Initial push

1 files changed, 54 insertions, 0 deletions

diff --git a/stacks/tncs/docs/HYBBX-TNC2C.md b/stacks/tncs/docs/HYBBX-TNC2C.md
new file mode 100644
index 0000000..8d2207f
--- /dev/null
+++ b/stacks/tncs/docs/HYBBX-TNC2C.md
@@ -0,0 +1,54 @@
+# HyBBX + TNC2C
+
+MAX25 prepares the TNC (recovery + KISS entry); HyBBX attaches with **`kiss_entry = none`**.
+
+## Flow
+
+```
+max25d auto_start / max25-ctl start --hardware tncs --device tnc2c
+        ↓  (software recovery + kiss on)
+HyBBX Secondary starts packet_radio plugin (attach-only)
+        ↓
+KISS on serial → AX.25 sessions
+```
+
+Software recovery without power cycle: [TNC-RECOVERY.md](TNC-RECOVERY.md).
+
+## Preparation (MAX25)
+
+```bash
+./scripts/max25-ctl start --hardware tncs --device tnc2c
+# Production: max25d with [stack] auto_start = yes
+```
+
+One process per serial port — stop other userspace serial owners before HyBBX starts.
+
+## HyBBX INI
+
+Merge `share/hybbx/tnc2c-host.ini.example` or `stacks/tncs/hybbx-tnc2c.ini` into Secondary `hybbx.ini`:
+
+```ini
+[transport.packet_radio1]
+tnc = tnc2c
+device = /dev/ttyUSB0
+baud = 19200
+serial_line = 8n1
+rts_dtr = yes
+kiss_entry = none
+persist = 255
+
+[max25]
+check = yes
+```
+
+Set `device`, callsign, and frequency for your station.
+
+For HyBBX **without** max25d (standalone), use `kiss_entry = kiss_on` or `auto` instead — HyBBX runs its own recovery before KISS entry.
+
+## Checks
+
+- MAX25 prep returned host/KISS ready (boot-wait OK or max25d `ready`)
+- `fuser` on device is empty before HyBBX start (max25d holds port in production)
+- Log shows KISS active on the expected port
+
+Full contract: [docs/HYBBX.md](../../docs/HYBBX.md)