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README.md

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TODO

  • Optimize measurements so all the data is stored ONLY in system variable.
  • Add second IMU
  • Add filtering to IMU data
  • Add depth sensing
  • Test control loops
  • Add packet for telemetry setup
  • Allow multiple telemetry links
  • Add tasks stats to system variables
  • Reorganize control loop so info about used PID controlers, variables etc can be stored in configuration file
  • Implementation of EKF

Comunication protocol

Each message sended from and to TCM must follow protocol described in this section. The bit order is LSB first.

Packet structure

Byte name value/length
Header 0 0x69
Header 1 0x68
Payload length byte
Message type byte
Payload 0 - 500
Checksum MSB byte
Checksum LSB byte

Checksum calculation

Cheksum is 16-bit CRC-CCITT. It is calculated with following function:


uint16_t calculateChecksum(uint8_t* data_p, uint16_t length)
{
    uint8_t x;
    uint16_t crc = 0xFFFF;

    while (length--){
        x = crc >> 8 ^ *data_p++;
        x ^= x>>4;
        crc = (crc << 8) ^ ((uint16_t)(x << 12)) ^ ((uint16_t)(x <<5)) ^ ((uint16_t)x);
    }
    return crc;
}

Message types

They are few types of message that you can send or receive with TCM. If the payload is not described it means that it length is 0.

Message types to TCM

Type value
Request 0x0
Service 0x1
Control 0x2

Request message

User can request data from TCM.

Type value Service mode required
PID 0x0 No
Control matrix 0x1 Yes
Data 0x2 No

Service message

These messages are used to test, set, load and save new settings.

Type value Service mode required
Enter service mode 0x0 No
Reboot 0x1 Yes
Enable direct thrusters ctrl 0x2 Yes
Disable direct thrusters ctrl 0x3 Yes
Direct motors ctrl 0x4 Yes
Direct motors ctrl via matrix 0x5 Yes
Save settings 0x6 Yes
Load settings from flash 0x7 Yes
New PID values 0x8 No

Control message

The only option to control the boat is using sticks. Stick values are float big endian. It is possible but not mandatory to send up to 16 stick commands in one message.

For now sticks are corresponding to the control inputs as follow:

- stick 0 - roll
- stick 1 - pitch
- stick 2 - yaw
- stick 3 - vertical
- stick 4 - forward
- stick 5 - enable thrusters

Example message for commanding the sticks:

Byte name value/length
Header 0 0x69
Header 1 0x68
Payload length (20) MSB byte
Payload length (20) LSB byte
0x2 - ctrl msg byte
stick 0 4 bytes (float)
stick 1 4 bytes (float)
stick 2 4 bytes (float)
stick 3 4 bytes (float)
stick 4 4 bytes (float)

|Checksum MSB|byte| |Checksum LSB|byte|

Message types from TCM

Type value
PID 0x3
Control matrix 0x4
Heart beat 0x5
Service confirm 0x6
Telemetry 0x7
Variable 0x8

PID

Heart beat

TCM is sending heart beat packet twice a second.

Service confirm

After each service message received TCM is responding with this packet.

Telemetry

Compiling

  • Copy following lines to install vcpkg:

  • Clone TMC code from github

  • Open TMC folder with VSCode

  • Install Embeded Tools extension

  • Install CMake Tools extension

  • in terminal type vcpkg activate

Thats it.