658 lines
20 KiB
Plaintext
658 lines
20 KiB
Plaintext
This is a subset of the documentation. To use this driver you MUST have the
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full package from:
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Internet:
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=========
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1. ftp://ftp.ccac.rwth-aachen.de/pub/jr/z8530drv-utils_3.0-3.tar.gz
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2. ftp://ftp.pspt.fi/pub/ham/linux/ax25/z8530drv-utils_3.0-3.tar.gz
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Please note that the information in this document may be hopelessly outdated.
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A new version of the documentation, along with links to other important
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Linux Kernel AX.25 documentation and programs, is available on
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http://yaina.de/jreuter
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-----------------------------------------------------------------------------
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SCC.C - Linux driver for Z8530 based HDLC cards for AX.25
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********************************************************************
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(c) 1993,2000 by Joerg Reuter DL1BKE <jreuter@yaina.de>
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portions (c) 1993 Guido ten Dolle PE1NNZ
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for the complete copyright notice see >> Copying.Z8530DRV <<
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********************************************************************
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1. Initialization of the driver
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===============================
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To use the driver, 3 steps must be performed:
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1. if compiled as module: loading the module
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2. Setup of hardware, MODEM and KISS parameters with sccinit
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3. Attach each channel to the Linux kernel AX.25 with "ifconfig"
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Unlike the versions below 2.4 this driver is a real network device
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driver. If you want to run xNOS instead of our fine kernel AX.25
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use a 2.x version (available from above sites) or read the
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AX.25-HOWTO on how to emulate a KISS TNC on network device drivers.
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1.1 Loading the module
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======================
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(If you're going to compile the driver as a part of the kernel image,
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skip this chapter and continue with 1.2)
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Before you can use a module, you'll have to load it with
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insmod scc.o
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please read 'man insmod' that comes with module-init-tools.
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You should include the insmod in one of the /etc/rc.d/rc.* files,
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and don't forget to insert a call of sccinit after that. It
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will read your /etc/z8530drv.conf.
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1.2. /etc/z8530drv.conf
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=======================
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To setup all parameters you must run /sbin/sccinit from one
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of your rc.*-files. This has to be done BEFORE you can
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"ifconfig" an interface. Sccinit reads the file /etc/z8530drv.conf
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and sets the hardware, MODEM and KISS parameters. A sample file is
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delivered with this package. Change it to your needs.
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The file itself consists of two main sections.
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1.2.1 configuration of hardware parameters
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==========================================
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The hardware setup section defines the following parameters for each
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Z8530:
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chip 1
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data_a 0x300 # data port A
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ctrl_a 0x304 # control port A
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data_b 0x301 # data port B
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ctrl_b 0x305 # control port B
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irq 5 # IRQ No. 5
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pclock 4915200 # clock
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board BAYCOM # hardware type
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escc no # enhanced SCC chip? (8580/85180/85280)
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vector 0 # latch for interrupt vector
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special no # address of special function register
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option 0 # option to set via sfr
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chip - this is just a delimiter to make sccinit a bit simpler to
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program. A parameter has no effect.
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data_a - the address of the data port A of this Z8530 (needed)
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ctrl_a - the address of the control port A (needed)
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data_b - the address of the data port B (needed)
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ctrl_b - the address of the control port B (needed)
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irq - the used IRQ for this chip. Different chips can use different
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IRQs or the same. If they share an interrupt, it needs to be
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specified within one chip-definition only.
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pclock - the clock at the PCLK pin of the Z8530 (option, 4915200 is
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default), measured in Hertz
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board - the "type" of the board:
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SCC type value
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---------------------------------
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PA0HZP SCC card PA0HZP
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EAGLE card EAGLE
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PC100 card PC100
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PRIMUS-PC (DG9BL) card PRIMUS
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BayCom (U)SCC card BAYCOM
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escc - if you want support for ESCC chips (8580, 85180, 85280), set
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this to "yes" (option, defaults to "no")
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vector - address of the vector latch (aka "intack port") for PA0HZP
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cards. There can be only one vector latch for all chips!
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(option, defaults to 0)
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special - address of the special function register on several cards.
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(option, defaults to 0)
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option - The value you write into that register (option, default is 0)
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You can specify up to four chips (8 channels). If this is not enough,
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just change
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#define MAXSCC 4
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to a higher value.
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Example for the BAYCOM USCC:
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----------------------------
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chip 1
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data_a 0x300 # data port A
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ctrl_a 0x304 # control port A
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data_b 0x301 # data port B
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ctrl_b 0x305 # control port B
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irq 5 # IRQ No. 5 (#)
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board BAYCOM # hardware type (*)
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#
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# SCC chip 2
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#
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chip 2
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data_a 0x302
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ctrl_a 0x306
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data_b 0x303
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ctrl_b 0x307
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board BAYCOM
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An example for a PA0HZP card:
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-----------------------------
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chip 1
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data_a 0x153
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data_b 0x151
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ctrl_a 0x152
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ctrl_b 0x150
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irq 9
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pclock 4915200
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board PA0HZP
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vector 0x168
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escc no
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#
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#
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#
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chip 2
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data_a 0x157
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data_b 0x155
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ctrl_a 0x156
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ctrl_b 0x154
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irq 9
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pclock 4915200
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board PA0HZP
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vector 0x168
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escc no
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A DRSI would should probably work with this:
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--------------------------------------------
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(actually: two DRSI cards...)
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chip 1
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data_a 0x303
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data_b 0x301
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ctrl_a 0x302
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ctrl_b 0x300
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irq 7
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pclock 4915200
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board DRSI
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escc no
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#
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#
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#
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chip 2
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data_a 0x313
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data_b 0x311
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ctrl_a 0x312
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ctrl_b 0x310
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irq 7
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pclock 4915200
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board DRSI
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escc no
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Note that you cannot use the on-board baudrate generator off DRSI
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cards. Use "mode dpll" for clock source (see below).
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This is based on information provided by Mike Bilow (and verified
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by Paul Helay)
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The utility "gencfg"
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--------------------
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If you only know the parameters for the PE1CHL driver for DOS,
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run gencfg. It will generate the correct port addresses (I hope).
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Its parameters are exactly the same as the ones you use with
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the "attach scc" command in net, except that the string "init" must
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not appear. Example:
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gencfg 2 0x150 4 2 0 1 0x168 9 4915200
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will print a skeleton z8530drv.conf for the OptoSCC to stdout.
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gencfg 2 0x300 2 4 5 -4 0 7 4915200 0x10
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does the same for the BAYCOM USCC card. In my opinion it is much easier
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to edit scc_config.h...
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1.2.2 channel configuration
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===========================
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The channel definition is divided into three sub sections for each
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channel:
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An example for scc0:
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# DEVICE
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device scc0 # the device for the following params
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# MODEM / BUFFERS
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speed 1200 # the default baudrate
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clock dpll # clock source:
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# dpll = normal half duplex operation
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# external = MODEM provides own Rx/Tx clock
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# divider = use full duplex divider if
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# installed (1)
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mode nrzi # HDLC encoding mode
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# nrzi = 1k2 MODEM, G3RUH 9k6 MODEM
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# nrz = DF9IC 9k6 MODEM
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#
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bufsize 384 # size of buffers. Note that this must include
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# the AX.25 header, not only the data field!
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# (optional, defaults to 384)
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# KISS (Layer 1)
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txdelay 36 # (see chapter 1.4)
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persist 64
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slot 8
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tail 8
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fulldup 0
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wait 12
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min 3
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maxkey 7
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idle 3
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maxdef 120
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group 0
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txoff off
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softdcd on
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slip off
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The order WITHIN these sections is unimportant. The order OF these
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sections IS important. The MODEM parameters are set with the first
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recognized KISS parameter...
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Please note that you can initialize the board only once after boot
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(or insmod). You can change all parameters but "mode" and "clock"
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later with the Sccparam program or through KISS. Just to avoid
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security holes...
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(1) this divider is usually mounted on the SCC-PBC (PA0HZP) or not
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present at all (BayCom). It feeds back the output of the DPLL
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(digital pll) as transmit clock. Using this mode without a divider
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installed will normally result in keying the transceiver until
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maxkey expires --- of course without sending anything (useful).
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2. Attachment of a channel by your AX.25 software
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=================================================
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2.1 Kernel AX.25
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================
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To set up an AX.25 device you can simply type:
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ifconfig scc0 44.128.1.1 hw ax25 dl0tha-7
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This will create a network interface with the IP number 44.128.20.107
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and the callsign "dl0tha". If you do not have any IP number (yet) you
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can use any of the 44.128.0.0 network. Note that you do not need
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axattach. The purpose of axattach (like slattach) is to create a KISS
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network device linked to a TTY. Please read the documentation of the
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ax25-utils and the AX.25-HOWTO to learn how to set the parameters of
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the kernel AX.25.
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2.2 NOS, NET and TFKISS
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=======================
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Since the TTY driver (aka KISS TNC emulation) is gone you need
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to emulate the old behaviour. The cost of using these programs is
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that you probably need to compile the kernel AX.25, regardless of whether
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you actually use it or not. First setup your /etc/ax25/axports,
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for example:
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9k6 dl0tha-9 9600 255 4 9600 baud port (scc3)
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axlink dl0tha-15 38400 255 4 Link to NOS
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Now "ifconfig" the scc device:
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ifconfig scc3 44.128.1.1 hw ax25 dl0tha-9
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You can now axattach a pseudo-TTY:
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axattach /dev/ptys0 axlink
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and start your NOS and attach /dev/ptys0 there. The problem is that
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NOS is reachable only via digipeating through the kernel AX.25
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(disastrous on a DAMA controlled channel). To solve this problem,
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configure "rxecho" to echo the incoming frames from "9k6" to "axlink"
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and outgoing frames from "axlink" to "9k6" and start:
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rxecho
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Or simply use "kissbridge" coming with z8530drv-utils:
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ifconfig scc3 hw ax25 dl0tha-9
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kissbridge scc3 /dev/ptys0
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3. Adjustment and Display of parameters
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=======================================
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3.1 Displaying SCC Parameters:
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==============================
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Once a SCC channel has been attached, the parameter settings and
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some statistic information can be shown using the param program:
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dl1bke-u:~$ sccstat scc0
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Parameters:
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speed : 1200 baud
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txdelay : 36
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persist : 255
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slottime : 0
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txtail : 8
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fulldup : 1
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waittime : 12
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mintime : 3 sec
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maxkeyup : 7 sec
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idletime : 3 sec
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maxdefer : 120 sec
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group : 0x00
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txoff : off
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softdcd : on
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SLIP : off
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Status:
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HDLC Z8530 Interrupts Buffers
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-----------------------------------------------------------------------
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Sent : 273 RxOver : 0 RxInts : 125074 Size : 384
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Received : 1095 TxUnder: 0 TxInts : 4684 NoSpace : 0
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RxErrors : 1591 ExInts : 11776
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TxErrors : 0 SpInts : 1503
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Tx State : idle
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The status info shown is:
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Sent - number of frames transmitted
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Received - number of frames received
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RxErrors - number of receive errors (CRC, ABORT)
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TxErrors - number of discarded Tx frames (due to various reasons)
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Tx State - status of the Tx interrupt handler: idle/busy/active/tail (2)
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RxOver - number of receiver overruns
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TxUnder - number of transmitter underruns
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RxInts - number of receiver interrupts
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TxInts - number of transmitter interrupts
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EpInts - number of receiver special condition interrupts
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SpInts - number of external/status interrupts
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Size - maximum size of an AX.25 frame (*with* AX.25 headers!)
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NoSpace - number of times a buffer could not get allocated
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An overrun is abnormal. If lots of these occur, the product of
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baudrate and number of interfaces is too high for the processing
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power of your computer. NoSpace errors are unlikely to be caused by the
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driver or the kernel AX.25.
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3.2 Setting Parameters
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======================
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The setting of parameters of the emulated KISS TNC is done in the
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same way in the SCC driver. You can change parameters by using
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the kissparms program from the ax25-utils package or use the program
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"sccparam":
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sccparam <device> <paramname> <decimal-|hexadecimal value>
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You can change the following parameters:
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param : value
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------------------------
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speed : 1200
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txdelay : 36
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persist : 255
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slottime : 0
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txtail : 8
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fulldup : 1
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waittime : 12
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mintime : 3
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maxkeyup : 7
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idletime : 3
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maxdefer : 120
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group : 0x00
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txoff : off
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softdcd : on
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SLIP : off
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The parameters have the following meaning:
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speed:
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The baudrate on this channel in bits/sec
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Example: sccparam /dev/scc3 speed 9600
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txdelay:
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The delay (in units of 10 ms) after keying of the
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transmitter, until the first byte is sent. This is usually
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called "TXDELAY" in a TNC. When 0 is specified, the driver
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will just wait until the CTS signal is asserted. This
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assumes the presence of a timer or other circuitry in the
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MODEM and/or transmitter, that asserts CTS when the
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transmitter is ready for data.
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A normal value of this parameter is 30-36.
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Example: sccparam /dev/scc0 txd 20
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persist:
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This is the probability that the transmitter will be keyed
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when the channel is found to be free. It is a value from 0
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to 255, and the probability is (value+1)/256. The value
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should be somewhere near 50-60, and should be lowered when
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the channel is used more heavily.
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Example: sccparam /dev/scc2 persist 20
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slottime:
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This is the time between samples of the channel. It is
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expressed in units of 10 ms. About 200-300 ms (value 20-30)
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seems to be a good value.
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Example: sccparam /dev/scc0 slot 20
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tail:
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The time the transmitter will remain keyed after the last
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byte of a packet has been transferred to the SCC. This is
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necessary because the CRC and a flag still have to leave the
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SCC before the transmitter is keyed down. The value depends
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on the baudrate selected. A few character times should be
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sufficient, e.g. 40ms at 1200 baud. (value 4)
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The value of this parameter is in 10 ms units.
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Example: sccparam /dev/scc2 4
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full:
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The full-duplex mode switch. This can be one of the following
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values:
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0: The interface will operate in CSMA mode (the normal
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half-duplex packet radio operation)
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1: Fullduplex mode, i.e. the transmitter will be keyed at
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any time, without checking the received carrier. It
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will be unkeyed when there are no packets to be sent.
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2: Like 1, but the transmitter will remain keyed, also
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when there are no packets to be sent. Flags will be
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sent in that case, until a timeout (parameter 10)
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occurs.
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Example: sccparam /dev/scc0 fulldup off
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wait:
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The initial waittime before any transmit attempt, after the
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frame has been queue for transmit. This is the length of
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the first slot in CSMA mode. In full duplex modes it is
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set to 0 for maximum performance.
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The value of this parameter is in 10 ms units.
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Example: sccparam /dev/scc1 wait 4
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maxkey:
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The maximal time the transmitter will be keyed to send
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packets, in seconds. This can be useful on busy CSMA
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channels, to avoid "getting a bad reputation" when you are
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generating a lot of traffic. After the specified time has
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elapsed, no new frame will be started. Instead, the trans-
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mitter will be switched off for a specified time (parameter
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min), and then the selected algorithm for keyup will be
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started again.
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The value 0 as well as "off" will disable this feature,
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and allow infinite transmission time.
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Example: sccparam /dev/scc0 maxk 20
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min:
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This is the time the transmitter will be switched off when
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the maximum transmission time is exceeded.
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Example: sccparam /dev/scc3 min 10
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idle
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This parameter specifies the maximum idle time in full duplex
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2 mode, in seconds. When no frames have been sent for this
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time, the transmitter will be keyed down. A value of 0 is
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has same result as the fullduplex mode 1. This parameter
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can be disabled.
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Example: sccparam /dev/scc2 idle off # transmit forever
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maxdefer
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This is the maximum time (in seconds) to wait for a free channel
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to send. When this timer expires the transmitter will be keyed
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IMMEDIATELY. If you love to get trouble with other users you
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should set this to a very low value ;-)
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Example: sccparam /dev/scc0 maxdefer 240 # 2 minutes
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txoff:
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When this parameter has the value 0, the transmission of packets
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is enable. Otherwise it is disabled.
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Example: sccparam /dev/scc2 txoff on
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group:
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|
It is possible to build special radio equipment to use more than
|
|
one frequency on the same band, e.g. using several receivers and
|
|
only one transmitter that can be switched between frequencies.
|
|
Also, you can connect several radios that are active on the same
|
|
band. In these cases, it is not possible, or not a good idea, to
|
|
transmit on more than one frequency. The SCC driver provides a
|
|
method to lock transmitters on different interfaces, using the
|
|
"param <interface> group <x>" command. This will only work when
|
|
you are using CSMA mode (parameter full = 0).
|
|
The number <x> must be 0 if you want no group restrictions, and
|
|
can be computed as follows to create restricted groups:
|
|
<x> is the sum of some OCTAL numbers:
|
|
|
|
200 This transmitter will only be keyed when all other
|
|
transmitters in the group are off.
|
|
100 This transmitter will only be keyed when the carrier
|
|
detect of all other interfaces in the group is off.
|
|
0xx A byte that can be used to define different groups.
|
|
Interfaces are in the same group, when the logical AND
|
|
between their xx values is nonzero.
|
|
|
|
Examples:
|
|
When 2 interfaces use group 201, their transmitters will never be
|
|
keyed at the same time.
|
|
When 2 interfaces use group 101, the transmitters will only key
|
|
when both channels are clear at the same time. When group 301,
|
|
the transmitters will not be keyed at the same time.
|
|
|
|
Don't forget to convert the octal numbers into decimal before
|
|
you set the parameter.
|
|
|
|
Example: (to be written)
|
|
|
|
softdcd:
|
|
use a software dcd instead of the real one... Useful for a very
|
|
slow squelch.
|
|
|
|
Example: sccparam /dev/scc0 soft on
|
|
|
|
|
|
4. Problems
|
|
===========
|
|
|
|
If you have tx-problems with your BayCom USCC card please check
|
|
the manufacturer of the 8530. SGS chips have a slightly
|
|
different timing. Try Zilog... A solution is to write to register 8
|
|
instead to the data port, but this won't work with the ESCC chips.
|
|
*SIGH!*
|
|
|
|
A very common problem is that the PTT locks until the maxkeyup timer
|
|
expires, although interrupts and clock source are correct. In most
|
|
cases compiling the driver with CONFIG_SCC_DELAY (set with
|
|
make config) solves the problems. For more hints read the (pseudo) FAQ
|
|
and the documentation coming with z8530drv-utils.
|
|
|
|
I got reports that the driver has problems on some 386-based systems.
|
|
(i.e. Amstrad) Those systems have a bogus AT bus timing which will
|
|
lead to delayed answers on interrupts. You can recognize these
|
|
problems by looking at the output of Sccstat for the suspected
|
|
port. If it shows under- and overruns you own such a system.
|
|
|
|
Delayed processing of received data: This depends on
|
|
|
|
- the kernel version
|
|
|
|
- kernel profiling compiled or not
|
|
|
|
- a high interrupt load
|
|
|
|
- a high load of the machine --- running X, Xmorph, XV and Povray,
|
|
while compiling the kernel... hmm ... even with 32 MB RAM ... ;-)
|
|
Or running a named for the whole .ampr.org domain on an 8 MB
|
|
box...
|
|
|
|
- using information from rxecho or kissbridge.
|
|
|
|
Kernel panics: please read /linux/README and find out if it
|
|
really occurred within the scc driver.
|
|
|
|
If you cannot solve a problem, send me
|
|
|
|
- a description of the problem,
|
|
- information on your hardware (computer system, scc board, modem)
|
|
- your kernel version
|
|
- the output of cat /proc/net/z8530
|
|
|
|
4. Thor RLC100
|
|
==============
|
|
|
|
Mysteriously this board seems not to work with the driver. Anyone
|
|
got it up-and-running?
|
|
|
|
|
|
Many thanks to Linus Torvalds and Alan Cox for including the driver
|
|
in the Linux standard distribution and their support.
|
|
|
|
Joerg Reuter ampr-net: dl1bke@db0pra.ampr.org
|
|
AX-25 : DL1BKE @ DB0ABH.#BAY.DEU.EU
|
|
Internet: jreuter@yaina.de
|
|
WWW : http://yaina.de/jreuter
|