Advances in DSP over these past couple decades have been responsible for some of our  most important technological leaps — MRI scanners, mobile phones, digital  image sensors, etc. — but despite that, it doesn’t always get the attention or interest it deserves.   Unfortunately, the reason for this bad reputation is woefully clear: most of the literature out there on DSP is extremely opaque, heavily focused on the theoretical not the pratical, and  it all tends to be written by domain experts for domain experts, steeped in their own distinct domain language.  There’s room and a need for all of that … but it does make it pretty rough for non DSP people to take advantage of some of the enormous benefits even the simplest DSP algorithms can offer.

Thankfully, people interested in improving the reliability and usefulness of their data have a friend in Dr. Stephen W. Smith, author of “The Scientist and Engineer’s Guide to Digital Signal Processing“.  Dr. Smith not only provides an excellent overview of many of the key concepts and filters you’ll use solving problems in the real world day to day, but he does it in an extremely easy to understand and accessible way, with an emphasis on implementation not just abstract theory (though the theory is often explained with clarity and reasonable depth as well).  A lot of the most common DSP ‘filters’ and algorithms are covered — FFT, FIR, IIR, moving averages, etc. — and they are all accompanied with intentionally ‘basic’ implementations in code in … well … Basic.

In an particularly enlightened stance, Dr. Smith also takes the unusual step of letting you decide entirely for yourself if this is the right book for you, since the entire book is available online free or charge, chapter by chapter in PDF format!  You can get printed copies of Amazon, and if you find the book useful it’s worth support the author (I ordered my copy 20 minutes after digging into a single chapter), but if you’re on a tight budget, you’ll be bound to appreciate his generous and open gesture!

Any other good DSP resources for beginners out there that your found noteworth?  Toss them up in the comments below so other people can benefit as well!

While this is somewhat of a specialised book, if you have to do any work with image processing (OCR, shape recognition, etc.), there are some good frameworks out there, but there’s hardly an abundance of easily accessible information on the subject if you need to implement something yourself.  Algorithms for Image Processing and Computer Vision (2nd Edition) is one of the better books available, and while — like most specialised technical books — it isn’t cheap, it is a good value given the amount of information it covers in one place.

Microchip has a great app note where they’ve compiled all kinds of useful little SW and HW hacks as a ‘tips and tricks’ guide.  wondering how you can connect a bunch of switches or buttons to a single pin?  They’ve got you covered.  Have a look at Compiled Tips ‘N Tricks yourself to see what problems you can solved differently on your next project.

Digging around for some information on MEMs gyroscope manufacturing processes, I came across this excellent white paper that explains a lot of the options that manufacturers have making low cost gyroscopes.  MEMs is a really fascinating business to be in, with very real manufacturing challenges, but some very unique opportunities as well.  Most of the driving force behind MEMs in recent years has been smart phones — by far the single biggest market for MEMs gyros! — but the DIY and HW world definitely benefits from this since it’s never been cheaper or easier to get high quality motion sensors.  Curious how MEMs gyros are made?  Have a look at: A Critical Review of the Market Status and Industry Challenges of Producing Consumer Grade MEMS Gyroscopes from Invensense.

Our TSL2561 digital light sensor  has always been a popular breakout.  Part of what makes this board so useful is actually the Adafruit driver, and that extra bit of effort that went into providing useful values like ‘lux’ instead of 0..1023 etc.  It’s easy to get raw data out of any sensor, but that’s not always very useful if you want to do something useful with these sensors.  Raw data needs to be converted to real world values, but this often takes more work than everything else in the driver put together, at least if you care about accuracy.

Using the Lux Equation from Taos gives a good overview of what’s involved in taking that raw sensor data and making it useful, taking into account easy to overlook values like the glass attenuation factor, etc.  If you’re interested in things like color correction, Calculating Color Temperature and Illuminance also has some good details on accurately converting RGB sensor data to color temperature.

Part of the motivation behind the new Adafruit Unified Sensor system is to make it easier to give people real world values without having to do all kinds of matrix multiplication yourself … but sometimes it’s useful to see what goes on behinds the scenes, and know how to calculate some of this stuff yourself as well.  All the real magic is in the fine print and the details!

Switching power supplies can offer much better efficiency than linear supplies, but they’re also a bit trickier to get working and require more components and more precise component selection.  How do you evaluate switching more power supply circuits?  In reality there are a lot of parameters to test often requiring specialised equipment — things like a DC load to test efficiency, special probes for your scope, etc. — but there’s a good article at Scope Junction on the topic: Stability Testing A Switching Power Supply.

The articles assumes you have access to some fairly high end equipment (a network analyser, etc.), but it’s an interesting read just to see some of the real world considerations that you need to keep in mind with commercial design and how much testing really goes on (or should go on) in the manufacturing process.

Some manufacturers do this better than others.  I have vivid memories of working as an apps engineer being tasked with helping a Japanese company using a brand new and complex MCU in their product.  Every time I saw an email from them in my inbox (daily) I winced because I knew it would be another incredibly precise question involving very specific values or test conditions and I’d have to call up the chip design team to get the test parameters and see what was up … it was never much fun, but it did instill in me a lot of respect for the testing efforts they went through, and sometimes they were right and identified one or two issues that got past the validation team MCU side.  It was a wakeup call for everyone, but a good one.  Testing matters, and often testing can be as much or more effort than initial product development.

Have any horror stories where you wish you had put more effort into testing yourself or had to compromise because of deadlines and it ended up biting you in the back-end?  Post them up in the comments below!