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diff --git a/Documentation/video4linux/si470x.txt b/Documentation/video4linux/si470x.txt new file mode 100644 index 00000000000..11c5fd22a33 --- /dev/null +++ b/Documentation/video4linux/si470x.txt @@ -0,0 +1,118 @@ +Driver for USB radios for the Silicon Labs Si470x FM Radio Receivers + +Copyright (c) 2008 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) + + +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 + +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. + +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 - + + +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 |