sethdlc - get/set Linux HDLC packet radio modem driver port information
sethdlc [ -bdhs ] [-i device]
sethdlc [-i device] -c cal
sethdlc -p [-i device]
[ mode mode
]
[ io iobase
]
[ irq irq
]
[ dma dma
]
[ dma2 dma2
]
[ serio seriobase
]
[ pario pariobase
]
[ midiio midiiobase
]
[ options options
]
sethdlc -a [-i device]
[ txd txdelay
]
[ txtail txtail
]
[ slot slottime
]
[ ppersist ppersistence
]
[ full ] [ half ]
sethdlc is a program designed to set and/or report the configuration
information associated with a soundcard radio modem port. This information
includes the modem type, what I/O port, IRQ and DMA channel a particular modem
port is using, and where to output a transmitter keying (PTT) signal.
With the
-p option,
sethdlc sets and/or reports the port
configuration.
With the
-a option,
sethdlc sets and/or reports the AX.25 channel
access parameters. These parameters can also be set with the
kissparms
utility.
With the
-c option,
sethdlc instructs the driver to send a
calibration pattern for
cal seconds.
Without the
-p, -a and
-c option,
sethdlc will stay
in the foreground and display received packets. The AX.25 header and
eventually a FlexNet compressed header are decoded. CTRL-C terminates
sethdlc. Specifying additional options,
sethdlc may display
additional information.
sethdlc accepts the following options:
- -b
- Trace the bits at the output of the demodulator, after RX
clock recovery. This option is only available if sethdlc and the
soundcard modem kernel driver is compiled with debugging support on. This
is useful for driver debugging.
- -d
- Trace DCD, PTT and other status information on stdout.
sethdlc displays two times per second a line containing this
information.
- -h
- Display an overview of the available command line
parameters and exit.
- -i
- The device argument specifies the HDLC modem device
which should be configured or interrogated. It will usually have the
following form: bc[0-3] for the baycom driver and sm[0-3]
for the soundcard modem driver.
- -s
- Trace the bits at the demodulator output, before the
RX clock recovery, to stdout. This option is only available the modem
driver is compiled with debugging support on. It may not be available on
some modem, such as the par96.
The following parameters can be assigned to a soundcard radio modem port.
All numerical parameter values are assumed to be in decimal unless preceded by
"0x".
The
mode parameter sets the type of hardware and the operating mode of
the driver.
ser12 and
par96 are valid modes for the
baycom driver. A star "
*" may be added to enable
software DCD. The
mode string format of the
soundmodem driver is
as follows:
hw:mode.
hw may be either
sbc,
wss or
wssfdx. The first one specifies SoundBlaster compatible soundcards, the
second one WindowsSoundSystem compatible hardware, and the third one WSS
fullduplex operation (which currently works with Crystal Semiconductor
Chipsets CS423[126]). The
mode portion may be
afsk1200 or
fsk9600. Optionally, the receive and transmit modes may be different (
hw:txmode.rxmode).
The
ioport parameter sets the I/O port address. Typical values for the
ser12 modem are 0x3f8, 0x2f8, 0x3e8 or 0x2e8, for the
par96
modem 0x378, 0x278 or 0x3bc, for the
sbc modems 0x220 and for the
wss modems 0x530, 0x608, 0xe80 or 0xf40.
The
irq parameter sets the hardware IRQ number. Typical values for the
ser12 modem are 4 and 3, for the
par96 modem 7 or 5, for the
sbc modems are 7 or 5 and for the
wss modems, any free IRQ from
the set 2, 7, 9, 10, 11 will do. The driver automatically configures the WSS
soundcard to the correct IRQ.
The
dma parameter sets the hardware DMA number. Typical values for the
sbc modems are 1 or 0 and for the
wss modems, any free DMA from
0 to 3 (except 2) will do. The driver automatically configures the WSS
soundcard to the correct DMA. The Baycom modems do not need DMA.
The
dma2 parameter sets the second hardware DMA number. This is only
needed for full duplex operation with the
soundmodem driver.
The
seriobase parameter optionally sets the address of a serial port,
where the driver will output a PTT signal at the TxD and RTS pins, and a DCD
signal at the DTR pin. As Baycom modems do have their own PTT pin, this
parameter is not used by the Baycom modem driver.
The
pariobase parameter optionally sets the address of a LPT port where
the driver will output a PTT signal on the DATA0 line and a DCD signal on the
DATA1 line. As Baycom modems do have their own PTT pin, this parameter is not
used by the Baycom modem driver.
The
midiiobase parameter optionally sets the address of a MPU401
compatible MIDI port, where the driver will output a PTT signal. Since the
MIDI port is effectively an UART and therefore cannot output a DC signal, the
output must be fed through a retriggerable monoflop with a period of about
15ms. See
http://www.ife.ee.ethz.ch/~sailer/pcf/ptt_circ/ptt.html for a
sample schematic diagram. As Baycom modems do have their own PTT pin, this
parameter is not used by the Baycom modem driver.
The
txdelay sets the transmitter keyup delay time. Unlike
kissparms, the unit is
tens of ms. This is the time the
transmitter needs to switch its PA on and for its frequency synthesizer to
settle. Typical values for a handheld transceiver are 200ms (i.e. 20), and for
a good crystal driven transceiver 20ms (i.e. 2).
The
txtail sets the time PTT is held after the last packet. Unlike
kissparms, the unit is
tens of ms. Do not set this value to 0.
Most modems need some extra time to actually clock the last bits out to the
transmitter.
The
slottime parameter specifies how often the channel access algorithm
is executed. Unlike
kissparms, the unit is
tens of ms. Unless
you have very specific requirements, set this to 100ms (i.e. 10).
The
ppersist sets how "eagerly" the station starts to transmit
as soon as the channel gets free. The optimum value is 256 divided by the
number of stations on the channel. (This should really be done automatically
by the L2)
full sets the modem to full duplex mode. Note that some modems do not
actually support full duplex mode, in this case this parameter makes the modem
start its transmission as soon as it gets packets from the upper layer,
without waiting for the channel to become free. This is needed by some
implementations of alternative channel access algorithms, e.g.
DAMA.
half sets the modem to half duplex mode.
It is important to note that sethdlc merely tells the Linux kernel where it
should expect to find the I/O port and IRQ lines of a particular serial port.
It does
not configure the hardware to use a particular I/O port. In
order to do that, you will need to physically program the serial board,
usually by setting some jumpers or by switching some DIP switches.
This section will provide some pointers in helping you decide how you would like
to configure your baycom ports.
The "standard MS-DOS" port associations are given below:
COM1, port 0x3f8, irq 4
COM2, port 0x2f8, irq 3
COM3, port 0x3e8, irq 4
COM4, port 0x2e8, irq 3
LPT1, port 0x378, irq 7
LPT1 (on hercules graphics adapter), port 0x3bc, irq 7
LPT1, port 0x278, irq 5
Some cards need to be initialized before they act as a WSS or SoundBlaster
compatible card. This driver does
not do this. You can use the standard
linux sound driver, if compiled as a module. Just load the sound driver
(insmod sound) and remove it again (rmmod sound). The card should then be
configured for either soundblaster or WSS compatibility. If this does not work
for some reason, you'll have to write your own soundcard configuration
utility. This is not as complicated as it sounds; it can be done from user
space (but requiring root privileges) using
ioperm and/or
iopl.
It is important that the audio levels of your radio match those of the
soundcard. To help achieve this, there are two utilities:
smdiag and
smmixer. See their respective manpage.
The sound driver and the soundcard modem driver are mutually exclusive, i.e.
they cannot both access the same soundcard at the same time. Even worse, the
sound driver reserves the soundcard as soon as it gets loaded. The souncard
modem driver however reserves the card only when the interface is started,
i.e. during ifconfig sm[0-3] up.
9600 baud may not currently work on SoundBlaster cards with DSP revision 4.x,
i.e. SB16 and SB32 AWE. This is because they seem to not be fully backwards
compatible.
CAUTION: Using an invalid port can lock up your machine.
smdiag (8), smmixer (8), kissparms (8),
linux/drivers/net/hdlcdrv.c,
linux/drivers/net/baycom.c,
linux/drivers/net/soundmodem.c
sethdlc was written by Thomas Sailer, HB9JNX/AE4WA (
[email protected]).
Inspired by setserial.