Programming the API

Over on the FlexRadio community I was encouraged to write down my experiences of programming with the FlexRadio Smart SDR Application Programming Interface. The result is a fairly extensive document that has been reviewed by FlexRadio technical staff and is now available on the FlexRadio Wiki.

If you are interested in writing your own interface code or would like to better understand how my controller works then you may find it interesting. Definitely for software geeks only :)

Coding progress

I've had a pretty productive week on the Mk II controller software development front. The display panel is now more or less finished:

The layout is more or less identical to the Mk I screen, for the simple reason that it seems to work nicely from an ergonomics perspective. There are a few nice new features that were easier to implement in Windows than as native Arduino code:

• The mute and lock indicators are now small icons that show the status graphically rather than in words.
• The filter display is dynamic - its shape varies as the filter width and shift controls are used. This took a surprising amount of time to write!
• Band and mode selection is now much neater, with a nice pop-up window...

This is brought up by pressing the programmed band/mode switch or by clicking on the mode indicators in the main screen. Band/mode selection is achieved by clicking or touching on the relevant pad.

Pretty well all the code behind the screen is now completed, so I am now somewhat ahead of myself in software terms and I really need to get on with the new PCB layout so I can get that into fab. Can't do that until some hardware arrives on the slow boat from the far east. Thinks... perhaps I should go and make some QSOs and stop sitting in front of this computer all day. Or go flying, or something.

Mk II PCB design

My friend the PCB designer has been busy on the Mk II design. The first task is to create a detailed circuit diagram, which can then be converted into a track layout.

This circuit has some interesting and very useful characteristics:

• It is symmetrical. The same circuit could be used for a PCB with one switch multiplexer, four encoders and a single VFO simply by removing half of the circuit. This will make it much easier to devise a min-controller in due course.
• Similarly, it is easy to create more complex boards using the same circuit "building block" approach.
• The Arduino is mounted directly onto the PCB using its header pins. No additional wiring should be required other than a USB connector to the Arduino and HDMI into the display (if fitted).

The next issue we need to address is the physical layout of the PCB. Ideally I would like to use the front panel that I am currently using for the Mk I controller. Unfortunately, the HDMI connector on the display gets in the way of the push buttons on the left side of the display. I've located a right-angled skinny HDMI adapter that might, just, provide sufficient room. It's on the slow boat from Hong Kong and until it arrives there isn't too much more we can do on the PCB front.

Meanwhile, I am adding code to the Windows side of the Mk II controller. This has thrown up the usual flurry of issues that confronts any software developer but each day a little more functionality is completed. More on this in due course.