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--- pm:prj2026:alexandru.predescu:patricia.bratu [2026/05/15 17:55]
patricia.bratu [Components]
+++ pm:prj2026:alexandru.predescu:patricia.bratu [2026/05/26 15:19] (current)
patricia.bratu [Video Demo & Explanations]
@@ Line 14: / Line 14: @@
 ===== Hardware Design =====
-==== Components ====
+==== 1.Components ====
 ^ Component ^ Type / Model ^ Role  ^
@@ Line 25: / Line 25: @@
 | Power Supply | 5V / 2A (External) | Provides the necessary current for the motors and the pump. |
 | Connectivity | Breadboard & Jumpers | Used for making electrical connections between modules. |
-{{:pm:prj2026:alexandru.predescu:screenshot_2026-05-15_at_17.54.22.png?900|}}
+==== 2.Electrical Schematic ====
+{{:pm:prj2026:alexandru.predescu:screenshot_2026-05-15_at_17.54.22.png?850|}}
+**Design Explanations:**
+  * **Power Isolation:** The water pump is powered directly from the 12V rail via the relay. This prevents the high current draw and electrical noise of the motor from affecting the ATmega328P stability.
+  * **Voltage Regulation:** The LM2596 Buck Converter is tuned to exactly 5.0V. It powers the MCU and the servos, which require more current than a standard PC USB port can provide.
+  * **Safety Features:** A flyback diode (D1) is placed at the input to prevent damage from reverse polarity. The relay provides galvanic isolation between the water pump circuit and the microcontroller.
+==== 3. Pin Configuration and Rationale ====
+To ensure efficient operation and hardware-level precision, the following pins were selected:
+  * **PD2 (INT0):** Connected to the **Digital Output (DO)** of the Flame Sensor.
+    * //Rationale:// PD2 supports External Interrupts. This allows the system to react instantly to a fire detection without waiting for the main code loop to finish other tasks.
+  * **PB1 (OC1A) & PB2 (OC1B):** Connected to the **PWM** pins of Servo 1 and Servo 2.
+    * //Rationale:// These pins are linked to **Timer 1 (16-bit)**. Since we are not using Arduino libraries, Timer 1 provides the high resolution necessary for smooth 50Hz servo pulses (20ms period).
+  * **PD4:** Connected to the **Relay Input (IN)**.
+    * //Rationale:// A standard GPIO used to toggle the pump. It is kept on Port D to group it with other digital control signals.
+  * **VCC (5V) & GND:** All logic components (MCU, Sensor, Servos) share the 5V rail from the Buck Converter to ensure common ground reference for signals.
+==== 4. Hardware Implementation and Testing ====
+==== Physical Assembly ====
+{{:pm:prj2026:alexandru.predescu:whatsapp_image_2026-05-15_at_18.29.54.jpeg?500|}}
+{{:pm:prj2026:alexandru.predescu:whatsapp_image_2026-05-15_at_18.29.54_1_.jpeg?500|}}
+//The images above show the final wiring on the breadboard, with the Buck Converter supplying power to the flame sensor and the Xplained Mini board.//
+==== Proof of Functionality: Flame Detection ====
+To verify the system, the Flame Sensor and the integrated LED (PB5) were tested.
+  * **Test Procedure:** A flame was introduced near the sensor.
+  * **Result:** The sensor's onboard LED triggered, and the ATmega328P successfully pulled the PD2 pin low, subsequently powering up the PB5 BUZZER on the Xplained Mini board.
+  * **Conclusion:** The interrupt logic is functional, and the sensor is correctly calibrated via its onboard potentiometer.
+====Image with the process====
+{{:pm:prj2026:alexandru.predescu:whatsapp_image_2026-05-16_at_15.45.34.jpeg?500|}}
+===== 3. Software Implementation & Project Details =====
+==== Current Status of the Software Implementation ====
+The software implementation is fully functional and stable. The application is written in **pure C** for the ATmega328P microcontroller using PlatformIO. It successfully runs a real-time fire detection and suppression loop. The system concurrently monitors a flame sensor via both digital and analog channels, triggers an instantaneous acoustic alarm via hardware interrupts, controls a high-power water pump through an isolated relay module, and drives a 2-axis sweep mechanism using hardware PWM.
+{{:pm:prj2026:alexandru.predescu:whatsapp_image_2026-05-23_at_13.13.33.jpeg?200|}}
+==== Motivation for Library Selection ====
+In order to maximize execution speed, minimize memory footprint, and strictly adhere to low-level academic requirements, **no external third-party libraries (such as Arduino.h or Servo.h) were used**.
+  * **[[https://www.nongnu.org/avr-libc/user-manual/modules.html|avr/io.h]]:** Selected to provide direct access to the register maps of the ATmega328P (e.g., DDRD, PORTB, ADMUX), ensuring zero-overhead bit manipulation.
+  * **avr/interrupt.h:** Chosen to handle the hardware vector management (`ISR(INT0_vect)`) required for sub-microsecond event handling.
+  * **util/delay.h:** Used exclusively for minor debouncing and regulating the sweep velocity of the servo motor where strict asynchronous non-blocking timers were not vital.
+==== Element of Novelty ====
+The primary novelty of this project lies in its **Hybrid Dual-Channel Sensor Architecture**. Instead of relying on a single data path, the flame sensor is evaluated simultaneously through two distinct subsystems:
+. A **Digital Safety Path** linked directly to a high-priority hardware interrupt line.
+. An **Analog Measurement Path** processed via the ADC.
+This creates a fail-safe paradigm: the acoustic alarm bypasses any software delay or loop blockage to guarantee immediate warning, while the analog loop calculates the spatial presence of the threat to dynamically orchestrate physical suppression.
+==== Justification of PM Laboratory Functionalities ====
+The architecture incorporates core concepts from three foundational PM laboratories:
+  * **Laboratory 1 & 2 (Digital I/O):** Used to actuate the isolated relay module on pin **PD4** (utilizing an active-low sinking configuration suitable for the lab's relay board) and driving the visual status LED on **PB5**.
+  * **Laboratory 3 (External Interrupts):** Implemented via **INT0** on pin **PD2**. It processes the digital output (DO) of the flame sensor on a falling edge to instantly trigger the emergency buzzer on **PD3**, guaranteeing deterministic real-time response.
+  * **Laboratory 6 & 7 (Analog-to-Digital Converter - ADC):** Implemented on channel **ADC0 (PC0)** using an AVCC reference and a prescaler of 128. It quantifies the light intensity in the infrared spectrum to distinguish between ambient environmental lighting and an active flame threat.
+  * **Laboratory 5 (Timers & PWM):** Utilizes **Timer 1 (16-bit)** configured in **Fast PWM Mode (Mode 14)** with `ICR1` acting as TOP to generate a precise **50 Hz** frequency (20ms period). This hardware-driven signal operates on pin **PB1 (OC1A)** to seamlessly position the servo motor.
+==== Project Skeleton & Functional Interaction ====
+The software layout is divided into explicit hardware initialization blocks and a single, low-latency execution loop:
+<code>
++-----------------------------------------------------------------------+
+|                         Hardware Initialization                       |
+|          (ADC_init()  |  PWM_init()  |  INT0_init()  |  sei())        |
++-----------------------------------------------------------------------+
+                                    |
+                                    v
++-----------------------------------------------------------------------+
+|                           Main Loop [while(1)]                        |
++-----------------------------------------------------------------------+
+| 1. Sample raw IR intensity from PC0 (ADC0).                           |
+| 2. Evaluate threshold criteria (valoare_foc < 400).                   |
++-----------------------------------------------------------------------+
+          |                                            |
+ [Fire Detected: FALSE]                        [Fire Detected: TRUE]
+          |                                            |
+          v                                            v
++------------------------------------+      +------------------------------------+
+| - Pull PD4 LOW (Activate Relay)    |      | - Pull PD4 HIGH (Deactivate Relay) |
+| - Pull PD3 HIGH (Maintain Buzzer)  |      | - Pull PD3 LOW (Silence Buzzer)    |
+| - Increment Servo position         |      | - Snap Servo back to Bisectore     |
+|   (Sweep 0° to 120° dynamically)   |      |   (60° Rest Position)              |
++------------------------------------+      +------------------------------------+
+          |                                            |
+          +---------------------> [_delay_ms(20)] <----+
+                                    |
+                                    v
+                             (Repeat Loop)
+</code>
+=== Asynchronous Interruption Event ===
+Independent of the flow chart above, if pin **PD2** drops to 0V at any microsecond, the CPU stops execution instantly:
+<code>
+ISR(INT0_vect) {
+    stare_alerta = 1;
+    PORTD |= (1 << PD3); // FORCES BUZZER ON IMMEDIATELY
+}
+</code>
+=== Validation ===
+System verification was carried out systematically:
+  * **Logic Validation:** Probed with an oscilloscope/multimeter on pin `PD4` to verify that state toggles matched the active-low transistor network of the relay module.
+  * **Timing Validation:** Verified via the built-in logic analyzer that the Timer 1 configuration outputs an exact pulse width between $1\,\text{ms}$ (`OCR1A = 2000`) and $1.66\,\text{ms}$ (`OCR1A = 3333`), ensuring safe physical operation within bounds.
+==== Sensor Calibration ====
+The infrared phototransistor module required hardware-software co-calibration to avoid false positives caused by laboratory overhead fluorescent lighting:
+  * **Hardware Sizing:** The onboard LM393 potentiometer was trimmed under normal ambient conditions until the onboard status LED turned off, isolating the digital output (**DO**) to trigger only when exposed to highly dense IR spectrums (e.g., a lighter flame within 30cm).
+  * **Software Mapping:** Through iterative trial testing, an empirical ADC threshold of **400** units was established. Ambient room light sits safely at $700 - 900$ units ($3.5\text{V} - 4.5\text{V}$), whereas an active flame drops the analog readout sharply under $300$ units ($1.5\text{V}$), providing a robust noise-margin buffer.
+==== Optimizations ====
+  * **Why & Where:** To completely avoid standard CPU processing delays when driving mechanical parts, the servo sweep was optimized via **Hardware-driven PWM**. Instead of bit-banging pins or calling blocking delays, modifying the `OCR1A` register lets the internal timer handle the waveform generation autonomously.
+  * **Memory Optimization:** Global variables are minimized, and critical state indicators (such as `stare_alerta`) are decorated with the `volatile` qualifier. This prevents the compiler from erroneously optimizing the variable into a CPU register, ensuring accurate cross-boundary access between the background ISR and the foreground main loop.
+==== Video Demo & Explanations ====
+> Directly access the official project demonstration video hosted on the university's cloud platform here:
+> [[ https://ctipub-my.sharepoint.com/:v:/g/personal/patricia_bratu_stud_acs_upb_ro/IQD1YnXKKr1bT7-sRjXw5bfBAZzRhBom3UHN_MiHRUU0xuM?nav=eyJyZWZlcnJhbEluZm8iOnsicmVmZXJyYWxBcHAiOiJPbmVEcml2ZUZvckJ1c2luZXNzIiwicmVmZXJyYWxBcHBQbGF0Zm9ybSI6IldlYiIsInJlZmVycmFsTW9kZSI6InZpZXciLCJyZWZlcnJhbFZpZXciOiJNeUZpbGVzTGlua0NvcHkifX0&e=bmzSTt | 🎬 Click Here to Watch: Fire Suppression System Demo ]]
+  * **VIDEO:** Demonstrates system startup. The servo automatically aligns itself to the central **$60^\circ$ bisector** point, remaining at idle. The buzzer and water pump are silent.
+Link to the project repository https://github.com/PatriciaBratu/Fire-Detection-and-Suppression-System.git