WA8DED hostmode

AXLoRaTNC implements the WA8DED binary host mode protocol for legacy host software. For LinFBB/F6FBB, the recommended setup is KISS through Linux AX.25; see the FBB KISS guide.

Enable hostmode

From the console:

mode ded

The mode is stored in NVS and persists across reboots. To return to the interactive console from any mode, send the plain text string console followed by Enter (CR).

Frame format

host → tnc:  [channel] [cmd] [count] [data…]
tnc  → host: [channel] [code] [data…]

• channel: 1–8 for connected channels, 0 for UI/unproto
• cmd: 0 = info/data frame; 1 = command frame
• count: number of data bytes minus 1 (data frames); for command frames this is the command length
• code: 0 = ack/no event; 1 = info text; 2 = error; 3 = link status; 4 = monitor header; 5 = monitor frame; 6 = connected data; 7 = UI data

Channels

Range	Purpose
0	UI / unproto (broadcast)
1–8	Connected AX.25 channels

Commands (hostmode)

Connection control

Command	Function
G	Poll for any pending event
G0	Poll for link-status events only (code 3)
G1	Poll for data and link-status events (codes 3, 6, 7)
C <CALL>	Connect to CALL on the selected channel
D	Disconnect the selected channel
I	Query own callsign
I <CALL>	Set own callsign
L	Query link status
JHOST0	Leave hostmode, return to terminal mode
JHOST1	Enter binary hostmode (TNC responds with ack)
V	Query firmware version string
S	Query selected channel
S <n>	Select channel n (0–8)

Parameters

All parameters can be queried (send without argument → TNC replies with current value as info text) or set (send with numeric argument → TNC replies with ack 0). All settings persist in NVS.

Cmd	Parameter	Default	Range
A	Auto-LF (append LF after CR)	1	0–1
B	DAMA timeout (× 100 ms)	120	0–255
E	Echo (terminal mode)	1	0–1
F	FRACK — T1 retry timer (× 100 ms)	250	0–255
K	Timestamp in monitor output	0	0–1
N	Retry limit (N2)	10	0–127
O	Max outstanding frames (window, MAXFRAME)	2	1–7
P	CSMA persistence (0–255, p = (n+1)/256)	63	0–255
R	Digipeater on/off	0	0–1
T	TX delay (× 10 ms)	30	0–127
W	Slot time (× 10 ms)	10	0–127
X	TX enable	1	0–1
Y	Max incoming connections	4	0–8
Z	Flow control: bit 0 = RTS/CTS, bit 1 = XON/XOFF	3	0–3
M	Monitor mode string	IU	see below
U	Unattended mode + connect text	0	0–2

Monitor mode (M)

M queries the current monitor mode string. M <string> sets it. Use M N to disable monitoring.

Monitor mode letters select which frame types are reported:

Letter	Frames reported
I	I-frames (connected data)
U	Unnumbered frames (UI, SABM, UA, DISC, DM, FRMR)
S	Supervisory frames (RR, RNR, REJ, SREJ)
N	None (monitor disabled)

Example: M IU (default) reports UI traffic and connection control frames but not RR/RNR supervisory frames.

Buffer query (@B)

Query the number of free TX buffers available on the selected channel:

host → tnc:  [ch] [1] [2] @B\0
tnc  → host: [ch] [1] <free-buffers as text>

Reset to defaults (@Q / QRES)

Resets all DED parameters to factory defaults and saves them to NVS.

PACLEN (IPOLL)

Sets the maximum I-frame info field size in bytes (default 60). Large frames are automatically fragmented into PACLEN-sized chunks before being queued to the AX.25 layer.

host → tnc:  [ch] [1] [n] IPOLL <value>\0

Terminal mode (before JHOST1)

In terminal mode (after mode ded but before JHOST1) the TNC accepts plain text commands, one per line. All single-letter parameters above are accepted, plus:

Command	Function
MYCALL [CALL]	Query or set own callsign
UNPROTO [DEST]	Query or set unproto destination
BTEXT [text]	Query or set beacon text
CONNECT <CALL>	Connect on current channel
DISCONNECT	Disconnect current channel
JHOST1	Switch to binary hostmode
QRES	Reset all DED parameters to defaults

Event codes (TNC → host)

Code	Meaning	Data
0	Acknowledgement / no event	none
1	Informational text	null-terminated string
2	Error text	null-terminated string
3	Link status change	null-terminated string (see below)
4	Monitor frame header (terminal mode)	null-terminated string
5	Monitor frame header (hostmode)	null-terminated string
6	Connected data received	length-prefixed bytes
7	UI data received	length-prefixed bytes

Link status strings (code 3)

String	Meaning
CONNECTED to <CALL>	Incoming or outgoing connection established
DISCONNECTED fm <CALL>	Link cleanly disconnected
DISCONNECTING fm <CALL>	Disconnect in progress
LINK FAILURE with <CALL>	T1 retry limit exceeded (Recovery state)
LINK RESET to station <CALL>	SABM received while already connected

In hostmode the channel number is in the frame header byte — the status string contains only the text above. In terminal mode the string is prefixed with (n) so the operator knows which channel changed.

Monitor frame format (code 5)

FM <SRC> TO <DST> [VIA <R1>,<R2>] <TYPE> RSSI=<x> SNR=<y>[:<info>]

<TYPE> is one of: UI, I, RR, RNR, REJ, SREJ, SABM, UA, DISC, DM, FRMR.

Flow control

XON/XOFF (enabled by default, Z bit 1): 0x13 (XOFF) pauses TNC output; 0x11 (XON) resumes. In binary hostmode the control bytes are detected at frame boundaries so they cannot collide with channel bytes.

Hardware RTS/CTS (enabled when variant defines PIN_UART_RTS/PIN_UART_CTS): the UART hardware flow control lines are asserted automatically.

Compatible software

Software	Setup notes
F6FBB	Host type D; set port to the ESP32 serial port
TFPCX + TSTHOST	Load TFPCX first (tfpcx -pCOM1 -b9600), then launch TSTHOST
WinPack	Select TNC type WA8DED, set COM port and baud rate
BPQ32 / LinBPQ	Use port type DED; set PORTCOM to the ESP32 serial device
JNOS	Interface type asy with tnc set to ded
Graphic Packet	Direct WA8DED port
PaxTerm	Direct WA8DED port

AX.25 link layer settings

The following AX.25 parameters are shared between KISS and WA8DED modes:

Parameter	Default	DED command
T1 retry timer	25 s (F × 100 ms)	F
T2 deferred-ack	1.5 s	@T2
T3 keepalive	180 s	@T3
N2 retry limit	10	N
Window size (MAXFRAME)	2	O
PACLEN (info field)	60 bytes	IPOLL