Crate ados_crsf_codec 

ados-crsf-codec

no_std CRSF (Crossfire / ExpressLRS) codec: frames, packed RC channels, telemetry and parameter frames, axis scaling and link liveness.

CRSF is the serial protocol spoken by Crossfire and ExpressLRS radio modules, receivers and flight controllers. This crate encodes and decodes it: build an RC channels frame for a transmitter module, hunt frames out of a noisy byte stream, decode the telemetry a module sends back, and decide from link statistics whether the radio link is actually up. It is pure data handling with no I/O, so it runs the same on a microcontroller and on a Linux host.

use ados_crsf_codec::channels::{build_rc_frame, unpack_channels, CHANNEL_COUNT, CHANNEL_MID, PACKED_SIZE};
use ados_crsf_codec::frame::{Parser, ADDR_FLIGHT_CONTROLLER, TYPE_RC_CHANNELS_PACKED};

// 16 channels at center, with throttle low and one switch high.
let mut channels = [CHANNEL_MID; CHANNEL_COUNT];
channels[2] = 172;
channels[4] = 1811;

// One complete wire frame: sync, length, type, 22-byte payload, CRC-8.
let wire = build_rc_frame(&channels).unwrap();
assert_eq!(wire.len(), 26);

// Feed the bytes to the stream parser, split across two reads and
// preceded by line noise.
let mut parser = Parser::new();
assert!(parser.push(&[0x00, 0x42]).is_empty());
let mut frames = parser.push(&wire[..10]);
frames.extend(parser.push(&wire[10..]));
assert_eq!(frames.len(), 1);

let frame = &frames[0];
assert_eq!(frame.sync, ADDR_FLIGHT_CONTROLLER);
assert_eq!(frame.frame_type, TYPE_RC_CHANNELS_PACKED);
let payload: &[u8; PACKED_SIZE] = frame.payload.as_slice().try_into().unwrap();
assert_eq!(unpack_channels(payload), channels);

Highlights

• #![no_std] with alloc; zero dependencies. Builds for bare-metal targets such as thumbv7em-none-eabihf.
• The stream parser never panics on garbage: it resyncs byte by byte and counts the bytes it skipped.
• Codecs round-trip: every typed frame has an encoder and a decoder, and 61 unit tests check wire layouts and round trips.
• Payload sizes are validated against the frame type before decoding, so a short or long payload is an error, not a panic.
• Link liveness is a pure function: no clocks, no threads, just durations in and a state out.

How it works

The crate has seven modules.

• frame is the byte framing. Every frame is [sync] [len] [type] [payload...] [crc8]. len counts the bytes after it (type, payload and CRC, so 2..=62). The CRC-8 uses the DVB-S2 polynomial 0xD5 (init 0, no reflection, no xor-out) and covers the type and payload only. The sync byte is a device address: 0xC8 (flight controller), 0xEE (transmitter module) or 0xEA (radio handset); anything else is rejected. Parser buffers partial input and returns every complete, CRC-valid frame.
• channels packs 16 channels of 11 bits each, LSB first, into the 22-byte RC_CHANNELS_PACKED (0x16) payload. 172 is full low, 992 center and 1811 full high. The codec round-trips any 11-bit value; clamping to the usable range is the caller’s choice.
• bank is a validated set of 16 channel values: writes outside 172..=1811 are rejected, and a bulk write is all or nothing.
• scale maps a signed 16-bit axis onto the channel range (with an exact 992 center) and an N-position switch onto evenly spaced channel values.
• telemetry decodes and encodes link statistics (0x14), GPS (0x02), battery (0x08), attitude (0x1E) and flight mode (0x21). Multi-byte fields are big-endian.
• params carries the parameter protocol: read (0x2E), write (0x2F) and settings entry (0x2D) frames.
• link derives a link state from what was observed. Bytes accepted by a serial driver prove nothing about the radio, so the verdict keys on fresh link-statistics telemetry and its uplink link quality. Transmitting with no fresh statistics past a grace window, or with uplink quality at zero, reads RfUnverified; only LinkOk and Degraded count as flyable.

Part of ADOS

Used in production by the ADOS Drone Agent, the onboard software of the ADOS software-defined drone platform. All ADOS crates · Docs · Discord

Other ADOS crates

Platform (versioned with the ADOS Drone Agent)

Crate	What it does	Docs
ados-protocol	Wire contracts of the ADOS Drone Agent: IPC framing, plugin RPC envelope, capability tokens and the vision frame bus.	docs.rs
ados-sdk	Write Rust plugins for the ADOS Drone Agent: IPC client, plugin context, driver traits and lifecycle runner.	docs.rs
ados-vision	Single-object visual tracker: Kalman motion model, appearance re-identification and YOLOv8 head decoding.	docs.rs
ados-gpio	Drive status buzzers and LEDs on Linux GPIO lines, with bounded software-PWM beep patterns.	docs.rs
ados-hal-probe	Find out what a board’s hardware can really do by probing it, plus bundled board profiles.	docs.rs

Standalone

Crate	What it does	Docs
ados-sensorhub	Sensor hub wire protocol: COBS framing, CRC-16 and fixed-layout IMU, baro, mag and GNSS packets. no_std.	docs.rs
ados-offload	Choose where perception runs (onboard, offloaded or hybrid) and hold the vehicle when results go stale.	docs.rs
ados-macpin	Stable MAC addresses for Linux network adapters that randomize theirs every boot.	docs.rs
ados-lora	LoRa transmit governor with cited regional band plans, duty cycle, dwell time and airtime accounting.	docs.rs
ados-positioning	Split mixed UBX, NMEA and RTCM3 GNSS streams, configure u-blox receivers and run an RTK base survey-in.	docs.rs
ados-rtcm	RTCM3 framing, CRC-24Q and MAVLink GPS_RTCM_DATA fragmentation for RTK corrections.	docs.rs
ados-clock	Map remote clocks onto the host clock: least-squares and envelope fits, TIMESYNC and a chrony sink.	docs.rs
ados-swarm	Swarm control laws: separation, flocking, formations, CBBA task allocation and a point-mass simulator.	docs.rs
ados-mavlink-tunnel	Send large messages over MAVLink TUNNEL frames with chunking and bounded reassembly.	docs.rs
ados-display-driver	Small-display output on Linux: SSD1306/SH1106 OLED over I2C, pixel packers and a framebuffer writer.	docs.rs
ados-hmi	Front-panel input: touchscreen calibration and gestures, button presses and rotary encoders.	docs.rs

ADOS repositories

Repo	Runs on	What it does	Link
ADOS Mission Control	Browser, desktop (Electron)	Ground control station: FC setup, mission planning, flight, 3D simulation, fleet	ADOSMissionControl
ADOS Drone Agent	Companion computer on the drone, or a ground node	Onboard agent: MAVLink routing, HD video, long-range radio link, plugins, remote control	ADOSDroneAgent
ADOS Android GCS	Android phones and tablets	Native ground control app for agents on the LAN, direct flight controllers and the cloud	ADOSAndroidGCS
ADOS Extensions	Drone Agent and Mission Control	First-party signed plugins, each with an agent half and a GCS half	ADOSExtensions
ADOS MCP	Your machine	Model Context Protocol server that lets AI clients operate ADOS drones under scopes and a safety gate	ADOS-MCP
Documentation	docs.altnautica.com	Public docs for every ADOS product	Documentation

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this crate by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

Modules

bank

A validated bank of 16 RC channel values.

channels

RC channel packing: 16 channels × 11 bits, little-endian LSB-first, the payload of the RC_CHANNELS_PACKED (0x16) frame.

frame

CRSF frame layer: the byte framing, the CRC, and a sync-hunting stream parser that never panics on garbage.

link

Link state derivation: a pure function from observed inputs to a link state and an rf_unverified verdict.

params

Parameter (configuration) frame codecs: settings entry (0x2D), read request (0x2E), and write command (0x2F).

scale

Input scaling: signed 16-bit axis and switch values → CRSF channel values.

telemetry

Telemetry frame codecs: link statistics (0x14), GPS (0x02), battery (0x08), attitude (0x1E), and flight mode (0x21).