cel_crsf_channel_us_to_val() and cel_crsf_channel_val_to_us()
convert between microseconds (988-2012) and 11-bit values (172-1811)
with rounding. cel_crsf_channel_default() fills safe/disarmed values.
cel_crsf_frame_parse() parses ELRS USB format frames:
[addr][length][type][payload...][crc]
cel_crsf_stream_* provides incremental parsing from a byte
stream: skips invalid sync bytes, discards bad CRC frames,
buffers partial frames across feed calls.
The old [0xC8][dest][src][type][size][payload][crc] format was never
used with real hardware. Remove cel_crsf_frame_legacy, *_legacy()
functions, and update tests/tools accordingly.
Switch CRC from CCITT (0x07) to DVB-S2 (0xD5) to match ELRS.
Adopt ELRS USB frame format: [addr][length][type][payload][crc].
Update frame type constants to match current ELRS protocol values.
New skeleton modules (stub implementations with TODO comments):
- crsf_telemetry.h/.c: telemetry decoders (GPS, battery, link..)
- crsf_stream.h/.c: incremental streaming frame reader
- crsf_param.h/.c: parameter protocol (read/write/set_power)
Retained old frame format as *_legacy functions for backward
compatibility with existing telemetry tool and tests.
Add cel_serial_find_elrs_port() and cel_serial_open_probe()
stubs to serial module for port auto-detection and baud probing.
Add cel_serial_platform_open/close/read/write/flush for
Windows using CreateFileA, DCB for baud/8N1, and
SetCommTimeouts for non-blocking reads.
serial.c now delegates all operations to the platform
backend via a cel_serial_platform_handle, and
test_serial.c mocks that backend with CMock.
Drop timeout_ms; read now returns immediately with whatever
data is available (0 if none), so callers don't block the rest
of their loop waiting on serial I/O.
telemetry's poll loop now sleeps interval_ms itself between
empty reads via a small sleep_ms helper.
test_serial mocked log_write.h, which serial.c never calls.
Split celrs_serial into celrs_serial (platform-agnostic logic)
and celrs_serial_platform (real Win/POSIX backend), matching
the celrs_logger/celrs_log_write split.
test_serial now mocks celrs/platform/serial_internal.h and
links only celrs_serial, so the list-ports tests verify the
max_ports clamping and pass-through logic without hitting the
real registry or /dev.
Implement cel_serial_list_ports/cel_serial_free_ports with
platform backends: Windows reads HKLM\HARDWARE\DEVICEMAP\
SERIALCOMM (fast, single registry read), POSIX scans /dev for
ttyUSB*/ttyACM*.
telemetry tool gains --list, --port, and --baudrate flags;
baud rate was previously hardcoded to 400000. Rename the
tool_telemetry CMake target to telemetry.
Fix test_free_ports_zero_count, which passed a stack array to
cel_serial_free_ports (which calls free() on it), corrupting
the heap.
portersky