.\"	$RuOBSD: radio.4,v 1.4 2001/10/26 05:38:43 form Exp $
.\"	$OpenBSD: radio.4,v 1.32 2021/02/01 07:09:37 jmc Exp $
.\"
.\" Copyright (c) 2001 Vladimir Popov
.\" All rights reserved.
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.Dd $Mdocdate: February 1 2021 $
.Dt RADIO 4
.Os
.Sh NAME
.Nm radio
.Nd device-independent radio driver layer
.Sh SYNOPSIS
.Cd "radio* at bktr?"
.Cd "radio* at fms?"
.Cd "radio* at udsbr?"
.Pp
.In sys/types.h
.In sys/ioctl.h
.In sys/radioio.h
.Sh DESCRIPTION
The
.Nm
driver provides support for various FM radio cards.
It provides a uniform programming interface layer above different underlying
radio hardware drivers.
.Pp
For radio tuner controlling there is a single device file available:
.Pa /dev/radio .
.Pp
The following
.Xr ioctl 2
commands are supported:
.Pp
.Bl -tag -width indent -compact
.It Dv RIOCSSRCH Fa int
This command assumes that a signal search is required and gives direction
of search to the driver \- 0 to search down and any non-zero value to search up.
.It Dv RIOCGINFO Fa "struct radio_info"
.It Dv RIOCSINFO Fa "struct radio_info"
Get or set the current hardware device information into the
.Fa radio_info
structure.
.Bd -literal
struct radio_info {
	int	mute;
	int	volume;
	int	stereo;
	int	rfreq;	/* reference frequency */
	int	lock;	/* locking field strength */
	u_int32_t	freq;	/* in kHz */
	u_int32_t	caps;	/* card capabilities */
#define RADIO_CAPS_DETECT_STEREO	(1<<0)
#define RADIO_CAPS_DETECT_SIGNAL	(1<<1)
#define RADIO_CAPS_SET_MONO		(1<<2)
#define RADIO_CAPS_HW_SEARCH		(1<<3)
#define RADIO_CAPS_HW_AFC		(1<<4)
#define RADIO_CAPS_REFERENCE_FREQ	(1<<5)
#define RADIO_CAPS_LOCK_SENSITIVITY	(1<<6)
#define RADIO_CARD_TYPE			(0xFF<<16)
	u_int32_t	info;
#define RADIO_INFO_STEREO		(1<<0)
#define RADIO_INFO_SIGNAL		(1<<1)
	u_int32_t	tuner_mode;
#define RADIO_TUNER_MODE_RADIO		(1<<0)
#define RADIO_TUNER_MODE_TV		(1<<1)
	u_int32_t	chan;
	u_int32_t	chnlset;
};
.Ed
.Pp
The
.Va mute
field is a boolean.
.Pp
The
.Va volume
field holds the card volume information and can be at most 255.
.Pp
The
.Va stereo
field is a boolean.
.Pp
The
.Va rfreq
holds information about the card reference frequency (not all cards support
this feature).
.Pp
The
.Va lock
field holds information about the card locking field strength during
an automatic search for cards that support this feature.
.Pp
The
.Va freq
field is the frequency in kHz the card is tuned to.
.Pp
The
.Va tuner_mode
field is the current tuning mode of the tuner.
Valid modes are:
.Pp
.Bl -tag -width indent -compact
.It Dv RADIO_TUNER_MODE_RADIO
The tuner operates in FM radio mode.
.It Dv RADIO_TUNER_MODE_TV
The tuner operates in TV mode.
.El
.Pp
The
.Va caps
field is read-only and describes the card capabilities.
The capabilities can have the following values:
.Pp
.Bl -tag -width indent -compact
.It Dv RADIO_CAPS_DETECT_STEREO
The device can determine if it is tuned to a stereo signal.
.It Dv RADIO_CAPS_DETECT_SIGNAL
The device can determine if it is tuned or not.
.It Dv RADIO_CAPS_SET_MONO
The device is capable of forcibly setting its output to mono.
.It Dv RADIO_CAPS_HW_SEARCH
The device can do hardware search.
.It Dv RADIO_CAPS_HW_AFC
The device has an internal hardware automatic frequency control.
.It Dv RADIO_CAPS_REFERENCE_FREQ
The device allows changing the reference frequency of a received signal.
.It Dv RADIO_CAPS_LOCK_SENSITIVITY
The device allows changing the station lock sensitivity used during search
operation.
.It Dv RADIO_CARD_TYPE
Some cards have several different incarnations.
This allows the variant of the card to be determined.
Currently not used.
.El
.Pp
The
.Va info
field is read-only and describes the current state of the card \-
tuned/not tuned, stereo signal/mono signal.
.Pp
.Bl -tag -width indent -compact
.It Dv RADIO_INFO_STEREO
Informs whether the device receives a stereo or mono signal.
.It Dv RADIO_INFO_SIGNAL
Informs whether the device receives a valid signal or noise.
.El
.Pp
The
.Va chan
holds the TV channel the card is tuned to.
.Pp
The
.Va chnlset
specifies the TV channel set currently being used.
The tuner uses the current channel set to derive the tuning frequency
from the channel number.
Western Europe is the default channel set.
The following is a list of valid channel sets:
.Pp
.Bl -tag -width indent -compact
.It 1
U.S.A. Broadcast
.It 2
U.S.A. Cable IRC
.It 3
U.S.A. Cable HRC
.It 4
Western Europe
.It 5
Japan Broadcast
.It 6
Japan Cable
.It 7
Former U.S.S.R. and C.I.S. Countries
.It 8
Australia
.It 9
France
.El
.El
.Pp
Either
.Va freq
or
.Va chan
can be used to tune to FM radio stations or TV channels,
respectively.
Some devices may not support both functionalities.
.Sh CHIPSETS
The TEA5757; TEA5759 is a 44-pin integrated AM/FM stereo radio circuit.
The radio part is based on the TEA5712.
The TEA5757 is used in FM-standards in which the local oscillator frequency
is above the radio frequency (e.g. European and American standards).
The TEA5759 is the version in which the oscillator frequency is below
the radio frequency (e.g. Japanese standards).
To conform with the Japanese standards, it is necessary to set the flags' least
significant bit to 1.
The TEA5757; TEA5759 has a 25-bit read-write shift register.
The TEA5757 chips are used in
.Xr fms 4
cards.
.Sh FILES
.Bl -tag -width /dev/radio -compact
.It Pa /dev/radio
.El
.Sh SEE ALSO
.Xr radioctl 1 ,
.Xr ioctl 2 ,
.Xr bktr 4 ,
.Xr fms 4 ,
.Xr intro 4 ,
.Xr udsbr 4 ,
.Xr radio 9
.Sh HISTORY
The
.Nm
device driver appeared in
.Ox 3.0 .
.Sh AUTHORS
.An -nosplit
The
.Nm
driver was written by
.An Vladimir Popov Aq Mt jumbo@narod.ru
and
.An Maxim Tsyplakov Aq Mt tm@oganer.net .
The man page was written by
.An Vladimir Popov Aq Mt jumbo@narod.ru .