Re: Controlling and reading a usb radio

[Chuck C. <cm...@ea...>]

The chip that is being controlled is by SIlicaon labs
http://www.silabs.com/pages/Silabs-Search.aspx?q=si470x

On 05/13/2012 12:01 PM, Deron wrote:
> On 5/12/12 10:57 PM, Hans de Goede wrote:
>>> "radio" appears to get a little further along. It actual seems to
>>> enable the radio in so much as when it is running, I get what seems
>>> like real radio static as to the just near silence I get otherwise.
>>> But I don't get any change in the output no matter the frequency tuned.
>>>
>>
>> Ok, good, looking in:
>> drivers/media/radio/si470x/radio-si470x-common.c
>>
>> I see the following module parameters:
>> /* Spacing (kHz) */
>> /* 0: 200 kHz (USA, Australia) */
>> /* 1: 100 kHz (Europe, Japan) */
>> /* 2:  50 kHz */
>> static unsigned short space = 2;
>> module_param(space, ushort, 0444);
>> MODULE_PARM_DESC(space, "Spacing: 0=200kHz 1=100kHz *2=50kHz*");
>>
>> /* Bottom of Band (MHz) */
>> /* 0: 87.5 - 108 MHz (USA, Europe)*/
>> /* 1: 76   - 108 MHz (Japan wide band) */
>> /* 2: 76   -  90 MHz (Japan) */
>> static unsigned short band = 1;
>> module_param(band, ushort, 0444);
>> MODULE_PARM_DESC(band, "Band: 0=87.5..108MHz *1=76..108MHz*
>> 2=76..90MHz");
>>
>> /* De-emphasis */
>> /* 0: 75 us (USA) */
>> /* 1: 50 us (Europe, Australia, Japan) */
>> static unsigned short de = 1;
>> module_param(de, ushort, 0444);
>> MODULE_PARM_DESC(de, "De-emphasis: 0=75us *1=50us*");
>>
>> /* Tune timeout */
>> static unsigned int tune_timeout = 3000;
>> module_param(tune_timeout, uint, 0644);
>> MODULE_PARM_DESC(tune_timeout, "Tune timeout: *3000*");
>>
>> /* Seek timeout */
>> static unsigned int seek_timeout = 5000;
>> module_param(seek_timeout, uint, 0644);
>> MODULE_PARM_DESC(seek_timeout, "Seek timeout: *5000*");
>>
>> Especially the band parameter looks interesting, as
>> according to your commented usb dumps your device has a
>> bottom of 87.5 Mhz, were the driver defaults to 76 Mhz,
>> so if you tuned to a known to work station in radio,
>> you actually didn't because of this setting being wrong,
>> edit /etc/modprobe.d/radio.conf
>>
>> And put the following there:
>> options radio-usb-si470x band=0
>>
>> Then do:
>> rmmod radio-usb-si470x
>> modprobe radio-usb-si470x
>>
>> And redo the driver binding, now tune to a radio station
>> you know to work (from testing in windows for example)
>> using radio, and hopefully things will work then.
>>
>
> I was so hopeful! However, it made no difference. I even then tried
> setting space=0 and de=0, to no avail.
>
> My attempts at a custom frequency changing program will generate pops in
> the audio output when changing the frequency, but the audio is silent.
> The radio program
> (http://www.cs.fsu.edu/~baker/devices/lxr/http/source/xawtv-3.95/console/radio.c)
> seems to enable the radio as when it is started the audio goes from
> silent to static, but I get the error "VIDIOCGAUDIO: Invalid argument"
> twice to console and changing the frequency does not generate any change
> in audio output. No pop, no change to static.
>
>
> Thanks!
>
> Deron
>
>
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