1.. SPDX-License-Identifier: GPL-2.0 2 3.. include:: <isonum.txt> 4 5The Silicon Labs Si470x FM Radio Receivers driver 6================================================= 7 8Copyright |copy| 2009 Tobias Lorenz <tobias.lorenz@gmx.net> 9 10 11Information from Silicon Labs 12----------------------------- 13 14Silicon Laboratories is the manufacturer of the radio ICs, that nowadays are the 15most often used radio receivers in cell phones. Usually they are connected with 16I2C. But SiLabs also provides a reference design, which integrates this IC, 17together with a small microcontroller C8051F321, to form a USB radio. 18Part of this reference design is also a radio application in binary and source 19code. The software also contains an automatic firmware upgrade to the most 20current version. Information on these can be downloaded here: 21http://www.silabs.com/usbradio 22 23 24Supported ICs 25------------- 26 27The following ICs have a very similar register set, so that they are or will be 28supported somewhen by the driver: 29 30- Si4700: FM radio receiver 31- Si4701: FM radio receiver, RDS Support 32- Si4702: FM radio receiver 33- Si4703: FM radio receiver, RDS Support 34- Si4704: FM radio receiver, no external antenna required 35- Si4705: FM radio receiver, no external antenna required, RDS support, Dig I/O 36- Si4706: Enhanced FM RDS/TMC radio receiver, no external antenna required, RDS 37 Support 38- Si4707: Dedicated weather band radio receiver with SAME decoder, RDS Support 39- Si4708: Smallest FM receivers 40- Si4709: Smallest FM receivers, RDS Support 41 42More information on these can be downloaded here: 43http://www.silabs.com/products/mcu/Pages/USBFMRadioRD.aspx 44 45 46Supported USB devices 47--------------------- 48 49Currently the following USB radios (vendor:product) with the Silicon Labs si470x 50chips are known to work: 51 52- 10c4:818a: Silicon Labs USB FM Radio Reference Design 53- 06e1:a155: ADS/Tech FM Radio Receiver (formerly Instant FM Music) (RDX-155-EF) 54- 1b80:d700: KWorld USB FM Radio SnapMusic Mobile 700 (FM700) 55- 10c5:819a: Sanei Electric, Inc. FM USB Radio (sold as DealExtreme.com PCear) 56 57 58Software 59-------- 60 61Testing is usually done with most application under Debian/testing: 62 63- fmtools - Utility for managing FM tuner cards 64- gnomeradio - FM-radio tuner for the GNOME desktop 65- gradio - GTK FM radio tuner 66- kradio - Comfortable Radio Application for KDE 67- radio - ncurses-based radio application 68- mplayer - The Ultimate Movie Player For Linux 69- v4l2-ctl - Collection of command line video4linux utilities 70 71For example, you can use: 72 73.. code-block:: none 74 75 v4l2-ctl -d /dev/radio0 --set-ctrl=volume=10,mute=0 --set-freq=95.21 --all 76 77There is also a library libv4l, which can be used. It's going to have a function 78for frequency seeking, either by using hardware functionality as in radio-si470x 79or by implementing a function as we currently have in every of the mentioned 80programs. Somewhen the radio programs should make use of libv4l. 81 82For processing RDS information, there is a project ongoing at: 83http://rdsd.berlios.de/ 84 85There is currently no project for making TMC sentences human readable. 86 87 88Audio Listing 89------------- 90 91USB Audio is provided by the ALSA snd_usb_audio module. It is recommended to 92also select SND_USB_AUDIO, as this is required to get sound from the radio. For 93listing you have to redirect the sound, for example using one of the following 94commands. Please adjust the audio devices to your needs (/dev/dsp* and hw:x,x). 95 96If you just want to test audio (very poor quality): 97 98.. code-block:: none 99 100 cat /dev/dsp1 > /dev/dsp 101 102If you use sox + OSS try: 103 104.. code-block:: none 105 106 sox -2 --endian little -r 96000 -t oss /dev/dsp1 -t oss /dev/dsp 107 108or using sox + alsa: 109 110.. code-block:: none 111 112 sox --endian little -c 2 -S -r 96000 -t alsa hw:1 -t alsa -r 96000 hw:0 113 114If you use arts try: 115 116.. code-block:: none 117 118 arecord -D hw:1,0 -r96000 -c2 -f S16_LE | artsdsp aplay -B - 119 120If you use mplayer try: 121 122.. code-block:: none 123 124 mplayer -radio adevice=hw=1.0:arate=96000 \ 125 -rawaudio rate=96000 \ 126 radio://<frequency>/capture 127 128Module Parameters 129----------------- 130 131After loading the module, you still have access to some of them in the sysfs 132mount under /sys/module/radio_si470x/parameters. The contents of read-only files 133(0444) are not updated, even if space, band and de are changed using private 134video controls. The others are runtime changeable. 135 136 137Errors 138------ 139 140Increase tune_timeout, if you often get -EIO errors. 141 142When timed out or band limit is reached, hw_freq_seek returns -EAGAIN. 143 144If you get any errors from snd_usb_audio, please report them to the ALSA people. 145 146 147Open Issues 148----------- 149 150V4L minor device allocation and parameter setting is not perfect. A solution is 151currently under discussion. 152 153There is an USB interface for downloading/uploading new firmware images. Support 154for it can be implemented using the request_firmware interface. 155 156There is a RDS interrupt mode. The driver is already using the same interface 157for polling RDS information, but is currently not using the interrupt mode. 158 159There is a LED interface, which can be used to override the LED control 160programmed in the firmware. This can be made available using the LED support 161functions in the kernel. 162 163 164Other useful information and links 165---------------------------------- 166 167http://www.silabs.com/usbradio 168