166 lines
5.1 KiB
ReStructuredText
166 lines
5.1 KiB
ReStructuredText
.. include:: <isonum.txt>
|
|
|
|
The Silicon Labs Si470x FM Radio Receivers driver
|
|
=================================================
|
|
|
|
Copyright |copy| 2009 Tobias Lorenz <tobias.lorenz@gmx.net>
|
|
|
|
|
|
Information from Silicon Labs
|
|
-----------------------------
|
|
|
|
Silicon Laboratories is the manufacturer of the radio ICs, that nowadays are the
|
|
most often used radio receivers in cell phones. Usually they are connected with
|
|
I2C. But SiLabs also provides a reference design, which integrates this IC,
|
|
together with a small microcontroller C8051F321, to form a USB radio.
|
|
Part of this reference design is also a radio application in binary and source
|
|
code. The software also contains an automatic firmware upgrade to the most
|
|
current version. Information on these can be downloaded here:
|
|
http://www.silabs.com/usbradio
|
|
|
|
|
|
Supported ICs
|
|
-------------
|
|
|
|
The following ICs have a very similar register set, so that they are or will be
|
|
supported somewhen by the driver:
|
|
|
|
- Si4700: FM radio receiver
|
|
- Si4701: FM radio receiver, RDS Support
|
|
- Si4702: FM radio receiver
|
|
- Si4703: FM radio receiver, RDS Support
|
|
- Si4704: FM radio receiver, no external antenna required
|
|
- Si4705: FM radio receiver, no external antenna required, RDS support, Dig I/O
|
|
- Si4706: Enhanced FM RDS/TMC radio receiver, no external antenna required, RDS
|
|
Support
|
|
- Si4707: Dedicated weather band radio receiver with SAME decoder, RDS Support
|
|
- Si4708: Smallest FM receivers
|
|
- Si4709: Smallest FM receivers, RDS Support
|
|
|
|
More information on these can be downloaded here:
|
|
http://www.silabs.com/products/mcu/Pages/USBFMRadioRD.aspx
|
|
|
|
|
|
Supported USB devices
|
|
---------------------
|
|
|
|
Currently the following USB radios (vendor:product) with the Silicon Labs si470x
|
|
chips are known to work:
|
|
|
|
- 10c4:818a: Silicon Labs USB FM Radio Reference Design
|
|
- 06e1:a155: ADS/Tech FM Radio Receiver (formerly Instant FM Music) (RDX-155-EF)
|
|
- 1b80:d700: KWorld USB FM Radio SnapMusic Mobile 700 (FM700)
|
|
- 10c5:819a: Sanei Electric, Inc. FM USB Radio (sold as DealExtreme.com PCear)
|
|
|
|
|
|
Software
|
|
--------
|
|
|
|
Testing is usually done with most application under Debian/testing:
|
|
|
|
- fmtools - Utility for managing FM tuner cards
|
|
- gnomeradio - FM-radio tuner for the GNOME desktop
|
|
- gradio - GTK FM radio tuner
|
|
- kradio - Comfortable Radio Application for KDE
|
|
- radio - ncurses-based radio application
|
|
- mplayer - The Ultimate Movie Player For Linux
|
|
- v4l2-ctl - Collection of command line video4linux utilities
|
|
|
|
For example, you can use:
|
|
|
|
.. code-block:: none
|
|
|
|
v4l2-ctl -d /dev/radio0 --set-ctrl=volume=10,mute=0 --set-freq=95.21 --all
|
|
|
|
There is also a library libv4l, which can be used. It's going to have a function
|
|
for frequency seeking, either by using hardware functionality as in radio-si470x
|
|
or by implementing a function as we currently have in every of the mentioned
|
|
programs. Somewhen the radio programs should make use of libv4l.
|
|
|
|
For processing RDS information, there is a project ongoing at:
|
|
http://rdsd.berlios.de/
|
|
|
|
There is currently no project for making TMC sentences human readable.
|
|
|
|
|
|
Audio Listing
|
|
-------------
|
|
|
|
USB Audio is provided by the ALSA snd_usb_audio module. It is recommended to
|
|
also select SND_USB_AUDIO, as this is required to get sound from the radio. For
|
|
listing you have to redirect the sound, for example using one of the following
|
|
commands. Please adjust the audio devices to your needs (/dev/dsp* and hw:x,x).
|
|
|
|
If you just want to test audio (very poor quality):
|
|
|
|
.. code-block:: none
|
|
|
|
cat /dev/dsp1 > /dev/dsp
|
|
|
|
If you use sox + OSS try:
|
|
|
|
.. code-block:: none
|
|
|
|
sox -2 --endian little -r 96000 -t oss /dev/dsp1 -t oss /dev/dsp
|
|
|
|
or using sox + alsa:
|
|
|
|
.. code-block:: none
|
|
|
|
sox --endian little -c 2 -S -r 96000 -t alsa hw:1 -t alsa -r 96000 hw:0
|
|
|
|
If you use arts try:
|
|
|
|
.. code-block:: none
|
|
|
|
arecord -D hw:1,0 -r96000 -c2 -f S16_LE | artsdsp aplay -B -
|
|
|
|
If you use mplayer try:
|
|
|
|
.. code-block:: none
|
|
|
|
mplayer -radio adevice=hw=1.0:arate=96000 \
|
|
-rawaudio rate=96000 \
|
|
radio://<frequency>/capture
|
|
|
|
Module Parameters
|
|
-----------------
|
|
|
|
After loading the module, you still have access to some of them in the sysfs
|
|
mount under /sys/module/radio_si470x/parameters. The contents of read-only files
|
|
(0444) are not updated, even if space, band and de are changed using private
|
|
video controls. The others are runtime changeable.
|
|
|
|
|
|
Errors
|
|
------
|
|
|
|
Increase tune_timeout, if you often get -EIO errors.
|
|
|
|
When timed out or band limit is reached, hw_freq_seek returns -EAGAIN.
|
|
|
|
If you get any errors from snd_usb_audio, please report them to the ALSA people.
|
|
|
|
|
|
Open Issues
|
|
-----------
|
|
|
|
V4L minor device allocation and parameter setting is not perfect. A solution is
|
|
currently under discussion.
|
|
|
|
There is an USB interface for downloading/uploading new firmware images. Support
|
|
for it can be implemented using the request_firmware interface.
|
|
|
|
There is a RDS interrupt mode. The driver is already using the same interface
|
|
for polling RDS information, but is currently not using the interrupt mode.
|
|
|
|
There is a LED interface, which can be used to override the LED control
|
|
programmed in the firmware. This can be made available using the LED support
|
|
functions in the kernel.
|
|
|
|
|
|
Other useful information and links
|
|
----------------------------------
|
|
|
|
http://www.silabs.com/usbradio
|