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RADIO(4) Device Drivers Manual RADIO(4)

radiodevice-independent radio driver layer

radio* at bktr?
radio* at fms?
radio* at udsbr?

#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/radioio.h>

The radio driver provides support for various FM radio cards. It provides an uniform programming interface layer above different underlying radio hardware drivers.

For radio tuner controlling there is a single device file available: /dev/radio.

The following ioctl(2) commands are supported:

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.
struct radio_info
struct radio_info
Get or set the current hardware device information into the radio_info structure.
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_SET_MONO		(1<<2)
#define RADIO_CAPS_HW_SEARCH		(1<<3)
#define RADIO_CAPS_HW_AFC		(1<<4)
#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;

The mute field is a boolean.

The volume field holds the card volume information and can be at most 255.

The stereo field is a boolean.

The rfreq holds information about the card reference frequency (not all cards support this feature).

The lock field holds information about the card locking field strength during an automatic search for cards that support this feature.

The freq field is the frequency in kHz the card is tuned to.

The tuner_mode field is the current tuning mode of the tuner. Valid modes are:

The tuner operates in FM radio mode.
The tuner operates in TV mode.

The caps field is read-only and describes the card capabilities. The capabilities can have the following values:

The device can determine if it is tuned to a stereo signal.
The device can determine if it is tuned or not.
The device is capable of forcibly setting its output to mono.
The device can do hardware search.
The device has an internal hardware automatic frequency control.
The device allows changing the reference frequency of a received signal.
The device allows changing the station lock sensitivity used during search operation.
Some cards have several different incarnations. This allows the variant of the card to be determined. Currently not used.

The info field is read-only and describes the current state of the card - tuned/not tuned, stereo signal/mono signal.

Informs whether the device receives a stereo or mono signal.
Informs whether the device receives a valid signal or noise.

The chan holds the TV channel the card is tuned to.

The 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:

U.S.A. Broadcast
U.S.A. Cable IRC
U.S.A. Cable HRC
Western Europe
Japan Broadcast
Japan Cable
Former U.S.S.R. and C.I.S. Countries

Either freq or chan can be used to tune to FM radio stations or TV channels, respectively. Some devices may not support both functionalities.

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 fms(4) cards.


radioctl(1), ioctl(2), bktr(4), fms(4), intro(4), udsbr(4), radio(9)

The radio device driver appeared in OpenBSD 3.0.

The radio driver was written by Vladimir Popov <> and Maxim Tsyplakov <>. The man page was written by Vladimir Popov <>.

September 12, 2017 OpenBSD-6.2