[ECU] Switch from TCP to serial interface

Author: AksonovSergei

docs/platform/ecu/protocol.md

@@ -1,26 +1,25 @@
 # Shassis Controller Communication Protocol
 
 ## 1. Overview
-This protocol is designed for communication between a ROS2 system running on platforms such as RPI and a chassis controller operating on hardware like BeagleBone Blue or STM32. It supports both TCP and UART, allowing for a seamless future transition between the two communication methods.
+This protocol is designed for communication between a ROS2 system running on platforms such as RPI and a chassis controller operating on hardware like BeagleBone Blue or STM32. It uses UART for communication.
 
 ## 2. Protocol Architecture
 The protocol consists of two layers:  
-1. **Frame Layer (Layer 1)** – Ensures data integrity, required only for UART.  
-2. **Protocol Layer (Layer 2)** – Defines the core communication commands.  
+1. **Data Link Layer** – Ensures data integrity.  
+2. **Application Layer** – Defines the core communication commands.  
 
-### 2.1. Frame Layer (Layer 1) – UART Only
-**(Not used in TCP mode)**  
-The frame layer is **only applicable when using UART**, as UART does not guarantee message integrity or completeness.
+### 2.1. Data Link Layer
+The Data Link Layer ensures message integrity and completeness.
 
-**Frame Format (UART Only)**
+**Frame Format**
 | Offset | Size (bytes) | Field         | Description |
 |--------|-------------|---------------|-------------|
-| 0      | 1           | `frame_length` | Total packet length (including CRC16). Ensures packet boundary detection over UART |
-| 1      | N           | `payload`      | Protocol Layer (Layer 2) data |
-| N+1    | 2           | `crc16`        | CRC16 checksum. Provides error detection for unreliable UART communication |
+| 0      | 1           | `frame_length` | Total packet length including CRC16. |
+| 1      | N           | `payload`      | Application Layer (Layer 2) data. |
+| N+1    | 2           | `crc16`        | CRC16 checksum (Modbus polynomial: 0x8005). |
 
-### 2.2 Protocol Layer (Layer 2) – Used in TCP & UART
-This is the core protocol used in both TCP and UART modes. 
+### 2.2 Application Layer
+This layer defines the structure of the commands and responses.
 
 **Protocol Format**
 | Offset | Size (bytes) | Field         | Description |
@@ -36,7 +35,7 @@ This is the core protocol used in both TCP and UART modes.
 | `0x03`     | [`set_all_motors_speed`](#set_all_motors_speed-0x03) | Sets the speed for all four motors in a single command |
 | `0x04`     | [`get_encoder`](#get_encoder-0x04) | Retrieves the encoder value for a specific motor |
 | `0x05`     | [`get_all_encoders`](#get_all_encoders-0x05) | Retrieves the encoder values for all motors |
-| `0x06`     | [`connect_udp`](#connect_udp-0x06) | Connects to UDP port and starts sending odometry data |
+| `0x06`     | [`get_imu`](#get_imu-0x06) | Retrieves IMU data (accelerometer, gyroscope, quaternion, magnetometer) |
 
 ### get_api_version (0x01)
 Retrieves the firmware/API version.
@@ -67,6 +66,7 @@ Sets the speed of a specific motor.
 | Offset | Size (bytes) | Field Description | Values |
 |--------|-------------|------------------|--------|
 | 0      | 1           | command_id       | 0x02   |
+| 1      | 1           | status           | 0 = OK, 1 = Error |
 
 ### set_all_motors_speed (0x03)
 Sets the speed for all four motors in a single command.
@@ -84,6 +84,7 @@ Sets the speed for all four motors in a single command.
 | Offset | Size (bytes) | Field Description | Values |
 |--------|-------------|------------------|--------|
 | 0      | 1           | command_id       | 0x03   |
+| 1      | 1           | status           | 0 = OK, 1 = Error |
 
 ### get_encoder (0x04)
 Retrieves the encoder value for a specific motor.
@@ -117,37 +118,28 @@ Retrieves the encoder values for all motors.
 | 9      | 4           | encoder_value_motor_3 | Encoder value (signed value, negative value means reverse direction) |
 | 13     | 4           | encoder_value_motor_4 | Encoder value (signed value, negative value means reverse direction) |
 
-### connect_udp (0x06)
-Connects to a UDP port and starts sending odometry/IMU data. The ECU will send UDP packets to the client's IP address and the specified port.
+### get_imu (0x06)
 
 **Request**
 | Offset | Size (bytes) | Field Description | Values |
-|--------|-------------|------------------|--------|
-| 0      | 1           | command_id       | 0x06   |
-| 1      | 4           | port             | UDP port number for odometry data transmission |
+|--------|--------------|-------------------|--------|
+| 0      | 1            | command_id        | 0x06   |
 
 **Response**
-| Offset | Size (bytes) | Field Description | Values |
-|--------|-------------|------------------|--------|
-| 0      | 1           | command_id       | 0x06   |
-| 1      | 1           | status           | 1 = OK, 0 = Error |
-
-## 4. UDP Data Format
-When connected via UDP (after sending `connect_udp` command), the ECU sends IMU/odometry data packets to the client's IP address and specified port.
-
-**UDP Packet Format**
 | Offset | Size (bytes) | Field Description | Values/Format |
-|--------|-------------|------------------|---------------|
-| 0      | 1           | imu_id           | IMU sensor ID (uint8_t) |
-| 1      | 2           | packet_number    | Packet sequence number (uint16_t, big-endian) |
-| 3      | 4           | accel_x          | Accelerometer X-axis (float, big-endian) |
-| 7      | 4           | accel_y          | Accelerometer Y-axis (float, big-endian) |
-| 11     | 4           | accel_z          | Accelerometer Z-axis (float, big-endian) |
-| 15     | 4           | gyro_x           | Gyroscope X-axis (float, big-endian) |
-| 19     | 4           | gyro_y           | Gyroscope Y-axis (float, big-endian) |
-| 23     | 4           | gyro_z           | Gyroscope Z-axis (float, big-endian) |
-| 27     | 4           | quat_w           | Quaternion W component (float, big-endian) |
-| 31     | 4           | quat_x           | Quaternion X component (float, big-endian) |
-| 35     | 4           | quat_y           | Quaternion Y component (float, big-endian) |
-| 39     | 4           | quat_z           | Quaternion Z component (float, big-endian) |
+|--------|-------------|--------------------|---------------|
+| 0      | 1           | command_id         | 0x06 |
+| 1      | 4           | accel_x            | Accelerometer X-axis (float, little-endian) |
+| 5      | 4           | accel_y            | Accelerometer Y-axis (float, little-endian) |
+| 9      | 4           | accel_z            | Accelerometer Z-axis (float, little-endian) |
+| 13     | 4           | gyro_x             | Gyroscope X-axis (float, little-endian) |
+| 17     | 4           | gyro_y             | Gyroscope Y-axis (float, little-endian) |
+| 21     | 4           | gyro_z             | Gyroscope Z-axis (float, little-endian) |
+| 25     | 4           | mag_x              | Magnetometer X-axis (float, little-endian) |
+| 29     | 4           | mag_y              | Magnetometer Y-axis (float, little-endian) |
+| 33     | 4           | mag_z              | Magnetometer Z-axis (float, little-endian) |
+| 37     | 4           | quat_w             | Quaternion W component (float, little-endian) |
+| 41     | 4           | quat_x             | Quaternion X component (float, little-endian) |
+| 45     | 4           | quat_y             | Quaternion Y component (float, little-endian) |
+| 49     | 4           | quat_z             | Quaternion Z component (float, little-endian) |