Sunday, December 25, 2011

A Propeller for Christmas

I got a VERY unexpected surprise for Christmas, . . . even though I ordered it for myself.

I have been playing with micro processors for the last few months, with the idea that at some point they will control my beacons or other Amateur Radio Projects and Devices. So far, I have been using the Arduino and Teensy micros for most of my exploration and learning.

One of the Blogs that I follow is Wardy's Projects, he posted about a new device for him. It is the Propeller from Parallax. My initial reaction was; yeah, right, . . another "me-too micro". And, it was made by same people that made the Stamp? The Stamp is one micro that I just never got around to exploring. But, as per Wardy, the Propeller promises to have some interesting capabilities that I would find useful.

Note: while writing the post, the Parallax site appears to be down, what's with that!

After doing a little more reading/research, I decided to order a Propeller "Gadget Gangster" it was about $50.00 and it appeared similar to the Arduino Shield that I had been using. I picked up the order at the post box on Christmas eve.

Some of the attributed of the Propeller Micro Processor that I though would be interesting, are:
  • The processor has 8 cores, known as COG's, each is an independent processor which can run it's own code.
  • The master clock can run up to 80mHz (or much slower, to save power), and some people over clock it even faster.
  • Each COG can control two Frequency Synthesizers, from DC, to an amazing 120mHz.

Some of my concerns were; it does not use "C", it has it own languages called "Spin" and "pasm", although Spin looks a little like "C", . . . it's just another new language to learn.

The Propeller Processor looks like it maybe an ideal Amateur Radio RF Frequency Synthesizer, just ideal for my planned Transmitters, Receivers and Beacons. The raw Propeller Chip is available in DIP and SMT format, for about $8.00.

It took a bit to get the Propeller running (i.e., I am familiar with the Arduino, which obtains its power from the USB cable). By adding a 9Volt Battery and Clip, the hardware installation was complete. Installation of the Propeller IDE software was easy, a download and a few mouse clicks. It did not run, under WINE on my Ubuntu system, it ERRORd with something about the USB could not find the ports. But, there is a download for Linux and it installed quickly. The example and library directories are easily found in the MS directory structure of the first install that I did under WINE.

I clicked on the Frequency Synthesizer example, and its required library, which were loaded into two source TABs on the IDE GUI.

The source files were short and simple, I could see in the source file where "they" set the desired frequency, so therefore, with a quick edit, I picked my favorite frequency: 10.14mHz (typed as "10_140_000", the compiler ignores the under-bars).

I pressed F11, an ERROR! The compiler could not find the USB, pressing F7 fixed the problem. Pressing F11 once again --- out of the speaker across the room came a TONE!!! I had my HF receiver set for upper sideband on 10.1387mHz (the normal QRSS and WISPR receive frequency). - IT WORKED !!

My very unexpected Christmas surprise? - It was so simple.

After modifying the programs a little, I now have a Beacon sending my Call sign with CW, and sending multi-level FSK QRSS signals. Before going live with an antenna, I will need to build a low pass (or band pass) filter for the output. Currently it is just; a Battery, the Propeller, and two short 3 inch wires for an antenna.

And just think, I am only using one of 8 COGs and one of the 16 frequency synthesizers on the processor! I can do a lot more with this thing. Spin is going to take some time to learn, but I think I can like it.

The only downside that I currently see is the Propeller is not 5v TTL, it is a 3.3v CMOS processor. If real TTL levels are necessary; an input 5v TTL can be connected via a 4.7K resistor, for output a TTL driver circuit maybe necessary, and yet some TTL device will work with the CMOS 3.3v output.

I am just getting started with this thing. I am going to have fun with my Propeller in the coming mouths, . . .

Thanks to Wardy, and Santa!



  1. Looks interesting. Can the synthesizer be stepped with sub-1Hz resolution (to generate WSPR signal?)

  2. Hi Eldon,

    Thanks for the mention, I've been getting a few visitors from your blog for a while now - much appreciated.

    I'm a real novice at electronics as I've been teaching myself the world of digital circuits for just over a year now. To have a "Ham guy" mention my blog is a real boost to a noobie's confidence :)

    I'd also suggest you check out the Propeller's TV out and VGA out capabilities -both of which are highly impressive because you can also do sound simultaneously (on the same channel for TV and separately for VGA). I tend to think of the Prop as a DIP-package supercomputer!

    So for you Radio enthusiasts there's the possibility of generating several channels of radio frequencies and then have another cog displaying realtime status info on an old VGA computer screen.

  3. Very Good Wardy

    I like to provide credit where credit is due, your Propeller posts were my inspiration, Thanks.