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 57There is also a library libv4l, which can be used. It's going to have a function 58for frequency seeking, either by using hardware functionality as in radio-si470x 59or by implementing a function as we currently have in every of the mentioned 60programs. Somewhen the radio programs should make use of libv4l. 61 62For processing RDS information, there is a project ongoing at: 63http://rdsd.berlios.de/ 64 65There is currently no project for making TMC sentences human readable. 66 67 68Audio Listing 69============= 70USB Audio is provided by the ALSA snd_usb_audio module. It is recommended to 71also select SND_USB_AUDIO, as this is required to get sound from the radio. For 72listing you have to redirect the sound, for example using one of the following 73commands. Please adjust the audio devices to your needs (/dev/dsp* and hw:x,x). 74 75If you just want to test audio (very poor quality): 76cat /dev/dsp1 > /dev/dsp 77 78If you use OSS try: 79sox -2 --endian little -r 96000 -t oss /dev/dsp1 -t oss /dev/dsp 80 81If you use arts try: 82arecord -D hw:1,0 -r96000 -c2 -f S16_LE | artsdsp aplay -B - 83 84If you use mplayer try: 85mplayer -radio adevice=hw=1.0:arate=96000 \ 86 -rawaudio rate=96000 \ 87 radio://<frequency>/capture 88 89Module Parameters 90================= 91After loading the module, you still have access to some of them in the sysfs 92mount under /sys/module/radio_si470x/parameters. The contents of read-only files 93(0444) are not updated, even if space, band and de are changed using private 94video controls. The others are runtime changeable. 95 96 97Errors 98====== 99Increase tune_timeout, if you often get -EIO errors. 100 101When timed out or band limit is reached, hw_freq_seek returns -EAGAIN. 102 103If you get any errors from snd_usb_audio, please report them to the ALSA people. 104 105 106Open Issues 107=========== 108V4L minor device allocation and parameter setting is not perfect. A solution is 109currently under discussion. 110 111There is an USB interface for downloading/uploading new firmware images. Support 112for it can be implemented using the request_firmware interface. 113 114There is a RDS interrupt mode. The driver is already using the same interface 115for polling RDS information, but is currently not using the interrupt mode. 116 117There is a LED interface, which can be used to override the LED control 118programmed in the firmware. This can be made available using the LED support 119functions in the kernel. 120 121 122Other useful information and links 123================================== 124http://www.silabs.com/usbradio 125