Author Topic: FM Radio (fmtools)  (Read 1803 times)

kuwanger (OP)

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FM Radio (fmtools)
« on: January 19, 2014, 07:41:49 pm »
So, as I understand it there's currently already driver FM support for the GCW Zero.  Unfortunately, a quick check with a compile of fmtools, a command-line fm radio, and I get:

Code: [Select]
opendingux:/media/sdcard # ./fmscan
./fmscan: VIDIOC_G_TUNER: No such device or address

Further, an strace reveals...

Code: [Select]
open("/dev/radio0", O_RDONLY)           = 3
ioctl(3, VIDIOC_QUERYCTRL, 0x7ffc3460)  = 0
ioctl(3, VIDIOC_G_TUNER, 0x7ffc34a4)    = -1 ENXIO (No such device or address)

Ie, it's not a permission problem per se.  So, I'm not sure what's up with that.  Under /sys/... I find:

Code: [Select]
opendingux:/sys/devices/virtual/video4linux/radio0 # cat name
RDA5807 FM receiver

And it appears that said device isn't supported under the main kernel tree, but there's xburst cpu rda5807 driver and I presume the code for the gcw zero comes from here or another similar line and a quick skim at least looks like it's generally right in supporting the needed IOCTLs, so I again presume that's not the issue.

I guess what I'm getting at is, um, so does the FM radio actually work and if so what am I doing wrong?  Before going much further in attempting to make some sort of FM Radio GUI, I'd like to at least make sure my FM radio is actually working.  So, any ideas on what to try next?

PS - If this at all matters, this is a black kickstarter gcw zero.


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Re: FM Radio (fmtools)
« Reply #1 on: January 19, 2014, 10:43:21 pm »
We already have fm-tools included in the rootfs, no need to compile your own. For the rest, I'll let mth answer.


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Re: FM Radio (fmtools)
« Reply #2 on: January 20, 2014, 03:08:22 pm »
The FM module is on the same power output as the LCD panel. Unfortunately, the kernel does not know that yet. Therefore, if the LCD panel goes into power saving, power to the FM module is cut as well. So for now, disable the display power saving if you want to play with FM.

Other things you should know:
  • Use the "line in bypass" source in alsamixer to hear the radio.
  • The headphones cable acts as an antenna, so even if you want to listen through the speakers, a headphone has to be inserted to get reception.
  • Indoors reception might be poor; you might have to reduce the threshold for "fmscan" to find any channels.


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