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diff --git a/firmware/c1224/README.md b/firmware/c1224/README.md new file mode 100644 index 0000000..298dc64 --- /dev/null +++ b/firmware/c1224/README.md @@ -0,0 +1,116 @@ +# T-Modem-c1224 — Pico USB KISS half-TNC firmware + +**AS-IS** · GPLv3 (repo `LICENSE`) · no support, no warranty · **v1.0-prototype**. + +**One** UF2 for Raspberry Pi Pico (RP2040). Chip does air AFSK; Pico is **USB KISS half-TNC** (HDLC + bitbang to TCM3105 TXD/RXD) plus display / PTT / sense. + +| Owns | Does **not** | +|------|----------------| +| HDLC TX/RX (flags, bit-stuff, FCS-CCITT) | Softmodem / AFSK DSP | +| Bitbang GP6 TXD / GP7 RXD at crystal rate | Transparent Host↔Chip bit bridge | +| USB CDC: KISS `0xC0` + ASCII service | Baud switch / XTAL mux | +| Auto PTT GP9 during KISS TX · `PTT ON`/`OFF` | Dual baud UF2 builds | +| Display / INI texts · CDT Signal · packet sense · fixed boot banner | INI/CDC boot-banner toggle | + +## Build + +Requires [Pico SDK](https://github.com/raspberrypi/pico-sdk) and `arm-none-eabi-gcc`. + +```bash +export PICO_SDK_PATH=/path/to/pico-sdk # or repo .deps/pico-sdk +cd firmware/c1224 +mkdir -p build && cd build +cmake .. -DC1224_BITRATE=1200 # or 2400 if Y2 stuffed +make -j$(nproc) c1224 +# → c1224.uf2 c1224.elf +``` + +`C1224_BITRATE` must match the stuffed crystal (**Y1 4.4336 → 1200**, **Y2 6.5536 → 2400**). Default **1200**. Same source tree; rebuild if field board is 2400. + +### Flash + +1. Hold **BOOTSEL**, plug USB (Path B — flash/service; board power = **12 V** barrel). +2. Copy `c1224.uf2` to RPI-RP2 (or `picotool load -f c1224.uf2`). +3. Host opens `/dev/ttyACM*` (USB CDC). + +## Any KISS terminal (standalone — no MAX25) + +**MAX25-Stack is not required.** No proprietary host protocol. **All terminals should work insofar as applicable** — any client that speaks **KISS and/or ASCII service** over a raw serial port. Optional convenience only: max25d device **`tmodem`** / `max25-terminal`. + +How-to: flash UF2 → plug USB → open `/dev/ttyACM*` → KISS `0xC0` or ASCII `HELP`. + +| Step | Detail | +|------|--------| +| Device | `/dev/ttyACM*` (Linux) / equivalent CDC ACM | +| Framing | Raw **8N1** · binary **KISS** (`0xC0` … `0xC0`) · DATA cmd `0x00` | +| Packet path | Send/receive KISS frames only — do **not** interleave ASCII while mid-frame | +| Service path | Optional line ASCII (`STATUS`, `PTT`, …) when **not** inside a KISS frame | +| Boot | Fixed source banner **always** once after CDC ready · `quiet=1` damps extra STATUS/CONFIG ASCII only | + +Examples: **kissattach** / ax25 tools, **kissutil**, Dire Wolf serial KISS, custom terminal, or optionally **max25-terminal** via **`tmodem`**. + +```bash +# Example: open CDC raw and use KISS (tool-dependent) +# stty -F /dev/ttyACM0 raw -echo +# kissutil -p /dev/ttyACM0 +# # or: kissattach /dev/ttyACM0 tm0 (ax25-tools; names vary by distro) +``` + +## Dual protocol (USB CDC) + +| Traffic | Rule | +|---------|------| +| Packet | Bytes starting with / continuing **`0xC0` KISS** → HDLC TX / RX encode | +| Service | Line-oriented ASCII → `PTT`, `STATUS`, `INI`, … | +| Custom terminals | Prefer **KISS-only** for packet; service commands optional | + +## Host path (summary) + +| Traffic | Format | +|---------|--------| +| Packet | Binary **KISS** frames (`0xC0` … `0xC0`) — DATA cmd `0x00` | +| Service | Line ASCII: `PTT`, `STATUS`, `ID`, `QUIET`/`VERBOSE`, `INI` / `GET` / `SET` / `SAVE` | + +## Pins + +| GPIO / rail | Role | +|-------------|------| +| GP0 / GP1 | I2C LCD | +| GP6 | Modem **TXD** — HDLC bitbang out | +| GP7 | Modem **RXD** — HDLC bitbang in + Packet UI sense | +| GP8 | Modem **CDT** → Signal/RX | +| GP9 | **PTT** (auto on TX + manual CDC) | +| GP10–12 | Optional LEDs | +| — | LED_PWR on **5 V rail** | + +## Boot banner + +Fixed source text in `src/common/banner.c` / `include/version.h` (not INI / CDC). **Always** printed once after USB CDC ready. Edit source only — no `banner=` INI key, no `BANNER ON|OFF`. `quiet=1` never suppresses the boot banner (only extra STATUS/PROBE/CONFIG ASCII). + +## USB CDC ASCII + +| Command | Effect | +|---------|--------| +| `HELP` | Command list | +| `STATUS` | state, PTT, signal, packet, bitrate, raw CDT/RXD | +| `ID` | `device_id` / `callsign` / bitrate / quiet (solicited) | +| `PTT ON` / `PTT OFF` | Key GP9 | +| `QUIET ON` / `OFF` | Suppress extra unsolicited CDC ASCII (default ON via INI `quiet=1`; never the boot banner) | +| `VERBOSE ON` / `OFF` | Alias: `QUIET OFF` / `QUIET ON` | +| `INI` / `GET` / `SET` / `SAVE` / `RELOAD` / `DEFAULTS` | Config | + +**`SAVE`:** writes a config **blob** into the **last 4 KiB** of Pico flash — **not** a filesystem. + +## INI (`[terminal]`) + +| Key | Default | Role | +|-----|---------|------| +| `callsign` | empty | Operator call / station string for `ID` | +| `device_id` | `c1224` | Short device mark (`c1224` or `tmodem`) | +| `quiet` | `1` | Suppress extra unsolicited CDC ASCII (not boot banner) | + +Display text keys (`starting`, `ready`, …) and sense keys unchanged. See [`share/c1224.ini.example`](../../share/c1224.ini.example). + +## Rate + +Stuff **Y1 4.4336** (1200) or **Y2 6.5536** (2400). Firmware does not switch baud at runtime. Rebuild with `-DC1224_BITRATE=2400` for Y2 boards. |