RDS/RBDS FM receiver (external) for traffic conditions

Doug Sutherland doug at proficio.ca
Sun Nov 18 20:41:25 CET 2007

Josh wrote:
> I have always thought of HID as using an external device that then 
> communicates to the computer, this is using a virtual app on the 
> computer to control an external device - I don't disagree that it is 
> Human Interface.

Aside from keyboards and mice, this idea is exactly what generic
HID is for. I have seen others that do the same. For example 
audio codec evaluation boards use generic HID communication
and have volume, balance, fader etc controls in a similar PC app.
Interestingly though, generic USB HID can also be used as just a 
simple comminication protocol between host and slave, and can
do pretty decent throughput.

I will look further into this, because I have some of the SI4701
chips here too, my intention was to write my own SPI code on
a different micro, so I haven't looked too closely at their source.
I was thinking about doing something better: using a micro to 
create a virtual com port, using the driverless USB ACM CDC
(communication device class), which would be translated to the
necessary SPI commands on the micro firmware, to control 
the FM tuner and to read and send the RDS/RBDS data.

This way you would have generic USB audio and generic 
USB CDC serial, and you could just open a serial port and
send commands to change stations and such, and the RDS
data would just "arrive" at the serial port.

This assume a different custom small board with SI4701 and
microcontroller, most likely an ARM7.

  -- Doug

  -- Doug

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