RDS/RBDS FM receiver (external) for traffic conditions

Doug Sutherland doug at proficio.ca
Sun Nov 18 19:11:06 CET 2007


I have the USB FM radio stick.
A USB audio device does appear when it's plugged in.
However, there is no audio until the FM radio app is run.
This does SPI communication with the SI4701 to init
and change its settings.

> They claim it uses standard USBaudio for the sound and that they use the
> HID spec for control interface (which doesn't make a ton of sense to me,
> as it seems backwards, but I have not reviewed the spec).

Why would this be backwards?
HID is human interface, which in this case is buttons on the FM radio
GUI application, you have a stereo/mono select, volume slider, mute button,
up and down frequency tune and scan buttons, a button for configuring the
preset stations, and buttons for preset stations. What is backwards about
this? Audio is standard USB audio, controls are custom "generic USB HID".

> This is also the FM chip used in the M$ Zune, but there doesn't appear
> to have been a lot of progress made on the linux front there.

I haven't looked at the code for the FM radio application, and have no
idea about making this existing application work with linux. There is
other source code also for the evaluation board for the chips.

The FM radio stick doesn't appear to demo any RDS/RBDS capability,
at least not where I am, no station or artist/song names are appearing.

  -- Doug

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