ATOM link (WiFi)

The laptop talks to the controller firmware over WiFi with UDP. All values are little-endian.

Port	Direction	Content
5006	laptop → ATOM	Commands
5007	ATOM → laptop	Replies and telemetry, sent to the address of the last command
5005	ATOM → broadcast	Status log, one text line per second

Messages

From 4.2 the same messages also go over a WebSocket (ws://<ATOM>/ws), and commands that move the robot need control; see the WebSocket API and the changelog.

Code	Message	Content	Reply
`0x01`	PING	—	`0x81` PONG: u16 version, u8 state, u32 plan samples, u16 plan rate, u8 IMU ok, u8 gains ok (3.0+), u8 minor, u8 patch (3.1+)
`0x02`	STATE	—	`0x82` STATE: u8 ok, u16 position[6], u16 speed[6], u16 load[6], i16 acc[3], i16 gyro[3]
`0x03`	HOLD	—	`0x83` ACK
`0x04`	PLAN_BEGIN	u32 samples, u16 rate (Hz), optional u8 interpolation (0 linear, 1 cubic; 3.1+)	ACK (`-3` = not enough memory)
`0x05`	PLAN_DATA	u32 offset, u16 count, count × {u16 cmd[6], u16 ref[6]}	ACK with the offset
`0x06`	PLAN_END	u32 CRC-32C of all samples	ACK (`-1` = CRC mismatch)
`0x07`	PLAY	u16 rate (Hz), u16 speed cap, u16 max error (steps), u16 start tolerance (steps)	ACK, then TELEM packets, then DONE
`0x08`	STOP	—	ACK
`0x09`	REG_READ (v3+)	u8 servo id (1–7), u8 address, u8 length (1–32)	`0x86`: u8 id, u8 address, u8 length, i8 status, data
`0x0A`	REG_WRITE (v3+)	u8 servo id, u8 address, u8 length, data	`0x87`: u8 id, u8 address, i8 status, u8 servo error
`0x0B`	PLAY_SIGNAL (3.1+)	the PLAY parameters, then `sig::Params` (38 bytes: u8 joint, u8 kind, f32 amp, f0, f1, duration, vmax, amax, i16 base[6] in 0.01°)	ACK (−11…−18 invalid parameters, −29/−30 bad start pose), then TELEM and DONE
`0x0D`	CONTROL (4.2+)	u8 action: 0 release, 1 take, 2 take over	ACK: 0, −2 another client has control, −1 robot moving
`0x0E`	MOVE_TO (4.2+)	i16 goal[6] (0.01°), u16 duration (ms, 0 = shortest)	ACK, TELEM, DONE
`0x0F`	JOG (4.2+)	u8 frame (0 = joints), i16 velocity[6] (0.1°/s); 200 ms deadman	ACK only if refused
`0x10`	TRACK (4.4+)	i16 goal[6] (0.01°), u16 vmax (0.1°/s, ≤ 90 °/s); 200 ms deadman	ACK only if refused
`0x0C`	SUBSCRIBE (4.1+)	u16 rate (Hz, 1–100; 0 = stop), renew at least once a second	`0x88` STREAM packets to the sender; see Clients

REG_READ and REG_WRITE are refused while a plan plays. The ATOM reads every write back. It refuses writes to registers 0–8 (ID, baud rate and other comms settings), 55 (EEPROM lock) and 80+ (factory). Status: 0 ok, −1 busy or bad request, −4 no reply, −5 not allowed, −6 the read-back differs. Writes to the EEPROM area last until the next power cycle. | 0x84 | TELEM | u32 first sequence number, u8 n, n × sample | — | | 0x85 | DONE | u8 result, u32 cycles, u32 max period (µs), u32 late cycles, u32 telemetry dropped, u8 joint, i16 error (steps) | — |

ACK (0x83) is: u8 message code, i8 status (0 = OK), u32 value.

Plans

A plan is a list of samples at a fixed rate (250 Hz by default). Each sample has two sets of six servo positions, in steps:

cmd: the goals the ATOM sends (lag-compensated or learned).
ref: the wanted positions. The ATOM uses them for the start check and the tracking check.

The ATOM interpolates linearly between samples at the control rate. The circle (15 s) is 3751 samples, about 90 KB.

Telemetry sample (53 bytes)

u32 t_us, u16 position[6], u16 speed[6], u16 load[6], i16 acc[3], i16 gyro[3], u8 ok

The values are raw register values. src/atom.jl converts them to degrees, °/s, %, g and °/s. The ATOM sends 20 samples per packet.

DONE results

Code	Result
0	done
1	tracking error (the ATOM holds the pose)
2	stopped (STOP received)
3	not at the start pose
4	bus error

Telemetry sample (4.0+)

77 bytes: u32 t_us, u16 cmd[6], u16 ref[6], u16 pos[6], u16 speed[6], u16 load[6], i16 acc[3], i16 gyro[3], u8 ok. Up to 18 samples per TELEM packet. Firmware before 4.0 sent 53-byte samples without cmd and ref; decode_telemetry reads both.

Julia API

import MyCobot
link = MyCobot.AtomLink("192.168.1.107")
MyCobot.atom_ping(link)                     # version, state, plan, IMU
s = MyCobot.atom_state(link)                # q (°), dq (°/s), load (%), imu (g, °/s)
MyCobot.atom_move_to(link, zeros(6))        # MOVES THE ROBOT: minimum-jerk move
rec, done = MyCobot.atom_play_trajectory(link, t, q_plan)   # MOVES THE ROBOT
MyCobot.write_atom_recording_csv("rec.csv", rec)
MyCobot.atom_read_reg(link, 1, 62, 2)       # servo 1: voltage (0.1 V), temperature (°C)
MyCobot.atom_write_reg(link, 1, 21, [32, 4, 16])   # servo 1: P, D, I
MyCobot.atom_gains(link)                    # (P, D, I) of the six servos
MyCobot.atom_set_gains!(link, MyCobot.GAINS)
rec, done = MyCobot.atom_play_signal(link, MyCobot.SignalParams(1, "chirp"; amp=10.0))   # MOVES THE ROBOT
close(link)

atom_play_trajectory has the same contract as the laptop player: it checks the plan, applies lag compensation (or uses q_cmd), uploads, plays and returns the recording with the IMU columns acc_x … gyro_z.