XGO Serial Protocol

1. Overview

This document defines the command and data interaction protocol between an external host (PC, Raspberry Pi, Arduino, etc.) and the XGO series robot drive board. It is intended for advanced developers performing secondary development on the XGO platform.

1.1 Physical Layer (Hardware Interface)

Interface: Standard TTL Serial

Baud Rate: 115200 bps

Data Bits: 8

Stop Bits: 1

Parity: None

1.2 Data Frame Format

XGO uses a fixed-structure data frame to ensure reliability.

Field	Header	Length	Data	Checksum	Footer
Size (Bytes)	2	1	Variable	1	2
Value	0x55 0x00	Total Frame Size	See Instruction Types	Calculated	0x00 0xAA

Checksum Calculation: Sum all bytes of Length and Data, take the lowest byte (LOB), then perform a bitwise NOT operation (~).

Timing Requirement: It is recommended to maintain at least a 1ms interval between consecutive commands to prevent packet loss.

2. Instruction Types

2.1 Write Command (0x00) - No Response

Used to modify data starting from a specific address. No feedback is returned by the robot.

Example: Set Forward Speed to Maximum

Address:0x30 | Value:0xFF (Max)

Calculation:0x09 (Len) + 0x00 (Type) + 0x30 (Addr) + 0xFF (Val) = 0x138. LOB = 0x38. Bitwise NOT = 0xC7.

Frame:55 00 09 00 30 FF C7 00 AA

2.2 Read Command (0x02) - With Response

Used to query a sequence of data starting from a specific address.

Example: Read 12 Servo Angles

Address:0x50 | Length to Read:12 (0x0C)

Frame:55 00 09 02 50 0C 98 00 AA

Response Packet:55 00 14 12 50 [12 Bytes of Data] [Checksum] 00 AA

3. Coordinate Systems & Numbering

3.1 Robot Body Coordinate System

Origin: Directly beneath the center of the body at default standing height.

X-Axis: Positive forward.

Y-Axis: Positive to the left.

Z-Axis: Positive upward.

3.2 Single Leg Coordinate System

Each of the four legs has its own local coordinate system.

Origin: The hip joint.

x-axis: Positive forward.

y-axis: Positive to the left.

z-axis: Positive downward.

3.3 Servo ID Mapping

Each leg consists of three joints: Shoulder (3), Upper Arm (2), and Lower Arm (1).

Leg Position	Shoulder (3)	Upper Arm (2)	Lower Arm (1)
Front Left (1)	13	12	11
Front Right (2)	23	22	21
Back Right (3)	33	32	31
Back Left (4)	43	42	41

4. Register Map (Memory Table)

The robot's internal state and control parameters are mapped to specific register addresses.

Data Range: Most values range from 0x00 to 0xFF.

Neutral Point: For movement and position registers, 0x80 typically represents the neutral/center position or zero offset.

4.1 System & Mode Settings

Address	Function	R/W	Initial	Description
0x00	Work Status	R	0x00	System status information.
0x01	Battery Level	R	0xff	0-100 (Linear mapping from min to max voltage).
0x03	Performance Mode	W	0x00	0x00 : Normal; 0x01 : Loop all actions; 0x02 : Loop actions (no movement).
0x04	Calibration Mode	W	0x00	0x01 : Enter Calibration; 0x00 : Exit and save.
0x05	Firmware Update	W	0x00	0x01 : Enter update mode. Controller will echo the command before flashing.
0x06	Set Origin	W	-	0x01 : Set current heading as 0°.
0x07	Firmware Version	R	-	Returns a 10-byte string.
0x09	Gait Selection	W	0x00	0x00 : TROT; 0x01 : WALK; 0x02 : HIGH WALK.
0x20	Servo Torque	R/W	0x00	0x00 : Torque ON; 0x01 : Unload all; 0x11-14 : Unload Leg 1-4.

4.2 Whole-Body Movement Control

Address	Function	R/W	Initial	Description
0x30	Longitudinal Velocity	R/W	0x80	X-axis speed: 0x00 (Back) to 0xFF (Forward).
0x31	Lateral Velocity	R/W	0x80	Y-axis speed: 0x00 (Right) to 0xFF (Left).
0x32	Rotational Velocity	R/W	0x80	Yaw speed: 0x00 (CW) to 0xFF (CCW).
0x33	Body X-Translation	R/W	0x80	Body shift along X-axis (feet fixed).
0x34	Body Y-Translation	R/W	0x80	Body shift along Y-axis (feet fixed).
0x35	Body Height	R/W	0x80	Body height (Z-axis).
0x36	Body Roll Angle	R/W	0x80	Rotation around X-axis.
0x37	Body Pitch Angle	R/W	0x80	Rotation around Y-axis.
0x38	Body Yaw Angle	R/W	0x80	Rotation around Z-axis.
0x3C	Mark Time (Stepping)	R/W	0x00	0x01-0xFF : Min to Max stepping height.
0x3D	Speed Profile	R/W	0x00	0x00 : Normal; 0x01 : Slow; 0x02 : High Speed.
0x3E	Action Command	W	0x00	Trigger Action ID (see Action Table). 255 : Reset Pose.

4.3 Inverse Kinematics (IK) - Single Leg Mode

Address	Function	R/W	Address	Function	R/W
0x40	Leg 1 (FL) - X	R/W	0x46	Leg 3 (BR) - X	R/W
0x41	Leg 1 (FL) - Y	R/W	0x47	Leg 3 (BR) - Y	R/W
0x42	Leg 1 (FL) - Z	R/W	0x48	Leg 3 (BR) - Z	R/W
0x43	Leg 2 (FR) - X	R/W	0x49	Leg 4 (BL) - X	R/W
0x44	Leg 2 (FR) - Y	R/W	0x4A	Leg 4 (BL) - Y	R/W
0x45	Leg 2 (FR) - Z	R/W	0x4B	Leg 4 (BL) - Z	R/W

4.4 Servo Direct Control

Address	Servo ID	Description	Address	Servo ID	Description
0x50	11	FL Lower Arm	0x56	31	BR Lower Arm
0x51	12	FL Upper Arm	0x57	32	BR Upper Arm
0x52	13	FL Shoulder	0x58	33	BR Shoulder
0x5C	Speed	Global Servo Speed (Servo Mode only)	0x5D/E	52/53	Robotic Arm Servos

4.5 IMU & Robotic Arm

Address	Function	R/W	Description
0x60	YAW Calibration	W	Write 0x01 while static to calibrate (approx. 5s).
0x61	IMU Stabilization	R/W	0x00 : OFF; 0x01 : Self-stabilization mode.
0x62-64	IMU Angles (Float)	R	Read Roll, Pitch, Yaw in Float format.
0x66-68	IMU Angles (Short)	R	Read Roll, Pitch, Yaw in Int16 format.
0x71	Gripper Status	W	0x00 to 0xFF (Fully Open to Fully Closed).
0x73/74	Gripper X / Z	W	Coordinate control for the end-effector.

4.6 Peripherals (LED & IO)

Address	Function	R/W	Description
0x69	LED 1 Color	W	Write 3 bytes [R, G, B]. Range: 0-255.
0x6A	LED 2 Color	W	Same as above.
0x6B	LED 3 Color	W	Same as above.
0x90	2-Pin 5V Out	W	0 : OFF; 1 : ON (High level).
0x91	Digital IO Out	W	0 : OFF; 1 : ON (Solenoid valve control).
0x92	Analog Read	R	Returns 1-byte value (0-255).
0x93	Digital Read	R	Returns 1-byte value (0 or 1).

5. Built-in Action Library (Preset Motions)

The robot features a library of pre-programmed actions. These motions can be interrupted by sending new movement or position commands.

Feedback: The robot does not send an "action complete" signal. It is recommended to implement a manual delay in your code based on the "Duration" column before sending the next comman

5.1 Basic Postures & Movements

ID (Dec)	Action Name	Duration (s)	Description
1	Lie Down	3	Robot transitions to a prone position.
2	Stand Up	3	Robot returns to the default standing pose.
3	Crawl	5	Low-profile forward movement.
4	Turn Around	5	Robot performs a 360-degree rotation.
6	Squat	4	Vertical up-and-down squatting motion.
144	Climb Stairs	12	Optimized gait for ascending/descending stairs.
255	Reset Pose	1	Immediate recovery to default neutral stance.

5.2 Body Rotation & Articulation

ID (Dec)	Action Name	Duration (s)	Description
7	Roll Rotation	4	Dynamic rotation around the X-axis.
8	Pitch Rotation	4	Dynamic rotation around the Y-axis.
9	Yaw Rotation	4	Dynamic rotation around the Z-axis.
10	3-Axis Rotation	7	Combined rotation of Roll, Pitch, and Yaw.

5.3 Interactive & Life-like Behaviors

ID (Dec)	Action Name	Duration (s)	ID (Dec)	Action Name	Duration (s)
11	Mark Territory (Pee)	7	18	Search for Food	6
12	Sit	5	19	Handshake	10
13	Wave Hand	7	20	Chicken Head	9
14	Stretch	10	21	Push-ups	8
15	Body Wave	6	22	Look Around	7
16	Swing Side-to-Side	6	23	Dance	6
17	Beg for Food	4	24	Naughty/Playful	7

5.4 Robotic Arm Actions (For Arm-Equipped Models)

ID (Dec)	Action Name	Duration (s)	Description
128	High Grab	10	Targeted grab at a high elevation.
129	Mid Grab	10	Targeted grab at a medium elevation.
130	Low Grab	10	Targeted grab at ground level.

6 XGO Rider (Bipedal-Wheel) Specific Register Map

The Rider series utilizes a specialized memory map to handle balancing, wheel odometry, and unique bipedal behaviors.

6.1 System & Communication Settings

Address	Function	R/W	Initial	Description
0x0A	Static Heading Lock	W	0x01	0x01 : Enable (Maintains current orientation when pushed).
0x30	Longitudinal Speed	W	0x80	0x00 (Reverse) to 0xFF (Forward).
0x32	Rotational Speed	W	0x80	0x00 (CW) to 0xFF (CCW).
0x35	Chassis Height	W	0x80	Adjusts the height of the bipedal legs.
0x61	Roll Balance Mode	W	0x00	0x00 : OFF; 0x01 : Self-Stabilization enabled.

6.2 Telemetry & IMU Data (6-Axis)

Address	Function	R/W	Format	Description
0x62-64	Euler Angles (Float)	R	Float	Roll, Pitch, and Yaw in floating point.
0x65	IMU 6-Axis Data	R	Float*6	24-byte packet containing raw IMU data.
0x66-68	Euler Angles (Short)	R	Int16	Roll, Pitch, and Yaw in 16-bit integer format.

6.3 Periodic Motions & Indicators

Address	Function	R/W	Initial	Description
0x39	Periodic Roll Swing	W	0x00	0x01-0xFF : Cycle speed for side-to-side body sway.
0x82	Periodic Z-Translation	W	0x00	0x01-0xFF : Cycle speed for up-and-down "bounce" motion.
0x3E	Action Command	W	0x00	Trigger preset Rider actions (see Rider Action Table).
0x69-6C	LED Colors (1-4)	W	[0,0,0]	Write 3 bytes [R, G, B] per LED to set colors.

6.4 XGO Rider Action Library (Preset Motions)

ID (Dec)	Action Name (English)	Description
1	Side-to-Side Sway	The robot oscillates its body laterally while maintaining balance.
2	Rhythmic Undulation	A vertical "up-and-down" motion resembling waves.
3	Forward-Backward Tilt	Controlled pitching motion moving the body front and back.
4	Square S-Curve	A complex "snake-like" movement following a square-wave path.
5	Rising Rotation	The robot changes its height while simultaneously spinning.
6	Circular Orbit	The body performs a circular "hula" or orbital shaking motion.
255	Reset Pose	Stops the current action and returns to the default balance state.