cel_crsf_build_rc_frame tagged RC channel frames with 0x01,
which is not a valid CRSF frame type. The TX module's CRSF
parser never recognized these as channel updates, so it had
no RC data to forward over RF and the receiver could never
report link quality.
Use CEL_CRSF_TYPE_RC_CHANNELS (0x16), the spec-correct RC
Channels Packed type. Drop the bogus 0x01 enum value.
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.
portersky