The Dark Side of Devkits and Single-board Computers

RE: The Dark Side of Devkits and Single-board Computers

johnbeetem — Wed, 19 Feb 2014 00:59:22 GMT

I love SBCs and other development boards. They provide a low-to-medium-cost way to try out a new chip and prove that it's really going to work for your application. If the errata and software support are inadequate for your application, you find that out quickly while you still have time to switch to something else. Sometimes a manufacturer rep will give or loan you a dev board, in which case it's no cost.

One of my favorite examples of SBC success was when I ported a complex data communications product from a Motorola (now Freescale) MC68360 QUICC to an MPC860 PowerQUICC. Approx 98% of the code was application level protocol stuff that was source-code compatible so I only had to rewrite some device-level code. I got that baby working on an MPC860 development board, and you could see the standard software boot up and work like the product-to-be. Doing this took care of the high-risk part of the project: getting the software to work. We got the green light to develop the PowerQUICC board, which didn't have prototypes until months later.

SBCs are a great way to get software working in parallel with the final hardware, so that the two parts converge simultaneously. If your software people have to wait for working hardware, you'll likely miss your market window. Most of the early Raspberry Pi software was developed on Alpha units.

I did something similar with a Spartan-IIE FPGA. I got the key parts of the design working on a Spartan-II FPGA development board, which would actually plug into one of our existing products as a daughter board. It's a great way to get credibility to demonstrate production software running on prototype hardware long before the actual PCBs are designed or fabricated.

RE: The Dark Side of Devkits and Single-board Computers

Former Member — Tue, 18 Feb 2014 23:54:47 GMT

While I do agree that good documentation is a must, any decent engineer is usually prepared to deal with errata in any of documentation, design or silicon. For things as complex as the SoC's that are on today's SBC's, expecting everything to be perfect simply isn't realistic. To take your example of the BBB, most engineers will actually be evaluating the AM3359 and will not be hugely interested in the 109 page BBB_SRM, preferring the 4100+ page AM3359 Technical Reference Manual along with the Datasheet and silicon errata documents.

You also say:

Engineers require sufficient information about how best to use a part. To do so, they need to determine to the point of exhaustion what is actually going on with a part so as to properly use it in a design project

I'd agree with that, however getting at some of that information is likely to require signing some sort of NDA, at which time many of your other points become tenuous at best. For example having to call the manufacturer to get something to work.. Signed the NDA means you've already done that and most likely have access to proper technical support etc.

A compromise, somewhere between Cabe's point and yours seems more realistic. Something like the BBB where you are able to take a proven design and reduce it to what's really necessary for your product may be a very useful thing to have, it may save you effort in both hardware and software development time.

As a possible pointer to things to come, earlier in my career I watched a lot of purpose designed systems fall by the wayside to be replaced by cheap commodity PC's as the brains of some larger system. I certainly don't think today's SBC's are capable of accomplishing the same feat, yet... but I think they might just be a step and a half away.

RE: The Dark Side of Devkits and Single-board Computers

kas.lewis — Tue, 18 Feb 2014 22:00:24 GMT

Reading the last paragraph brings back memories... How many companies I have left behind because I could not get the basics to work. With no documentation your free samples are worthless. I have even been told by a rep from a very big company to ignore their bad website (that had nothing helpful) and email him every time I needed something... well it was simpler to just use someone elses part...

RE: The Dark Side of Devkits and Single-board Computers

DAB — Tue, 18 Feb 2014 19:53:02 GMT

Well put.

SBC development kits are only intended to provide engineers with a simple way to test the capabilities of the processor and ancillary chips on the board.

They should never be embedded into a final design. It might sound like a quick solution, but it is no way to build a product.

I have no problem using Development kits to build up one of a kind laboratory instrument or test rig for some other product or device.

I might even prototype a proposed product using one, but that is as far as you should go.

DAB