1Driver for USB radios for the Silicon Labs Si470x FM Radio Receivers 2 3Copyright (c) 2009 Tobias Lorenz <tobias.lorenz@gmx.net> 4 5 6Information from Silicon Labs 7============================= 8Silicon Laboratories is the manufacturer of the radio ICs, that nowadays are the 9most often used radio receivers in cell phones. Usually they are connected with 10I2C. But SiLabs also provides a reference design, which integrates this IC, 11together with a small microcontroller C8051F321, to form a USB radio. 12Part of this reference design is also a radio application in binary and source 13code. The software also contains an automatic firmware upgrade to the most 14current version. Information on these can be downloaded here: 15http://www.silabs.com/usbradio 16 17 18Supported ICs 19============= 20The following ICs have a very similar register set, so that they are or will be 21supported somewhen by the driver: 22- Si4700: FM radio receiver 23- Si4701: FM radio receiver, RDS Support 24- Si4702: FM radio receiver 25- Si4703: FM radio receiver, RDS Support 26- Si4704: FM radio receiver, no external antenna required 27- Si4705: FM radio receiver, no external antenna required, RDS support, Dig I/O 28- Si4706: Enhanced FM RDS/TMC radio receiver, no external antenna required, RDS 29 Support 30- Si4707: Dedicated weather band radio receiver with SAME decoder, RDS Support 31- Si4708: Smallest FM receivers 32- Si4709: Smallest FM receivers, RDS Support 33More information on these can be downloaded here: 34http://www.silabs.com/products/mcu/Pages/USBFMRadioRD.aspx 35 36 37Supported USB devices 38===================== 39Currently the following USB radios (vendor:product) with the Silicon Labs si470x 40chips are known to work: 41- 10c4:818a: Silicon Labs USB FM Radio Reference Design 42- 06e1:a155: ADS/Tech FM Radio Receiver (formerly Instant FM Music) (RDX-155-EF) 43- 1b80:d700: KWorld USB FM Radio SnapMusic Mobile 700 (FM700) 44- 10c5:819a: Sanei Electric, Inc. FM USB Radio (sold as DealExtreme.com PCear) 45 46 47Software 48======== 49Testing is usually done with most application under Debian/testing: 50- fmtools - Utility for managing FM tuner cards 51- gnomeradio - FM-radio tuner for the GNOME desktop 52- gradio - GTK FM radio tuner 53- kradio - Comfortable Radio Application for KDE 54- radio - ncurses-based radio application 55- mplayer - The Ultimate Movie Player For Linux 56- v4l2-ctl - Collection of command line video4linux utilities 57For example, you can use: 58v4l2-ctl -d /dev/radio0 --set-ctrl=volume=10,mute=0 --set-freq=95.21 --all 59 60There is also a library libv4l, which can be used. It's going to have a function 61for frequency seeking, either by using hardware functionality as in radio-si470x 62or by implementing a function as we currently have in every of the mentioned 63programs. Somewhen the radio programs should make use of libv4l. 64 65For processing RDS information, there is a project ongoing at: 66http://rdsd.berlios.de/ 67 68There is currently no project for making TMC sentences human readable. 69 70 71Audio Listing 72============= 73USB Audio is provided by the ALSA snd_usb_audio module. It is recommended to 74also select SND_USB_AUDIO, as this is required to get sound from the radio. For 75listing you have to redirect the sound, for example using one of the following 76commands. Please adjust the audio devices to your needs (/dev/dsp* and hw:x,x). 77 78If you just want to test audio (very poor quality): 79cat /dev/dsp1 > /dev/dsp 80 81If you use sox + OSS try: 82sox -2 --endian little -r 96000 -t oss /dev/dsp1 -t oss /dev/dsp 83or using sox + alsa: 84sox --endian little -c 2 -S -r 96000 -t alsa hw:1 -t alsa -r 96000 hw:0 85 86If you use arts try: 87arecord -D hw:1,0 -r96000 -c2 -f S16_LE | artsdsp aplay -B - 88 89If you use mplayer try: 90mplayer -radio adevice=hw=1.0:arate=96000 \ 91 -rawaudio rate=96000 \ 92 radio://<frequency>/capture 93 94Module Parameters 95================= 96After loading the module, you still have access to some of them in the sysfs 97mount under /sys/module/radio_si470x/parameters. The contents of read-only files 98(0444) are not updated, even if space, band and de are changed using private 99video controls. The others are runtime changeable. 100 101 102Errors 103====== 104Increase tune_timeout, if you often get -EIO errors. 105 106When timed out or band limit is reached, hw_freq_seek returns -EAGAIN. 107 108If you get any errors from snd_usb_audio, please report them to the ALSA people. 109 110 111Open Issues 112=========== 113V4L minor device allocation and parameter setting is not perfect. A solution is 114currently under discussion. 115 116There is an USB interface for downloading/uploading new firmware images. Support 117for it can be implemented using the request_firmware interface. 118 119There is a RDS interrupt mode. The driver is already using the same interface 120for polling RDS information, but is currently not using the interrupt mode. 121 122There is a LED interface, which can be used to override the LED control 123programmed in the firmware. This can be made available using the LED support 124functions in the kernel. 125 126 127Other useful information and links 128================================== 129http://www.silabs.com/usbradio 130