On Friday 24 July 2009 18:37:28 Eduardo Valentin wrote:
> This patch adds a document file for si4713 device driver.
> It describes the driver interfaces and organization.
>
> Signed-off-by: Eduardo Valentin <eduardo.valentin@xxxxxxxxx>
> ---
> linux/Documentation/video4linux/si4713.txt | 175 ++++++++++++++++++++++++++++
> 1 files changed, 175 insertions(+), 0 deletions(-)
> create mode 100644 linux/Documentation/video4linux/si4713.txt
>
> diff --git a/linux/Documentation/video4linux/si4713.txt b/linux/Documentation/video4linux/si4713.txt
> new file mode 100644
> index 0000000..3843af5
> --- /dev/null
> +++ b/linux/Documentation/video4linux/si4713.txt
> @@ -0,0 +1,175 @@
> +Driver for I2C radios for the Silicon Labs Si4713 FM Radio Transmitters
> +
> +Copyright (c) 2009 Nokia Corporation
> +Contact: Eduardo Valentin <eduardo.valentin@xxxxxxxxx>
> +
> +
> +Information about the Device
> +============================
> +This chip is a Silicon Labs product. It is a I2C device, currently on 0Ã?63 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: 1545600 (96.600000 MHz)
> +Video Standard = 0x00000000
> +Modulator:
> + Name : FM Modulator
> + Capabilities : 62.5 Hz stereo rds
> + Frequency range : 76.0 MHz - 108.0 MHz
> + Available subchannels: mono rds
> +
> +User Controls
> +
> + mute (bool) : default=1 value=0
> +
> +FM Radio Modulator Controls
> +
> + 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) : value='Si4713 ' len=1024
> +' len=1024 rds_radio_text (str) : value='Si4713
This doesn't look right. I think this output is from an old v4l2-ctl version.
I'd like to see this output anyway using the latest v4l2-ctl version as I
haven't been able to test it myself.
Based on this output it also looks as if the rds_radio_text string has a \r
at the end. If so, is it supposed to be there?
Regards,
Hans
> + 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=1020 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=120 flags=slider
> + tune_antenna_capacitor (int) : min=0 max=191 step=1 default=0 value=112 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 v4l2-spec 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"
> +
--
Hans Verkuil - video4linux developer - sponsored by TANDBERG Telecom
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