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• Editor's Notes
• Quotes and Thoughts
• Tools and Tips
• Freebies and Discounts
• The Rust Programming Language
• Debugging Embedded and Real-Time Systems
• The Binho Nova Multi-Protocol USB Host Adapter
• Failure of the Week
• Jobs!
• Joke for the Week
• About The Embedded Muse

The Embedded Muse now goes to over 40,000 subscribers.

Let's disagree without being disagreeable – Laurene Powell Jobs

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

Gerald DeSantis wrote:

September's giveaway is courtesy of Binho, and is one of their Nova Multi-Protocol USB Host Adapters with accessories (reviewed later in this issue).

Enter via this link.

James Munns is an embedded systems engineer, and Managing Director at Ferrous Systems GmbH in Berlin, Germany. James has experience in a variety of domains, including safety critical avionics, robotics, and gas detection, as well as connected IoT devices.

Ferrous Systems GmbH is the largest software consultancy worldwide focused on the Rust Programming Language. Ferrous Systems provides services in advising, development, and training, and has experience developing embedded systems and systems level software in Rust.

Arnold Berger has a new book out and his publisher graciously sent me a copy. Debugging Embedded and Real-Time Systems is a worthy addition to the literature.

Arnie teaches embedded systems at the University of Washington, and I was stunned to read in this volume that the Circuits 1 students get a breadboard and they actually construct and test circuits. When I went to college circuit theory was entirely theory. A later lab class was a joke of playing with multimeters. So while the pundits complain of education going to hell in a handbasket, my hat is off to the U of W for a class rich in practicum.

This book is really aimed at students, and I think it should be a part of the pedagogy of every CS and EE department. Arnie pushes the idea of using a disciplined approach to debugging. Over the decades I've seen (and have participated in) too many shotgunning sessions. Sometimes these work though more often much time is wasted. And sometimes a "fix" is masking tape over the wrong issue, creating more havoc later.

The book is about debugging embedded systems; not hardware, not software, but both the hardware and the software, which is means it's written assuming the reader is familiar with both. Though it does zero in on each in isolation at times, it's a broadly-focused work that should appeal to all embedded practitioners, especially those at the intersection of the two disciplines.

When it does come to software Arnie's first advice is to write bug-free code. For that he presents a strategy. He admits we'll never be perfect, but the unfortunate truth is that many of us write firmware figuring on long sessions with the debugger instead of employing every means possible to avoid errors.

The same is true for hardware, and he presents a number of ideas for designing the hardware correctly. Some of this will be obvious to old-timers; for newbies, not so much so. An example: Use pullups on the bus to implement a NOP so you can run tests without memory loaded. I prefer a software interrupt instruction, when possible, as that will create write cycles as well. A scope or logic analyzer will show all of the resulting bus activity (if any!).

Chapter five is a good overview of the tools we use. I was surprised that the oscilloscope didn't get its own section, though many references are made to that tool in other places.

One tidbit I've been advocating for years: Keep a debugging log. Have you ever chased a bug for days and find yourself repeating a test, simply because you forgot you ran it? I have. A log documents the process in a disciplined way.

Some concepts will be new to even many experienced hands. Ever hear of SIMICS? It's a fascinating tool I've been following for some years, and I'm told Intel (which owns it) uses it to evaluate most of their products.

Arnie highly praises going to the Embedded Systems Conference. Alas, that show is a shadow of its former self. Once that advice was spot-on. Today I recommend Embedded World (in Germany) as that gathering is huge and dynamic.

Arnie presents lots of anecdotes from his career which makes for fun reading.

Debugging Embedded and Real-Time Systems is a quick and easy read that condenses a lot of useful information into 285 pages. Every student of our profession should read it and embrace the concepts. Experienced readers will pick up useful nuggets as well. If there's one nit to pick it's the $80 price tag, a price that's becoming all too common for tech books. I sheepishly admit my own books are also way too expensive. The Embedded Systems Dictionary, which I co-wrote with Mike Barr, is currently $143 on Amazon. Perhaps that explains its pathetic sales!

Binho sent me one of their Nova Multi-Protocol USB Host Adapters. I wasn't quite sure what such a device is or does, so went to the company's web page, which didn't shed enough light for a dullard like me to understand. A lot of web sites today are very pretty yet they don't clearly state what the company is selling. We used to talk about having an elevator speech: a 15 second explanation of what you do. Too many web sites neglect that.

However, this page gives an excellent description of the Nova. It is basically an interface between a PC's USB port and common interfaces found in embedded systems. In particular, the device can interface to devices that communicate via I2C, SPI, UART, 1-WIRE, and SWI. On one side of the device is a USB connector; on the other is a flat ribbon cable with power and ground signals, plus five pins for connecting to these interfaces.

Pinouts are:

Why would you want to do this? Early in development it may be easier to develop prototype code for a device driver on a PC rather than in the less-friendly cross-development environment. The Nova can also enable automatic testing of devices in an embedded system. And it can be a nice way to download code to flash memory in production.

Steve Jobs taught us that beauty can be combined with functionality, and a few makers of test equipment (notably Saleae's logic analyzers) have profited from that lesson. Binho, too, provides a unit in a slim, elegant metal package, which in turn is shipped in a quite attractive hard case.

A GUI interface named "Mission Control" is available for Windows, Linux and Macs. It's self explanatory. For example, to control an SPI device:

An alternative mode lets you use these 5 pins as GPIO connections or A/D inputs. One can be a DAC. Four can be PWMs with controllable frequency and duty cycle.

The Mission Control GUI is a clean and easy way to interface to the device, but the real power comes from Python libraries that let you write code to send and receive data at speed via the Nova to your hardware. I did not try this, but the web site contains numerous examples, all too long to list here.

You can also drive the Nova from a command terminal like Tera Term.

Binho's web site has very clear step-by-step instructions for installing and using the device. I do wish they were available as a single PDF as I like to keep user manuals on my disk, and prefer random access access rather than stepping through web pages.

At $149 the Nova is a very affordable way to tie a PC to an embedded system using any of these serial interfaces. The GUI is simple and powerful. If you're willing to write some Python code, there's really no limit to the control you could exercise over a device.

Another heart rate fail to complement the one in the last Muse. According to the CDC the max heart rate is 220-(age in years) which means this poor person is negative four billion years old. I guess that means he or she will be born about the time the sun turns into a cinder. I suspect at that time we'll be programming 8051s in C0xFFFFFFFF.

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.

These jokes are archived here.

From Phil Matthews:

Everybody trusts a hardware engineer, except themselves.
Nobody trusts a software engineer, except themselves.

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.