NAME
guspnp —
Am78C201 audio device
driver
SYNOPSIS
guspnp* at isapnp?
audio* at audiobus?
There should be no limit caused by the driver on the number of drivers or cards
active in the system.
DESCRIPTION
The
guspnp driver provides support for audio subsystems using
the Interwave (Am78C20x) family of ICs, usually the Gravis Ultrasound Plug and
Play. Unlike the
gus driver guspnp driver does not require
any local memory for the IC, but uses the codec for both playback and
recording. The
guspnp driver can simultaneously playback and
record 8- and 16-bit samples at frequencies from 5.51kHz to 48kHz.
The
guspnp driver relies on
isapnp to
allocate suitable resources for it. This version of the driver only uses the
first logical device of the five the Interwave IC has. The four unused logical
devices are the ATAPI CD-ROM device, PnP Joystick device, legacy soundcard
emulation device (SoundBlaster) and MIDI serial device. Support for at least
ATAPI CD-ROM and Joystick is being worked on. This version of the driver will
use 1 IRQ and 2 DRQs.
HARDWARE
Cards supported by the
guspnp driver include:
- Gravis Ultrasound PNP, and compatibles
SEE ALSO
audio(4),
gus(4),
isapnp(4)
REFERENCES
Interwave(tm) IC Am78C201/202 Programmer's Guide Rev. 2. 1996. Advanced Micro
Devices.
HISTORY
The
guspnp driver appeared in
NetBSD
1.3.
AUTHORS
Kari Mettinen
<
Kari.Mettinen@helsinki.fi>,
University of Helsinki.
BUGS
Sometimes you can cause a hiss on either left or right channel, or both. You can
usually make it disappear by playing random data, however this might not be a
very nice thing to your audio equipment, but it is the only way I have found
out to be effective.
Only the Codec is used in this version of the driver, therefore only 2 channels
are supported (left and right). Also sound quality is probably worse at lower
kHz compared to playing through the synthesizer which does interpolation.
If the implementation has a 'bad' oscillator, using frequencies 44.8kHz and
38.4kHz will result in incorrect playback frequency. The author has a GUS PnP
Pro which displays this behavior.
Other members of the Interwave family have not been tested and don't have the
glue needed to make them work. Should someone need to implement it, not many
changes in the existing code are needed. Output voltage control in register
CFIG2 [7] should be set differently for some other members of the family.
Other architectures than i386 haven't been tested. The bus_space abstraction has
been used from the beginning, so it should work.