Shelter Environmental Monitoring and Control System

[daviddaguero]

High-level project description

The project aims to develop a real-time environmental monitoring and control system for a shelter, using the STM32 microcontroller and FreeRTOS for efficient task management. Integrating various sensors to monitor temperature, battery status, motion, and fire, the system ensures the safety and comfort of shelter occupants. Key features include automated gate control, fan-based temperature regulation, battery level indication, and data transmission to a remote monitoring center. With FreeRTOS, the STM32 manages concurrent tasks, handling sensor monitoring, real-time data processing, and responsive control actions like gate and fan operation. The use of Direct Memory Access (DMA) enhances efficiency by reducing CPU load, enabling reliable and responsive operation in a low-power, real-time environment.

Project Objectives

1. Real-Time Environmental Monitoring

Develop a system to monitor environmental factors like temperature, battery status, motion, and fire within the shelter, ensuring occupant safety and comfort.

2. Automated and Manual Gate Control

Implement automated gate control based on sensor inputs, with a manual override feature to allow user control in emergencies.

3. Temperature-Controlled Fan Activation

Use temperature data to regulate fan speed through PWM, ensuring effective cooling based on real-time conditions.

4. Battery Level Indication

Provide a clear indication of battery status using PWM to adjust LED brightness, showing low, medium, or full charge levels.

5. Data Transmission to Remote Monitoring Center

Transmit sensor data to an external monitoring center every 30 seconds, supporting on-demand data requests for remote oversight.

6. Display Interface

Display real-time temperature data on an external screen via I2C, enhancing user awareness of current shelter conditions.

7. Efficient Task Management with FreeRTOS

Utilize FreeRTOS to enable concurrent task management, prioritizing critical operations like fire and motion detection, ensuring timely responses.

8. DMA for Optimized Data Handling

Integrate DMA to offload data transfers between peripherals and memory, reducing CPU usage and enhancing power efficiency.

9. Scalability and Modularity

Design the system to allow easy integration of additional sensors or components, supporting future expansions and modifications.

10. Reliability and Low Power Consumption

Ensure reliable, continuous operation with minimal power consumption, particularly in battery-dependent environments.

Requirements

Functional Requirements

1. Environmental monitoring

• The system must monitor temperature, battery voltage, and sensor inputs (motion, fire detection) using the ADC.
• Motion and infrared sensors must detect threats and trigger appropriate actions

  Motion Detection:

• When the motion sensor detects a nearby threat, it sends a high signal to the system.
• The sensor must detect movement within a range of 3 meters.
• The detected object's speed should be between 0.5 to 1.5 meters per second (typical for a slow-moving human or "zombie").
• The system must only respond to human-sized objects, ignoring smaller objects to avoid false alarms.
• Upon detection, the system must close the door and trigger an alarm.

  Fire Detection:

  When the infrared sensor detects a fire inside the shelter (at a radiation level of 3 to 5 micrometers), the system must trigger an alarm and open the door.

  Temperature Monitoring:

  The temperature sensor must close the door if the temperature drops below 24 degrees Celsius.

  2. Manual Gate Control

• A manual override switch with two pins (OVERRIDE_BUTTON and PANIC_BUTTON) must allow user control over the gate via GPIO.
• The manual mode is activated when the OVERRIDE_BUTTON pin on the switch is set to 1, disabling automatic gate controls based on sensor detection (temperature, motion, or fire).
• When the PANIC_BUTTON pin on the switch is set to 1, the gate opens; when the PANIC_BUTTON pin is set to 0, the gate closes.

  3. Battery Level Indication

  The battery’s current charge level must be indicated using PWM (Pulse Width Modulation) to control the LED brightness

• Low battery level: Set the PWM duty cycle to 30%, producing a low LED brightness.
• Medium battery level: Set the PWM duty cycle to 60%, resulting in medium LED brightness.
• Full battery level: Set the PWM duty cycle to 100%, achieving maximum LED brightness.

  4. Actuator Control via PWM

  The system must control a fan using PWM based on temperature readings from the ADC:

• When the temperature is between 27 and 30 degrees Celsius, the PWM duty cycle should be set to 30% to run the fan at a low speed.
• When the temperature is between 30 and 35 degrees Celsius, the PWM duty cycle should increase to 60%, raising the fan speed.
• When the temperature exceeds 35 degrees Celsius, the PWM duty cycle should be set to 90% for maximum fan speed.
• If the temperature drops below 27 degrees Celsius, the PWM duty cycle should be 0% to turn off the fan.

  5. Data Transmission

• Sensor data (temperature, battery status, motion/fire detection) must be transmitted to a remote control center via UART at 30-second intervals.
• The system must support on-demand data transmission triggered by external commands.

  6. External Display Interface

• The system must interface with two external displays using I2C.
• The displays should show the current temperature reading from the temperature sensor in real time (one display for each temperature digit).

Non-Functional Requirements

1. Reliability

• The system must operate continuously and reliably, with real-time monitoring of environmental conditions.
• The gate control system must be highly responsive to both manual and automatic inputs in critical situations (e.g., high temperature, fire detection).

  2. Scalability

  The system must allow for additional sensors or actuators to be integrated without requiring significant architecture changes.

  3. Maintainability

  The system should be modular to simplify troubleshooting and future updates.

  4. Power Efficiency

  The system must minimize power consumption, particularly in battery-powered environments, by offloading tasks to DMA and reducing CPU usage.

  5. DMA Integration

• The system must use DMA to handle data transfers between peripherals (e.g., ADC, DAC, UART) and memory, minimizing CPU involvement.
• DMA must manage periodic data acquisition and actuator control, ensuring efficient operation and avoiding CPU bottlenecks.

Success Criteria for the Project

The project will be considered successful if the following criteria are met:

1. Reliable Environmental Monitoring:

The system accurately monitors temperature, battery status, motion, and fire conditions in real time, with no missed detections or false alarms under standard operating conditions.

2. Responsive Actuation:

Automated Gate Control: The gate responds promptly to sensor inputs, closing when motion is detected or when the temperature is below 24 degrees Celsius and opening in fire situations, with a response time within 1 second.

Manual Override: Manual control functions reliably when the override switch is activated, disabling automatic responses and allowing user control over the gate.

3. Accurately Battery Level Indication:

• The LED accurately reflects battery status with visible brightness changes corresponding to low, medium, and full charge levels
• PWM control ensures consistent LED brightness according to battery level in different ambient lighting conditions.

  4. Temperature-Based Fan Control:

  The fan speed adjusts correctly in response to temperature variations, with PWM duty cycle changes that match the specified thresholds.

  5. Data Transmission to Remote Center:

• Sensor data is transmitted to a remote monitoring center every 30 seconds with no data loss, maintaining reliable communication.
• On-demand data requests are processed without delay or errors.

  6. Display Readability:

  The external displays continuously show real-time temperature readings without interruption or lag, updating smoothly based on sensor inputs.

[sofiavalos]

System architecture

The proposed architecture based on the requirements is as follows:

[daviddaguero]

State machine diagram

stateDiagram-v2

    [*] --> MonitorEnvironment : Start Monitoring
    MonitorEnvironment --> MotionDetected : Motion Sensor Triggered
    %% MotionDetected --> Alarm : Nearby Threat Detected
    MotionDetected --> GateClosed : Close Gate

    MonitorEnvironment --> FireDetected : Fire Sensor Triggered
    %% FireDetected --> Alarm : Fire Detected Inside
    FireDetected --> GateOpened : Open Gate

    [*] --> ManualMode : Manual Override Activated
    ManualMode --> GateOpened : Panic button pressed
    ManualMode --> GateClosed : Panic button released

    MonitorEnvironment --> GateClosed : Temp < 24°C, Close Gate

    MonitorEnvironment --> FanOn : Temperature > 27°
    FanOn --> IncreaseFanSpeed : Temperature raises
    FanOn --> DecreaseFanSpeed : Temperature decreases
    FanOn --> FanOff : Temperature < 27°

    [*] --> BatteryCheck : Check Battery Level
    BatteryCheck --> LedSteadyOn : Battery level full
    BatteryCheck --> LedBlinkSlow : Battery level medium
    BatteryCheck --> LedBlinkFast : Battery level low

[sofiavalos]

Description of the main system modules

The main modules of our system are as follows:

• General configuration: Its main purpose is to configure all the sensors, GPIO I/O ports, and peripherals such as ADC, PWM, and timers.
• System response: This module is responsible for managing the system's responses, such as controlling the speed of the fan and the motor that drives the mechanism for the automatic door closure. Its function is to act immediately to mitigate unfavorable environmental conditions or prevent more severe consequences.
• Alarm and notification: The alarm and notification system includes the monitored battery level, which is indicated by varying the brightness of an LED, a fire alarm, and a display that allows the measured temperature to be checked. Its main function is to ensure the proper functioning of critical factors that help detect critical situations in the system.
• Remote center: This is the center where data is received via UART transmission, ensuring proper storage for later analysis of the measured conditions.
• Main: Manages the handlers and the connection between the other system modules.

In the system, the modules interact interdependently to ensure proper operation and efficient response to environmental conditions. The general configuration module is essential as it handles the initial setup of all sensors, GPIO I/O ports, and peripherals such as the ADC, PWM, and timers. Once these peripherals are configured, the system can collect environmental data (such as temperature, motion detection, fire presence, among others) and control devices (like motors or PWM signals) with precision. The ADC converts the analog signals from the sensors into digital values for processing, while the timers and PWM ensure precise control over output devices like the fan and door motor.

The system response module interacts closely with the configuration module as it uses sensor data to adjust parameters in real-time. For instance, when the temperature sensor detects a high temperature, the system responds by activating the fan or adjusting the motor speed to close the door, utilizing the pre-configured timers and PWM. This module must operate quickly to prevent severe consequences, and its interaction with the other modules ensures that the response is immediate and appropriate.

Meanwhile, the alarm and notification module plays a crucial role in continuous system monitoring. It consists of several functions that interact to provide an effective alert system in critical situations. The battery level monitors the energy status, while the fire alarm detects dangerous conditions. The display shows the real-time measured temperature, providing a clear view of the system’s status. This module integrates with the system response module, as the activation of alarms or notifications could trigger an immediate response, such as adjusting ventilation or closing the door.

The remote center is responsible for receiving, storing, and analyzing data from the system via UART transmission. This module ensures that the data is stored for later analysis, facilitating the evaluation of operational conditions and potential system improvements. The remote center relies on the interaction of all other modules, as it receives processed sensor data and system states for long-term analysis.

Finally, the main module manages communication between the modules and system controllers. It acts as an intermediary, coordinating the execution of tasks between different components and ensuring proper data and response management. This module also handles interruptions and handlers, allowing the system to respond efficiently to events like temperature changes or alarm triggers, while maintaining the data flow to the remote center and user interface.

Together, the interaction between these modules creates a dynamic system capable of autonomously responding to environmental conditions, maintaining continuous monitoring, and providing necessary alerts to ensure the system operates effectively and securely.

[daviddaguero]

Block Diagram

flowchart TD
    Main["Main"]
    GeneralConfiguration["General Configuration"]
    SystemResponse["System Response"]
    AlarmNotification["Alarm and Notification"]
    RemoteCenter["Remote Center"]

    Main --> GeneralConfiguration
    Main --> SystemResponse
    Main --> AlarmNotification
    Main --> RemoteCenter