Welcome to the AresPayload wiki!

Update: Dec 19, 2025
Author: Mann Patel
Note: Documentation reflects the Osiris Payload

Table of Contents

1. Ares Payload
2. System Architecture
3. Data Flow
4. Task Details
5. State Machine Details
6. Communication Interfaces
7. Getting Started
8. Example Usage
9. Key Design Patterns
10. Development Notes
11. Hardware Naming Convention
12. Future Enhancements

Overview

The Osiris Payload System is an embedded flight computer designed for rocket payloads. It runs on an STM32H7 microcontroller using FreeRTOS and manages sensor data collection, state transitions, and hardware control throughout a rocket's flight.

System Architecture

High-Level Design

The system follows a task-based architecture using FreeRTOS, where different subsystems run as independent tasks that communicate via command queues. A state machine manages the flight phases and controls hardware accordingly.

Core Components

Sensors are named after Nintendo characters (God knows why?) :(

1. Mario & Luigi: LPS22HH barometer
2. Bowser: MS5611 barometer
3. Toopy & Binoo: LSM6DSO IMUs

1. Task System

The system uses multiple FreeRTOS tasks that run concurrently:

2. State Machine (OsirisSM)

The flight computer transitions through 5 states during operation:

PRELAUNCH -> LAUNCH -> DROGUE -> MAIN -> POSTLAUNCH

Each state controls different hardware peripherals and responds to different commands.

3. Sensor Drivers

Barometers

• LPS22HH (x2): "Mario" and "Luigi" - SPI-based pressure/temperature sensors
• MS5611 ("Bowser"): I2C-based pressure/temperature sensor

IMU (Inertial Measurement Unit)

• LSM6DSO (x2): "Toopy" (I2C) and "Binoo" (SPI) - Accelerometer and gyroscope sensors

4. Hardware Control (GPIO)

The system controls various hardware via GPIO pins:

• SOL1, SOL2, SOL3: Solenoid valves
• COMPRESSOR: Air compressor control
• LED_GREEN, LED_BLUE: Status indicators

Data Flow

Command Structure

Tasks communicate using a Command object with:

• Command Type: REQUEST_COMMAND, DATA_COMMAND, CONTROL_ACTION, etc.
• Task Command: Specific action identifier
• Data Payload: Optional data (e.g., sensor readings)

Data Structures

typedef struct BarometerData {
    float marioPressure;        // LPS22HH U3
    float marioTemperature;
    float luigiPressure;        // LPS22HH U4
    float luigiTemperature;
    uint32_t bowserPressure;    // MS5611
    uint32_t bowserTemperature;
} BarometerData;

typedef struct IMUData {
    float xAccel;
    float yAccel;
    float zAccel;
} IMUData;

Task Details

FlightTask

• Purpose: Coordinates overall flight logic
• Key Responsibility: Manages the OsirisSM state machine
• Communication: Receives data from IMUTask and BaroTask

IMUTask

• Purpose: Reads acceleration and gyroscope data
• Sensors: LSM6DSO (Toopy on I2C, Binoo on SPI)
• Commands:
  • IMU_REQUEST_LIN_ACC: Request linear acceleration
  • IMU_REQUEST_ANG_ACC: Request angular acceleration
• Output: Sends IMUData to FlightTask

BaroTask

• Purpose: Reads pressure and temperature data
• Sensors:
  • LPS22HH (Mario and Luigi on SPI)
  • MS5611 (Bowser on I2C)
• Commands:
  • BARO_REQUEST_NEW_SAMPLE: Read all sensors
  • BARO_REQUEST_DEBUG: Print sensor values
  • BARO_REQUEST_FLASH_LOG: Log data to flash memory
• Output: Sends BarometerData to FlightTask

DebugTask

• Purpose: Handles UART debug output
• Interface: USART6 (accessible via Driver::uart6)

State Machine Details

State Transitions

State Behaviors

PRELAUNCH

• Hardware: All peripherals OFF (safe state)
• Control: Can control SOL1, SOL2, SOL3, and COMPRESSOR
• LED: Green LED ON
• Purpose: Ground operations and testing

LAUNCH

• Hardware: All peripherals OFF
• Purpose: Rocket is ascending
• Transitions to: DROGUE (typically at apogee)

DROGUE

• Hardware: Can control SOL1, SOL2, SOL3, and COMPRESSOR
• Purpose: Drogue parachute deployed, descending
• Transitions to: MAIN (at specific altitude)

MAIN

• Hardware: Can control SOL3 and COMPRESSOR only
• Purpose: Main parachute deployed
• Transitions to: POSTLAUNCH (after landing)

POSTLAUNCH

• Hardware: All peripherals OFF
• Purpose: Landed, safe state

Emergency Override

From any state, you can return to PRELAUNCH using:

OSC_ANY_TO_PRELAUNCH

Communication Interfaces

SPI (Serial Peripheral Interface)

• SPI2: LPS22HH sensors (Mario and Luigi)
• SPI6: LSM6DSO sensor (Binoo)

I2C

• I2C2: MS5611 (Bowser) and LSM6DSO (Toopy)

UART

• USART6: Debug output (configured in Driver::uart6)

Getting Started

System Initialization

The system boots through main_system.cpp:

void run_main() {
    // 1. Initialize all tasks
    CubeTask::Inst().InitTask();
    DebugTask::Inst().InitTask();
    FlightTask::Inst().InitTask();
    IMUTask::Inst().InitTask();
    BaroTask::Inst().InitTask();

    // 2. Print boot info
    SOAR_PRINT("\n-- SOAR SYSTEM --\n");

    // 3. Test sensors (example)
    Command testIMU(REQUEST_COMMAND, IMU_REQUEST_LIN_ACC);
    IMUTask::Inst().GetEventQueue()->Send(testIMU);

    // 4. Start FreeRTOS scheduler
    osKernelStart();
}

Task Configuration

Task priorities and stack sizes are defined in SystemDefines.hpp:

// All tasks currently have priority 2
constexpr uint8_t FLIGHT_TASK_RTOS_PRIORITY = 2;
constexpr uint8_t IMU_TASK_RTOS_PRIORITY = 2;
constexpr uint8_t BARO_TASK_RTOS_PRIORITY = 2;

// Stack sizes (in words)
constexpr uint16_t FLIGHT_TASK_STACK_DEPTH_WORDS = 512;
constexpr uint16_t IMU_TASK_STACK_DEPTH_WORDS = 512;
constexpr uint16_t BARO_TASK_STACK_DEPTH_WORDS = 512;

Example Usage

Requesting IMU Data

// Create a command to request linear acceleration
Command cmd(REQUEST_COMMAND, IMU_REQUEST_LIN_ACC);

// Send to IMU task
IMUTask::Inst().GetEventQueue()->Send(cmd);

// IMUTask will respond by sending IMUData to FlightTask

Controlling Hardware

// Open solenoid valve 1
Command cmd(CONTROL_ACTION, OSC_OPEN_SOL1);
FlightTask::Inst().GetEventQueue()->Send(cmd);

// Close solenoid valve 1
Command cmd2(CONTROL_ACTION, OSC_CLOSE_SOL1);
FlightTask::Inst().GetEventQueue()->Send(cmd2);

Reading Barometer Data

// Request new barometer sample
Command cmd(REQUEST_COMMAND, BARO_REQUEST_NEW_SAMPLE);
BaroTask::Inst().GetEventQueue()->Send(cmd);

// Request debug output of barometer values
Command cmd2(REQUEST_COMMAND, BARO_REQUEST_DEBUG);
BaroTask::Inst().GetEventQueue()->Send(cmd2);

Key Design Patterns

1. Singleton Pattern

Each task uses Task::Inst() to access a single instance:

FlightTask::Inst().GetEventQueue()->Send(command);

2. Command Pattern

All inter-task communication uses Command objects with specific command types

3. State Pattern

Flight logic organized into distinct states with entry/exit handlers

4. Hardware Abstraction

GPIO operations wrapped in namespace functions:

GPIO::LED_GREEN::On();
GPIO::SOL1::Off();