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--- pm:prj2026:jan.vaduva:gabriel.eftimie [2026/05/18 17:57]
gabriel.eftimie [Jurnal]
+++ pm:prj2026:jan.vaduva:gabriel.eftimie [2026/05/25 00:09] (current)
gabriel.eftimie [Software Design]
@@ Line 158: / Line 158: @@
 | Positive (+) | 4 PIN PWM Pin 4 | High-power +12V Supply for the Fan |
 | Negative (-) | System GND Rail | Common ground loop safety connection |
-===== Software Design =====
+===== Firmware Description & Software Architecture =====
+==== 1. Development Environment (IDE & Frameworks) ====
+The project utilizes a hybrid software architecture tailored to the specific capabilities of each microcontroller. The entire system is managed via **Visual Studio Code (VS Code)** combined with the **PlatformIO** extension. This IDE was chosen over the standard Arduino IDE due to its superior toolchain management and the ability to handle independent compilations for different architectures (ESP32 and AVR) within the same environment.
-<note tip>
+  * **Central Node (Controller - ESP32-S3 T-HMI):** The firmware is developed using the official **ESP-IDF (Espressif IoT Development Framework)** in C. ESP-IDF was selected to ensure low-level control over hardware peripherals (such as hardware timers for PWM and the I80 parallel interface for the display) and to run the application on top of a Real-Time Operating System (**FreeRTOS**).
-Descrierea codului aplicaţiei (firmware):
+  * **Remote Node (Control Unit - Arduino Mega 2560):** The firmware utilizes the standard **Arduino framework (C++)**, which significantly simplifies the management of hardware serial communication (''Serial1'' for the ESP-01S module) and the debouncing logic for the physical input buttons.
-  * mediu de dezvoltare (if any) (e.g. AVR Studio, CodeVisionAVR)
-  * librării şi surse 3rd-party (e.g. Procyon AVRlib)
-  * algoritmi şi structuri pe care plănuiţi să le implementaţi
-  * (etapa 3) surse şi funcţii implementate
-</note>
+==== 2. 3rd-Party Libraries and Sources ====
+The system is designed with minimal reliance on external third-party libraries, implementing critical logic from scratch to maximize efficiency and stability. For the Central Node, native ESP-IDF components were exclusively used:
+  * ''driver/ledc.h'': For generating the hardware PWM signals required by the fan.
+  * ''driver/gpio.h'' & ''esp_timer.h'': For managing hardware interrupts (ISR) and high-precision microsecond timing.
+  * ''esp_lcd_panel_*.h'': Native drivers for initializing and pushing data to the ST7789 LCD via the I80 parallel bus.
+  * //Note:// No external libraries (such as Adafruit DHT) were used for the AM2302/DHT22 temperature sensor. The 1-Wire communication protocol was manually implemented (bit-banging).
+==== 3. Planned & Implemented Algorithms and Structures ====
+The software architecture relies on the following core algorithms:
+  * **Digital Decoding Algorithm (Bit-Banging) for DHT22:** Because the ESP32-S3 FreeRTOS scheduler can cause microsecond desynchronization on the 1-Wire bus, a strict timing algorithm (''dht_wait_state'') was implemented. It measures high/low pulse durations in microseconds. Pulses longer than 40µs are interpreted as a logical ''1'', successfully reconstructing the 40-bit data packet (16-bit humidity, 16-bit temperature, 8-bit checksum).
+  * **Tachometric (RPM) Calculation Algorithm:** Utilizes an Interrupt Service Routine (ISR) attached to the falling edge of the fan's TACHO pin. A variable counts the pulses generated by the fan's internal Hall-effect sensor. Periodically, the interrupt is paused, and the pulse count is multiplied by a timing constant (e.g., 15, for a 2-second sampling interval) to calculate the exact Revolutions Per Minute (RPM).
+  * **Thermal Control Structure (Fan Curve):** A step-based linear conditional block maps the read temperature ranges to an 8-bit Duty Cycle interval (0–255). Predefined thresholds dynamically adjust the RPM (e.g., <25°C equals ~20% power; >35°C equals 100% power) to maintain an optimal cooling-to-noise ratio.
+  * **Framebuffer Rasterization for Display:** To prevent visual flickering on the LCD, characters are not drawn directly to the screen. Instead, they are drawn into an allocated memory structure (''uint16_t framebuffer[320 * 240]''). A rasterization algorithm parses a custom 8x8 font dictionary, applies a 3x scaling multiplier, maps the 16-bit RGB565 colors, and pushes the entire buffer to the display in a single block.
+==== 4. Implemented Sources and Functions (Stage 3 - Controller Node) ====
+The following critical C functions were developed and validated for the central unit:
+  * **''dht_wait_state(int state, int timeout_us)''**: A blocking function equipped with an internal timeout (based on ''esp_timer_get_time()'') that measures the duration of a logical state on the GPIO pin, preventing infinite loops in case of sensor disconnection.
+  * **''read_dht22(float *temp)''**: Initiates the sensor wake-up sequence, temporarily disables global OS interrupts (''taskDISABLE_INTERRUPTS'') to guarantee precise bus timing, decodes the bitstream, and validates data integrity via the checksum.
+  * **''tacho_isr_handler()''**: The hardware interrupt function. It incorporates a software debouncing mechanism (''now - last_pulse_time > 2500 µs'') to filter out parasitic electrical noise on the tachometer line before incrementing the ''pulse_count''.
+  * **''fan_hardware_init()''**: Configures the LEDC timer for a 25kHz frequency (the industry standard for 4-pin PC fans), sets the 8-bit resolution, and attaches the ISR to the RPM reading pin.
+  * **''init_display_primitive()''**: Initializes the 8-bit I80 parallel bus and configures the internal ST7789 display controller (including color inversion and XY memory mapping).
+  * **''draw_char_to_fb()'' / ''draw_string_to_fb()'' / ''clear_framebuffer()''**: A suite of custom graphical functions that take a string, read the corresponding binary pattern from the font matrix (''font8x8''), scale it, and write the pixel data into the framebuffer array.
+  * **''control_task()''**: The main FreeRTOS task running in an infinite loop (''while(1)''). It orchestrates the overall system logic: reads the DHT22 sensor, calculates the RPM while safely pausing interrupts, applies the thermal curve via ''ledc_set_duty'', renders the UI to the framebuffer, flushes it to the screen, and suspends itself for 2 seconds (''vTaskDelay'').
 ===== Results / Photos =====
@@ Line 175: / Line 196: @@
 Remote Control:
 {{ :pm:prj2026:jan.vaduva:pozatelecomandaventilator.jpeg?direct&400 |}}
+Testing that shows RPM and the temperature sensor working properly:
+{{ :pm:prj2026:jan.vaduva:testingtemperatureandrpm.jpeg?direct&400 |}}
 ===== Concluzii =====
@@ Line 181: / Line 204: @@
 <note warning>
 {{:pm:prj2026:jan.vaduva:schema_electrica_pm.fzz_1_.zip|}}
+{{:pm:prj2026:jan.vaduva:videotestareeftimiegabriel.zip|}}
 </note>