57f902d0f3
It was really confusing to have media-specs, v4l2-spec and dvb-spec. So this patch removes v4l2-spec and dvb-spec. The docs in dvb-spec and the V4L1_API.html file were moved to media-specs/old-docs. Removed all references to v4l2-spec and dvb-spec. Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
176 lines
6.5 KiB
Text
176 lines
6.5 KiB
Text
Driver for I2C radios for the Silicon Labs Si4713 FM Radio Transmitters
|
|
|
|
Copyright (c) 2009 Nokia Corporation
|
|
Contact: Eduardo Valentin <eduardo.valentin@nokia.com>
|
|
|
|
|
|
Information about the Device
|
|
============================
|
|
This chip is a Silicon Labs product. It is a I2C device, currently on 0x63 address.
|
|
Basically, it has transmission and signal noise level measurement features.
|
|
|
|
The Si4713 integrates transmit functions for FM broadcast stereo transmission.
|
|
The chip also allows integrated receive power scanning to identify low signal
|
|
power FM channels.
|
|
|
|
The chip is programmed using commands and responses. There are also several
|
|
properties which can change the behavior of this chip.
|
|
|
|
Users must comply with local regulations on radio frequency (RF) transmission.
|
|
|
|
Device driver description
|
|
=========================
|
|
There are two modules to handle this device. One is a I2C device driver
|
|
and the other is a platform driver.
|
|
|
|
The I2C device driver exports a v4l2-subdev interface to the kernel.
|
|
All properties can also be accessed by v4l2 extended controls interface, by
|
|
using the v4l2-subdev calls (g_ext_ctrls, s_ext_ctrls).
|
|
|
|
The platform device driver exports a v4l2 radio device interface to user land.
|
|
So, it uses the I2C device driver as a sub device in order to send the user
|
|
commands to the actual device. Basically it is a wrapper to the I2C device driver.
|
|
|
|
Applications can use v4l2 radio API to specify frequency of operation, mute state,
|
|
etc. But mostly of its properties will be present in the extended controls.
|
|
|
|
When the v4l2 mute property is set to 1 (true), the driver will turn the chip off.
|
|
|
|
Properties description
|
|
======================
|
|
|
|
The properties can be accessed using v4l2 extended controls.
|
|
Here is an output from v4l2-ctl util:
|
|
/ # v4l2-ctl -d /dev/radio0 --all -L
|
|
Driver Info:
|
|
Driver name : radio-si4713
|
|
Card type : Silicon Labs Si4713 Modulator
|
|
Bus info :
|
|
Driver version: 0
|
|
Capabilities : 0x00080800
|
|
RDS Output
|
|
Modulator
|
|
Audio output: 0 (FM Modulator Audio Out)
|
|
Frequency: 1408000 (88.000000 MHz)
|
|
Video Standard = 0x00000000
|
|
Modulator:
|
|
Name : FM Modulator
|
|
Capabilities : 62.5 Hz stereo rds
|
|
Frequency range : 76.0 MHz - 108.0 MHz
|
|
Subchannel modulation: stereo+rds
|
|
|
|
User Controls
|
|
|
|
mute (bool) : default=1 value=0
|
|
|
|
FM Radio Modulator Controls
|
|
|
|
rds_signal_deviation (int) : min=0 max=90000 step=10 default=200 value=200 flags=slider
|
|
rds_program_id (int) : min=0 max=65535 step=1 default=0 value=0
|
|
rds_program_type (int) : min=0 max=31 step=1 default=0 value=0
|
|
rds_ps_name (str) : min=0 max=96 step=8 value='si4713 '
|
|
rds_radio_text (str) : min=0 max=384 step=32 value=''
|
|
audio_limiter_feature_enabled (bool) : default=1 value=1
|
|
audio_limiter_release_time (int) : min=250 max=102390 step=50 default=5010 value=5010 flags=slider
|
|
audio_limiter_deviation (int) : min=0 max=90000 step=10 default=66250 value=66250 flags=slider
|
|
audio_compression_feature_enabl (bool) : default=1 value=1
|
|
audio_compression_gain (int) : min=0 max=20 step=1 default=15 value=15 flags=slider
|
|
audio_compression_threshold (int) : min=-40 max=0 step=1 default=-40 value=-40 flags=slider
|
|
audio_compression_attack_time (int) : min=0 max=5000 step=500 default=0 value=0 flags=slider
|
|
audio_compression_release_time (int) : min=100000 max=1000000 step=100000 default=1000000 value=1000000 flags=slider
|
|
pilot_tone_feature_enabled (bool) : default=1 value=1
|
|
pilot_tone_deviation (int) : min=0 max=90000 step=10 default=6750 value=6750 flags=slider
|
|
pilot_tone_frequency (int) : min=0 max=19000 step=1 default=19000 value=19000 flags=slider
|
|
pre_emphasis_settings (menu) : min=0 max=2 default=1 value=1
|
|
tune_power_level (int) : min=0 max=120 step=1 default=88 value=88 flags=slider
|
|
tune_antenna_capacitor (int) : min=0 max=191 step=1 default=0 value=110 flags=slider
|
|
/ #
|
|
|
|
Here is a summary of them:
|
|
|
|
* Pilot is an audible tone sent by the device.
|
|
|
|
pilot_frequency - Configures the frequency of the stereo pilot tone.
|
|
pilot_deviation - Configures pilot tone frequency deviation level.
|
|
pilot_enabled - Enables or disables the pilot tone feature.
|
|
|
|
* The si4713 device is capable of applying audio compression to the transmitted signal.
|
|
|
|
acomp_enabled - Enables or disables the audio dynamic range control feature.
|
|
acomp_gain - Sets the gain for audio dynamic range control.
|
|
acomp_threshold - Sets the threshold level for audio dynamic range control.
|
|
acomp_attack_time - Sets the attack time for audio dynamic range control.
|
|
acomp_release_time - Sets the release time for audio dynamic range control.
|
|
|
|
* Limiter setups audio deviation limiter feature. Once a over deviation occurs,
|
|
it is possible to adjust the front-end gain of the audio input and always
|
|
prevent over deviation.
|
|
|
|
limiter_enabled - Enables or disables the limiter feature.
|
|
limiter_deviation - Configures audio frequency deviation level.
|
|
limiter_release_time - Sets the limiter release time.
|
|
|
|
* Tuning power
|
|
|
|
power_level - Sets the output power level for signal transmission.
|
|
antenna_capacitor - This selects the value of antenna tuning capacitor manually
|
|
or automatically if set to zero.
|
|
|
|
* RDS related
|
|
|
|
rds_ps_name - Sets the RDS ps name field for transmission.
|
|
rds_radio_text - Sets the RDS radio text for transmission.
|
|
rds_pi - Sets the RDS PI field for transmission.
|
|
rds_pty - Sets the RDS PTY field for transmission.
|
|
|
|
* Region related
|
|
|
|
preemphasis - sets the preemphasis to be applied for transmission.
|
|
|
|
RNL
|
|
===
|
|
|
|
This device also has an interface to measure received noise level. To do that, you should
|
|
ioctl the device node. Here is an code of example:
|
|
|
|
int main (int argc, char *argv[])
|
|
{
|
|
struct si4713_rnl rnl;
|
|
int fd = open("/dev/radio0", O_RDWR);
|
|
int rval;
|
|
|
|
if (argc < 2)
|
|
return -EINVAL;
|
|
|
|
if (fd < 0)
|
|
return fd;
|
|
|
|
sscanf(argv[1], "%d", &rnl.frequency);
|
|
|
|
rval = ioctl(fd, SI4713_IOC_MEASURE_RNL, &rnl);
|
|
if (rval < 0)
|
|
return rval;
|
|
|
|
printf("received noise level: %d\n", rnl.rnl);
|
|
|
|
close(fd);
|
|
}
|
|
|
|
The struct si4713_rnl and SI4713_IOC_MEASURE_RNL are defined under
|
|
include/media/si4713.h.
|
|
|
|
Stereo/Mono and RDS subchannels
|
|
===============================
|
|
|
|
The device can also be configured using the available sub channels for
|
|
transmission. To do that use S/G_MODULATOR ioctl and configure txsubchans properly.
|
|
Refer to the V4L2 API specification for proper use of this ioctl.
|
|
|
|
Testing
|
|
=======
|
|
Testing is usually done with v4l2-ctl utility for managing FM tuner cards.
|
|
The tool can be found in v4l-dvb repository under v4l2-apps/util directory.
|
|
|
|
Example for setting rds ps name:
|
|
# v4l2-ctl -d /dev/radio0 --set-ctrl=rds_ps_name="Dummy"
|
|
|