| Driver for USB radios for the Silicon Labs Si470x FM Radio Receivers |
| |
| Copyright (c) 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 |
| |
| 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): |
| cat /dev/dsp1 > /dev/dsp |
| |
| If you use OSS try: |
| sox -2 --endian little -r 96000 -t oss /dev/dsp1 -t oss /dev/dsp |
| |
| If you use arts try: |
| arecord -D hw:1,0 -r96000 -c2 -f S16_LE | artsdsp aplay -B - |
| |
| If you use mplayer try: |
| 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 |
