wa8ded.doc
                             AX.25 Version 2
                              Multi-channel
                              TNC  FIRMWARE
                              (version 0.5)
                Copyright 1985, Ronald E. Raikes (WA8DED)
    This firmware supports the full AX.25 link layer protocol, version 2.0
as described in the ARRL specification dated October 1984, as well as the
pre-existing version 1.x.  This implementation supports multiple
simultaneous link connections with either version protocol.  This release
has been assembled for a maximum of four simultaneous connections.  Which
protocol version is used to initiate a connection is controlled by a tnc
command, but the version will be automatically changed, if necessary, to
conform to the version of the tnc responding. (NOTE: The existing firmware
supplied by TAPR for the TNC-1 will NOT digipeat version 2 protocol.)
    The firmware is contained in one 2764 EPROM, and is intended to be
installed in a TAPR TNC-1 (or equivalent, such as the AEA PKT-1 or Heath
HD-4040) in socket U12.  This assumes that a 6264 RAM is already installed
in socket U7, with an additional 6264 RAM optionally installed in socket U8
(recommended if multi-channel operation is intended).  The tnc parallel port
is not currently used.
    When installing the EPROM in U12 the first time, it will be necessary
to start the tnc with the PARAMETER SOURCE switch set to the PROM position.
This will cause default parameters to be written into NOVRAM memory but not
PERMed.  The RS-232 port will be initialized to 300 baud with no
handshaking.  The tnc source call sign will be all blanks, and should be set
with the 'I' command, as well as any other default parameters that might
need changing, before issuing a 'PERM' command.  At this point, the
PARAMETER SOURCE switch may be set to NOVRAM for subsequent operation.  If
the terminal baud rate has been changed, the new value will take effect
following a reset.
    All information sent to the tnc is in the form of lines, terminated by
a CARRIAGE RETURN character.  BACKSPACE and DELETE may be used to remove
single characters from the line.  The entire line may be backspaced out by
entering a CONTROL-U or CONTROL-X.  Lines beginning with an ESCAPE character
(echoed as '* ') are interpreted as commands.  If a command is issued with
no parameter, the current value of that commands parameter is displayed.
Lines without a leading ESCAPE character are sent as data.  Data sent to
channel 0 or a non-zero channel number that is not currently connected, will
be sent out unproto.  Data lines may be up to 256 characters long, including
the terminating CARRIAGE RETURN character.
    The firmware source is written in 6809 assembly language.  Emphasis was
placed on using a state table driven design, utilizing the state tables
provided in the ARRL specification.  The source was assembled using a 6809
cross assembler from 2500 AD Software running on a Z-80/8086 TurboDOS
development system (CP/M compatable).
                             COMMAND SUMMARY
                             ===============
COMMAND        PARAMETER               DESCRIPTION
-------        ---------               -----------
 A (1)            0             Auto linefeed disabled
                  1             Auto linefeed enabled
 B (6)           1-15           Terminal baud rate
* C        Cs1 [Cs2 ... Cs9]     Connect path (0=unproto path)
* D                              Disconnect
 E (1)            0             Echo command line disabled
                  1             Echo command line enabled
* F (4)           1-15           Frame acknowledge (seconds)
 H (1200)       50-4800         HDLC baud rate
 I                Cs            I am (MYCALL)
 K               1-4            Calibrate
 L              [0-4]           Display link status
 M (1)            0             Monitor always disabled
                  1             Monitor enabled if disconnected
                  2             Monitor always enabled
* N (10)         0-255           Number of tries (0=forever)
* O (4)           1-7            Number of outstanding I frames
 PERM                           Save parameters to NOVRAM
 QRES                           Re-start firmware
 R (1)            0             Repeater disabled
                  1             Repeater enabled
 S (1)           0-4            Channel number (0=unproto)
 T (4)           1-16           Transmitter delay (40ms)
 U (1)            0             Flow control disabled
                  1             Flow control enabled
* V (1)            1             Version 1 protocol initiated
                  2             Version 2 protocol initiated
 W (2)           0-15           Repeater wait (40ms)
 X (1)            0             Transmitter PTT disabled
                  1             Transmitter PTT enabled
 Y (1)           0-4            Maximum connections
  Default values are shown in parenthesis
*  These commands are applicable to each connection channel
    (Values set on channel 0 are used after a reset and
     disconnect to initialize each connection channel)
                           COMMAND DESCRIPTION
                           ===================
    The 'A' command is used to enable or disable the automatic insertion of
LINEFEED characters after CARRIAGE RETURN characters to the terminal.  This
parameter is stored in NOVRAM.
    The 'B' command is used to set the terminal baud rate, using one of the
following parameters:
    Parameter     Baud rate
    ---------     ---------
        1            50
        2            75
        3            110
        4            135
        5            150
        6            300
        7            600
        8            1200
        9            1800
       10            2400
       11            3600
       12            4800
       13            7200
       14            9600
       15            19200
After setting the baud rate with the 'B' command, the value must be PERMed,
and will then take effect following a reset.
    The 'C' command is used to initiate a link connection.  Note that NO
'v' or 'via' is used between the destination call sign and the digipeater
call signs.  A 'C' command may be issued on a channel already in use to
change the digipeater call signs, but not the destination call sign.  A 'C'
command issued when channel 0 is selected sets the unproto path.
    The 'D' command is used to initiate a link disconnection.  A 'D' command
issued during the establishment or dis-establishment of a link will cause an
immediate return to the disconnected state.
    The 'E' command is used to enable or disable the echoing of input
(commands and data) to the terminal.  This parameter is stored in NOVRAM.
    The 'F' command is used to set the frame acknowledgement interval.
This interval is used to compute the timeout interval before a packet is
retransmitted, using the formula:
       time (seconds) = frame ack * (2 * number of digipeaters + 1)
    A separate frame acknowlegement interval value is maintained for each
connection channel.  The value stored in channel 0 is used to initialize
each connection channel after a reset or disconnection, and is the value
that is stored in NOVRAM.
    The 'H' command is used to set the HDLC baud rate.  Non-standard values
are rounded down to the next possible baud rate.  In this case, use an 'H'
command with no paramter to display the value actually set.  This parameter
is stored in NOVRAM.  (A version of the firmware is available for use on
tnc's running at the faster clock speed.  HDLC rates up to 9600 baud are
supported and command parameters do not require doubling.)
    The 'I' command is used to set the tnc source call sign.  The initial
value is all blanks.  After the source call sign has been entered, the
'PERM' command should be used to save it for use during subsequent
operation.
    The 'K' command is used to calibrate the tnc modem.  The following
parameters set the calibration modes listed:
    Parameter     Calibration
    ---------     -----------
        1          Modem PLL
        2          Low  tone
        3          High tone
        4          Level/Null
This table may be be displayed on the terminal by issuing a 'K' command with
no parameter.  The first three calibration modes will display the measured
frequency on the terminal.  When each mode is selected, jumpers settings are
displayed as well as the appropriate ajustment point.  The value shown in
parenthesis is the normal setting for 1200 baud operation.
    The 'L' command is used to display the link status of one or all
channels.  Information displayed includes the connection path, number of
receive frames not yet displayed, number of send frames not yet transmitted,
number of transmitted frames not yet acknowledged, and the current retry
count.  A '+' character preceeding the channel number indicates the
currently selected channel.
    The 'M' command is used to set the monitor mode.  When channel 0 is
selected, monitoring will be enabled if either mode 1 or 2 is set.  This
parameter is stored in NOVRAM.  When monitoring is enabled, the control and
protocol identifier fields are both displayed in hexadecimal.  A brief
listing of the common control field values is included at the end of this
document.  Currently, the pid field is always an F0, signifying that no
layer 3 is implemented.
    The 'N' command is used to set the maximum number of times a frame will
be transmitted without receiving an appropriate acknowledgement, before a
link failure is assumed.  A separate maximum number of tries value is
maintained for each connection channel.  The value stored in channel 0 is
used to initialize each connection channel after a reset or disconnection,
and is the value that is stored in NOVRAM.
    The 'O' command is used to set the maximum number of unacknowledged I
frames that may be outstanding at any one time.  A separate maximum number
of unacknowledged I frames value is maintained for each connection channel.
The value stored in channel 0 is used to initialize each connection channel
after a reset or disconnection, and is the value that is stored in NOVRAM.
    The 'PERM' command is used to change the parameter values stored in
NOVRAM to those that are currently set.
    The 'QRES' command is used to restart the firmware as if a hardware
reset had been issued.
    The 'R' command is used to enable or disable the digipeating of frames.
This parameter is stored in NOVRAM.
    The 'S' command is used to select the current channel number.  This
parameter is stored in NOVRAM.
    The 'T' command is used to set the transmitter keyup delay interval.
The parameter is specified in 40ms increments.  This parameter is stored in
NOVRAM.
    The 'U' command is used to enable or disable flow control to the
terminal.  If flow control is enabled, output to the terminal will be
inhibited while entering commands or data.  If flow control is disabled,
output to the terminal will not be restricted.  Flow control should be
disabled during periods in which the tnc is operated without a terminal, to
avoid suspending output which will consume buffers.  This parameter is
stored in NOVRAM.
    The 'V' command is used to select whether version 1 or 2 protocol will
be used to initiate a link connection.  A separate protocol version number
value is maintained for each connection channel.  The value stored in
channel 0 is used to initialize each connection channel after a reset or
disconnection, and is the value that is stored in NOVRAM.
    The 'W' command is used to set the digipeater wait interval.  The
parameter is specified in 40ms increments.  This parameter is stored in
NOVRAM.
    The 'X' command is used to enable or disable the transmitter PTT
control line.  This parameter is stored in NOVRAM.
    The 'Y' command is used to set the maximum number of connections that
may established by incoming requests.  This command has no effect on the
operators ability to initiate outgoing connection requests.  This parameter
is stored in NOVRAM.
                            DEFAULT PARAMETERS
                            ==================
    In some instances, it may be desirable to have default parameters which
differ from the standard values.  To allow easy access, all default
parameters have been placed at the beginning of the EPROM.  The following
listing defines the layout of this area:
    TYPE     VALUE          DESCRIPTION
    ----     -----          -----------
    BYTE      1BH           COMMAND CHARACTER
    BYTE     '      ',60H   SOURCE CALL SIGN (SEE NOTE 1)
    WORD     000AH          HDLC BAUD RATE DIVISOR (SEE NOTE 2)
    BYTE      06H           TERMINAL BAUD RATE
    BYTE      01H           MAXIMUM CONNECTIONS
    BYTE      01H           MONITOR MODE
    BYTE      01H           REPEATER DISABLE/ENABLE
    BYTE      02H           REPEATER WAIT (40ms)
    BYTE      04H           TRANSMITTER DELAY (40ms)
    BYTE      01H           FLOW CONTROL DISABLE/ENABLE
    BYTE      01H           TRANSMITTER PTT DISABLE/ENABLE
    BYTE      01H           CHANNEL NUMBER
    BYTE      01H           AUTO LINEFEED DISABLE/ENABLE
    BYTE      01H           ECHO COMMAND LINE DISABLE/ENABLE
    BYTE      00H           VERSION 2 INITIATED DISABLE/ENABLE
    BYTE      04H           MAXIMUM UNACKNOWLEDGED FRAMES
    BYTE      0AH           MAXIMUM TRY COUNT
    BYTE      04H           FRAME ACKNOWLEDGE INTERVAL
    BYTE     'CQ    ',60H   UNPROTO CALL SIGN
DISABLE = 00H / ENABLE = 01H
NOTE 1: The secondary station id must be shifted left one bit and or'ed with
60H.
NOTE 2: The HDLC baud rate divisor is computed using the formula:
         divisor = (14400 / buad rate) - 2
The HDLC baud rate divisor is stored most significant byte first.
                           CONTROL FIELD VALUES
                           ====================
    VALUE     DESCRIPTION
    -----     -----------
     x1       RR   - Receive Ready
     x5       RNR  - Receive Not Ready
     x9       REJ  - Reject
     03       UI   - Unnumbered Information
     0F       DM   - Disconnected Mode
     2F       SABM - Connect Request
     43       DISC - Disconnect Request
     63       UA   - Unnumbered Acknowledge
     87       FRMR - Frame Reject
     Even     I    - Information (x0,x2,x4,x6,x8,xA,xC,xE)
NOTE:  In some instances, the above values may have 10H added to them, which
is the poll/final bit set.  For more information, see ARRL AX.25 Amateur
Packet-Radio Link-Layer Protocol specification, Version 2.0, dated October
1984.
At W6CUS: Date 850710 Time 1132 Last msg # 30, 9 active msgs

You are viewing proxied material from ftp.icm.edu.pl. The copyright of proxied material belongs to its original authors. Any comments or complaints in relation to proxied material should be directed to the original authors of the content concerned. Please see the disclaimer for more details.