 V, not fitted with connectors
8544.60.20 Insulated electric conductors nesoi, for a voltage exceeding 1,000 V, fitted with connectors
8544.60.40 Insulated electric conductors nesoi, of copper, for a voltage exceeding 1,000 V, not fitted with connectors

Parts to fix your phone if it breaks:

8537.10.80 Touch screens without display capabilities for incorporation in apparatus having a display
9033.00.30 Touch screens without display capabilities for incorporation in apparatus having a display
9013.80.70 Liquid crystal and other optical flat panel displays other than for articles of heading 8528, nesoi
9033.00.20 LEDs for backlighting of LCDs
8504.90.65 Printed circuit assemblies of the goods of subheading 8504.40 or 8504.50 for telecommunication apparatus

Power supplies:

9032.89.60 Automatic regulating or controlling instruments and apparatus, nesoi
9032.90.21 Parts and accessories of automatic voltage and voltage-current regulators designed for use in a 6, 12, or 24 V system, nesoi
9032.90.41 Parts and accessories of automatic voltage and voltage-current regulators, not designed for use in a 6, 12, or 24 V system, nesoi
9032.90.61 Parts and accessories for automatic regulating or controlling instruments and apparatus, nesoi
8504.90.41 Parts of power supplies (other than printed circuit assemblies) for automatic data processing machines or units thereof of heading 8471

Why I’m Using Bitmarks on my Products

Friday, October 13th, 2017

One dirty secret of hardware is that a profitable business isn’t just about design innovation, or even product cost reduction: it’s also about how efficiently one can move stuff from point A to B. This explains the insane density of hardware suppliers around Shenzhen; it explains the success of Ikea’s flat-packed furniture model; and it explains the rise of Amazon’s highly centralized, highly automated warehouses.

Unfortunately, reverse logistics – the system for handling returns & exchanges of hardware products – is not something on the forefront of a hardware startup’s agenda. In order to deal with defective products, one has to ship a product first – an all-consuming goal. However, leaving reverse logistics as a “we’ll fix it after we ship” detail could saddle the venture with significant unanticipated customer support costs, potentially putting the entire business model at risk.

This is because logistics are much more efficient in the “forward” direction: the cost of a centralized warehouse to deliver packages to an end consumer’s home address is orders of magnitude less than it is for a residential consumer to mail that same parcel back to the warehouse. This explains the miracle of Amazon Prime, when overnighting a pair of hand-knit mittens to your mother somehow costs you $20. Now repeat the hand-knit mittens thought experiment and replace it with a big-screen TV that has to find its way back to a factory in Shenzhen. Because the return shipment can no longer take advantage of bulk shipping discounts, the postage to China is likely more than the cost of the product itself!

Because of the asymmetry in forward versus reverse logistics cost, it’s generally not cost effective to send defective material directly back to the original factory for refurbishing, recycling, or repair. In many cases the cost of the return label plus the customer support agent’s time will exceed the cost of the product. This friction in repatriating defective product creates opportunities for unscrupulous middlemen to commit warranty fraud.

The basic scam works like this: a customer calls in with a defective product and gets sent a replacement. The returned product is sent to a local processing center, where it may be declared unsalvageable and slated for disposal. However, instead of a proper disposal, the defective goods “escape” the processing center and are resold as new to a different customer. The duped customer then calls in to exchange the same defective product and gets sent a replacement. Rinse lather repeat, and someone gets rich quick selling scrap at full market value.

Similarly, high-quality counterfeits can sap profits from companies. Clones of products are typically produced using cut-rate or recycled parts but sold at full price. What happens when customers then find quality issues with the clone? That’s right – they call the authentic brand vendor and ask for an exchange. In this case, the brand makes zero money on the customer but incurs the full cost of supporting a defective product. This kind of warranty fraud is pandemic in smart phones and can cost producers many millions of dollars per year in losses.


High-quality clones, like the card on the left, can cost businesses millions of dollars in warranty fraud claims.

Serial numbers help mitigate these problems, but it’s easy to guess a simple serial number. More sophisticated schemes tie serial numbers to silicon IDs, but that necessitates a system which can reliably download the serialization data from the factory. This might seem a trivial task but for a lot of reasons – from failures in storage media to human error to poor Internet connectivity in factories – it’s much harder than it seems to make this happen. And for a startup, losing an entire lot of serialization data due to a botched upload could prove fatal.

As a result, most hardware startups ship products with little to no plan for product serialization, much less a plan for reverse logistics. When the first email arrives from an unhappy customer, panic ensues, and the situation is quickly resolved, but by the time the product arrives back at the factory, the freight charges alone might be in the hundreds of dollars. Repeat this exercise a few dozen times, and any hope for a profitable run is rapidly wiped out.

I’ve wrestled with this problem on and off through several startups of my own and finally landed on a solution that looks promising: it’s reasonably robust, fraud-resistant, and dead simple to implement. The key is the bitmark – a small piece of digital data that links physical products to the blockchain.

Most people are familiar with blockchains through Bitcoin. Bitcoin uses the blockchain as a public ledger to prevent double-spending of the same virtual coin. This same public ledger can be applied to physical hardware products through a bitmark. Products that have been bitmarked can have their provenance tracked back to the factory using the public ledger, thus hampering cloning and warranty fraud – the physical equivalent of double-spending a Bitcoin.

One of my most recent hardware startups, Chibitronics has teamed up with Bitmark to develop an end-to-end solution for Chibitronics’ newest microcontroller product, the Chibi Chip.

As an open hardware business, we welcome people to make their own versions of our product, but we can’t afford to give free Chibi Chips to customers that bought cut-rate clones and then report them as defective for a free upgrade to an authentic unit. We’re also an extremely lean startup, so we can’t afford the personnel to build a full serialization and reverse logistics system from scratch. This is where Bitmark comes in.

Bitmark has developed a turn-key solution for serialization and reverse logistics triage. They issue us bitmarks as lists of unique, six-word phrases. The six-word phrases are less frustrating for users to type in than strings of random characters. We then print the phrases onto labels that are stuck onto the back of each Chibi Chip.


Bitmark claim code on the back of a Chibi Chip

We release just enough of these pre-printed labels to the factory to run our authorized production quantities. This allows us to trace a bitmark back to a given production lot. It also prevents “ghost shifting” – that is, authorized factories producing extra bootleg units on a midnight shift that are sold into the market at deep discounts. Bitmark created a website for us where customers can then claim their bitmarks, thus registering their product and making it eligible for warranty service. In the event of an exchange or return, the product’s bitmark is updated to record this event. Then if a product fails to be returned to the factory, it can’t be re-claimed as defective because the blockchain ledger would evidence that bitmark as being mapped to a previously returned product. This allows us to defer the repatriation of the product to the factory. It also enables us to use unverified third parties to handle returned goods, giving us a large range of options to reduce reverse logistics costs.

Bitmark also plans to roll out a site where users can verify the provenance of their bitmarks, so buyers can check if a product’s bitmark is authentic and if it has been previously returned for problems before they buy it. This increases the buyer’s confidence, thus potentially boosting the resale value of used Chibi Chips.

For the cost and convenience of a humble printed label, Bitmark enhances control over our factories, enables production lot traceability, deters cloning, prevents warranty fraud, enhances confidence in the secondary market, and gives us ample options to streamline our reverse logistics.

Of course, the solution isn’t perfect. A printed label can be peeled off one product and stuck on another, so people could potentially just peel labels off good products and resell the labels to users with broken clones looking to upgrade by committing warranty fraud. This scenario could be mitigated by using tamper-resistant labels. And for every label that’s copied by a cloner, there’s one victim who will have trouble getting support on an authentic unit. Also, if users are generally lax about claiming their bitmark codes, it creates an opportunity for labels to be sparsely duplicated in an effort to ghost-shift/clone without being detected; but this can be mitigated with a website update that encouraging customers to immediately register their bitmarks before using the web-based services tied to the product. We also have to exercise care in handling lists of unclaimed phrases because, until a customer registers their bitmark claim phrase in the blockchain, the phrases have value to would-be fraudsters.

But overall, for the cost and convenience, the solution outperforms all the other alternatives I’ve explored to date. And perhaps most importantly for hardware startups like mine that are short on time and long on tasks, printing bitmarks is simple enough for us to implement that it’s hard to justify doing anything else.

Disclosure: I am a technical advisor and shareholder of Bitmark.

WIRED Documentary on Shenzhen

Wednesday, June 8th, 2016

WIRED is now running a multi-part video documentary on Shenzhen:

This shoot was a lot of fun, and it was a great pleasure working with Posy and Jim. I think their talent as producer and director really show through. They also did a great job editing my off-the-cuff narratives. The spot in the video where I’m pointing out Samsung parts isn’t matched to the b-roll of Apple parts, but in their defense I was moving so fast through the market that Jim couldn’t capture all the things I was pointing at.

I haven’t seen the whole documentary myself (I was just called in to give some tours of the market and answer a few questions in my hotel room), so I’m curious and excited to see where this is going! Especially because of the text chosen for printing during my Moore’s Law explanation at 3:13 — “ALL PROPRIETARY AND NO OPEN SOURCE MAKES INNOVATION A SLOW PROCESS.”

:)

Preparing for Production of The Essential Guide To Electronics in Shenzhen

Sunday, March 13th, 2016

The crowd funding campaign for The Essential Guide to Electronics in Shenzhen is about to wrap up in a couple of days.

I’ve already started the process of preparing the printing factory for production. Last week, I made another visit to the facility, to discuss production forecasts, lead time and review the latest iteration of the book’s prototype. It’s getting pretty close. I’m now using a heavy, laminated cardstock for the tabbed section dividers to improve their durability. The improved tabs pushes up the cost of the book, and more significantly, pushes the shipping weight of the book over 16 oz, which means I’m now paying a higher rate for postage. However, this is mostly offset by the higher print volume, so I can mitigate the unexpected extra costs.

The printing factory has a lot of mesmerizing machines running on the floor, like this automatic cover binder for perfect-bound books:

And this high speed two-color printing press:

This is probably the very press that the book will be printed on. The paper moves so fast that it’s just a blur as an animated gif. I estimate it does about 150 pages per minute, and each page is about a meter across, which gives it an effective throughput of over a thousand book-sized pages per minute. Even for a run of a couple thousand books, this machine would only print for about 15 minutes before it has to stop for a printing plate swap, an operation which takes a few minutes to complete. This explains why books don’t get really cheap until the volume reaches tens of thousands of copies.

Above is the holepunch used for building prototypes of ring-bound books. The production punch is done using a semi-automated high-volume die-cutter, but for the test prints, this is the machine used to punch out the holes.

The ring binding itself is done by a fairly simple machine. The video above shows the process used to adjust the machine’s height for a single shot on the prototype book. In a production scenario, there would be a few workers on the table to the left of the binding machine aligning pages, adding the covers, and inserting the ring stock. Contrast this to the fully automated perfect binding machine shown at the top of this post — ring binding is a much more expensive binding style in this factory, since they haven’t automated the process (yet).

I also got a chance to see the machine that gilds and debosses the book cover. It’s a bit of a different process than the edge-gilding I described in the previous post about designing the cover.

Here, an aluminum plate is first made with the deboss pattern. It looks pretty neat — I’ve half a mind to ask the laoban if he’d save the used plates for me to keep as a souvenir, although the last thing I need in my tiny flat in Singapore is more junk.

The plate is then glued into a huge press. This versatile machine can do debossing, die cutting, and gilding on sheets of paper as large as A0. For the gilding operation, the mounting face for the aluminum plate is heated to around 130 degrees Celsius.

I think it’s kind of cute how they put good luck seals all over the machines. The characters say “kai gong da ji” which literally translated means “start operation, big luck”. I don’t know what’s the underlying reason — maybe it’s to wish good luck on the machine, the factory, or the operator; or maybe fix its feng shui, or some kind of voodoo to keep the darned thing from breaking down again. I’ll have to remember to ask what’s the reason for the sticker next time I visit.

Once at temperature, the gilding foil is drawn over the plate, and the alignment of the plate is determined by doing a test shot onto a transparent plastic sheet. The blank cover is then slid under the sheet, taped in place, and the clear sheet removed.

The actual pressing step is very fast — so fast I didn’t have a chance to turn my camera into video mode, so I only have a series of three photos to show the before, pressing, and after states.

And here’s a photo of me with the factory laoban (boss), showing off the latest prototype. I’ve often said that if you can’t meet the laoban, the factory’s too big for you. Having a direct relationship with the laoban has been helpful for this project; he’s very patiently addressed all my strange customization requests, and as a side bonus he seems to know all the good restaurants in the area so the after-work meals are usually pretty delicious.

I’m looking forward to getting production started on the book, and getting all the pledge rewards delivered on-time. Now’s the last chance to back the crowd funding campaign and get the book at a discounted price. I will order some extra copies of the book, but it’s been hard to estimate demand, so there’s a risk the book could sell out soon after the campaign concludes.