Wireless audio over 2.4 GHz

Just before the summer my contact at Texas Instruments had the excellent idea to sent me a CC85XXDK-HEADSET development kit. This is a PurePath Wireless Headset Development Kit to evaluate the new wireless audio products from TI based on the CC85xx family of RF micro-controllers. Due to a lack of time I didn't have the opportunity to write about it earlier, but I did give it a try and was impressed.

The kit contains two identical cards, one of which is configured as a master, the other as a slave. Both contain a 2.4 GHz radio and once paired (a simple operation) you can stream high quality stereo audio from the master to the slave. This works exceptionally well according to my non audiophile ears. The cards are each powered from one 1.72 Wh rechargeable li-ion battery, so it is a totally portable system. Charging the batteries is done by hooking the boards up to a USB port. TI claims a continues operation of 22 hours for this system.

I gave it a try in my garden and managed a Line of sight (LOS) distance of some 45+ meters (then I ran out of garden). It will probably go a bit further when the master is higher up from the ground. Occasionally the receiver has drop-outs, then it suddenly goes from full quality audio to complete silence, but this happens only at greater distances or when the data path becomes obstructed. Never did I hear any garbage out of the headphones.

Included in the kit is a little CC Debugger pod (with a funny rubbery feel) that you can use to reprogram the boards. This pod lets you reprogram and configure the boards using a tool called PurePath Wireless Configurator. The purpose of this tool is a bit unclear to me as there doesn't seem to be a whole lot that you can configure, but it is probably useful when you develop your own systems.

If you need a high quality wireless audio link in your system, the CC85xx is definitely worth a look!

Forget about the hardware and learn C

Many people are afraid of 32-bit microcontrollers, or even 16-bit ones. Why? Because they have lots of pins? Lots of registers? If you are an 8-bit PIC assembly language programmer, why do you think it would be more difficult to program a 32-bit controller in assembler? Or is it that the more powerful controllers are meant to be programmed in C instead of assembler? Many people are afraid of C (let’s not even talk about C++). I have been programming in C for too long now to understand why you would be afraid of C, but I do know that it scares many 8-bit developers and newbie programmers.

This is a shame because new controllers nowadays always come with a free C-compiler. It may be limited in some way, but it is free and gets you started. Also, these new controllers come with evaluation kits that are cheaper and cheaper. The MSP-EXP430G2 kit from Texas Instruments for instance costs only $4.30 and includes two (2) 16-bit RISC processors, a PCB with programmer/debugger and a USB cable. Now that’s value for money. Or what about the STM8S-Discovery kit from STMicroelectronics. True, that is a kit for an 8-bit controller, but it costs less than $10 and includes a programmer and a breakaway controller board with capacitive touch sensor.



Hardware is becoming so cheap that it is becoming much like the paper you write on. Unless you’re an artist, you hardly ever care about your paper, the back of an envelope is often good enough. And it will be the same with hardware. You should no longer care about the platform you are working on as long as you can get your application to work. If you learn a language that is supported by all platforms, you can use whatever processor you like instantly and you’re application will be ready much sooner. The language is the pen, write your article and when it is ready send it off to the printer. They will then reproduce your design in the best and cheapest way. They may even decide to change the microcontroller, which is not a problem as your code was written to be portable.

And the winner is…

Last week I did a small survey of microcontroller preferences. Although I had an idea what to expect, there were some surprises in the responses. First of all I received much more reactions than I had hoped for. I would like to say thank you very much to all of you who took the time and effort to reply to this survey! The people that posted a reply (in English!) directly to the blog will find it added to my original post. Those that sent me an email, well, I am very sorry, I am not going to add them all to this blog as there were way, way too many. However, I did spend a few hours reading all the messages and a summary follows here.
What we all want to know now is of course: who won?

But before I will tell you, you will have to read through the following advertisement.

Just joking: the winner is… AVR! Yes, the AVRs received 43% of the votes, while the PIC family lagged behind with 35%. The rest of the votes went to other families of which the MSP430 and the Propeller were mentioned quite often. 8051/2 clones are also reasonably popular.

The main reason for the AVR domination was the available tools. Although free tools exist for many microcontrollers, BASCOM for AVR was mentioned several times and also Arduino. Now this survey originated at Elektor and was read mostly by Elektor readers, so it is biased as Elektor has published quite some projects using BASCOM-AVR, but in general it was felt that the free tools (BASCOM is free only for small executables) for AVR are better than those for PIC. Also the AVR seems to be more easily available and cheaper than a PIC (even more so since Microchip restricted their sampling program), especially important outside the US and Western Europe.

In favour of the PIC was the abundant documentation, examples and free libraries. It is true that Microchip puts a lot of effort in that. On a pure technical level, some people felt that the PIC is less sensitive to noise than the AVR.

Other processors were of course mentioned, but as the survey mainly spoke about PIC and AVR, most people restricted themselves to these two families. However, as stated by several people, if the MSP430 would exist in more DIP packages (only the smallest ones are available in DIP packages), they would definitely prefer it over both PIC and AVR. Surprisingly to me the Propeller from Parallax was mentioned a few times too. Personally I think of this processor more as a sort of freak processor and I would not easily invest time and money in it. Maybe the future proves me wrong, what do I know?

Several people liked the Stellaris, now from TI, others love Freescale.

What is very clear from all the responses and which didn’t surprise me much: architectural reasons clearly do not dominate the choice of a controller family. Once people have learned to use a certain microcontroller family and have invested in tools, they are not very likely to switch to another family from another manufacturer just for the fun of it.

So, my next question is: what does it take to make you switch to a competing microcontroller?