* Add KISS TNC external app for APRS RX/TX over USB serial
Adds a KISS TNC (Terminal Node Controller) app that bridges APRS
packets between the HackRF radio and a connected PC over USB CDC
serial using the KISS protocol.
Features:
- APRS receive at 144.390 MHz (configurable), decoding packets via
the existing APRS RX baseband (PAPR.bin)
- Received AX.25 frames forwarded to host as KISS-framed data over
USB serial
- KISS frames received from host transmitted as AFSK audio using the
existing AFSK TX baseband (PAFT.bin)
- Clean RX->TX->RX baseband switching with proper timing delays
- USB connection status indicator with periodic refresh
- Compatible with standard KISS TNC clients (Xastir, APRSISCE/32,
Dire Wolf, etc.)
Firmware changes required to support the external app:
- baseband_api.cpp: mark set_aprs() __attribute__((used)) so it is
retained by the linker for external app use
- protocols/ax25: add make_frame_from_raw() to build NRZI bitstream
from raw AX.25 bytes, marked __attribute__((used))
- usb_serial_host_to_device: add kiss_raw_handler hook to route
incoming USB bytes directly to a registered callback, bypassing
the shell; marked __attribute__((used))
- baseband/proc_aprsrx: add constructor that auto-configures at
1200 baud so external apps do not need to call set_aprs() at init
* Address PR review: generic RAII USB handler, fix TX cutoff and buffer overflow
- Replace KISS-specific set_kiss_raw_handler() in shared USB code with a
generic UsbSerialInputHandler RAII class; any app can now register a
handler via the ctor and it auto-clears in the dtor — no app-specific
'if' checks in shared code, no __attribute__((used)) needed
- Remove __attribute__((used)) from set_aprs() — it is referenced directly
by ui_aprs_rx.cpp so it will never be dead-stripped
- Fix send_kiss_frame() buffer overflow: per-byte bounds check prevents
2-byte escape sequences from writing past the end of the output buffer
- Replace fillOBuffer(TIME_INFINITE) with chOQWriteTimeout(TIME_IMMEDIATE)
to drop bytes instead of blocking the event loop
- Remove chThdSleepMilliseconds() calls from start_tx() and finish_tx()
- Fix TX cutoff bug: call start_tx() directly from process_kiss_frame()
instead of deferring via tx_pending_ flag (deferral caused kiss_idx_
to be 0 by the time start_tx() fired, producing an empty frame)
* Move USB write into UsbSerialInputHandler class
Add a write() method to UsbSerialInputHandler so all USB I/O
(both input callback and output) is encapsulated in the class.
KISS TNC now uses usb_input_handler_->write() instead of calling
chOQWriteTimeout(&SUSBD1.oqueue, ...) directly, keeping raw USB
details out of app code.
* Address PR review: remove auto-configure from APRSRxProcessor, add timeout param to write()
- Remove default_config from APRSRxProcessor() constructor; baseband should
start unconfigured and wait for APRSRxConfigureMessage from the app side
(already sent via baseband::set_aprs() in KISS TNC and APRS RX app)
- Remove stray #include "stdio.h" from proc_aprsrx.cpp
- Add systime_t timeout parameter with default TIME_IMMEDIATE to
UsbSerialInputHandler::write() so callers can choose blocking behaviour
Sarah Rose
Bernd Herzog