Project/andrei.rusanescu (#1005)

* Added index.md file.

Signed-off-by: Andrei Rusanescu <andreirusanescu154@gmail.com>

* Added documentation

Signed-off-by: Andrei Rusanescu <andreirusanescu154@gmail.com>

* Added architectural diagram

Signed-off-by: Andrei Rusanescu <andreirusanescu154@gmail.com>

* Fixed: removed embedded base64 images from SVG

* Updated log and added schematic.

Signed-off-by: Andrei Rusanescu <andreirusanescu154@gmail.com>

* Compressed schematic

Signed-off-by: Andrei Rusanescu <andreirusanescu154@gmail.com>

* Added hardware images

Signed-off-by: Andrei Rusanescu <andreirusanescu154@gmail.com>

---------

Signed-off-by: Andrei Rusanescu <andreirusanescu154@gmail.com>

Author: andreirusanescu

website/versioned_docs/version-acs_cc/project/2026/andrei.rusanescu/IMG_3536.webp

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+# CargoBot
+Remote-controlled cargo robot with Bluetooth telemetry
+
+:::info
+
+**Author**: Andrei Rusanescu \
+**GitHub Project Link**: [link_to_github](https://github.com/UPB-PMRust-Students/acs-project-2026-andreirusanescu)
+
+:::
+
+<!-- do not delete the \ after your name -->
+
+## Description
+
+CargoBot is a remote-controlled four-wheeled robot that carries cargo and navigates surfaces with imperfections. It is controlled from a laptop keyboard via Bluetooth and uses an STM32 Nucleo-U545RE-Q microcontroller programmed in Rust with Embassy-rs. It sends real-time telemetry data to a PC dashboard via Bluetooth, while simultaneously displaying information on an onboard OLED.
+
+The central idea of the project is measuring and visualizing the impact of cargo load on motor performance: when the robot carries something heavy, the PID controller automatically increases the PWM duty cycle to maintain a constant speed. This compensation is observable live on the robot's OLED, on the PC dashboard, and through 3 LEDs (green/yellow/red) that visually indicate the effort level.
+
+## Motivation
+
+I am particularly interested in cars and networking. This project combines multiple peripherals studied in the lab (PWM, GPIO, I2C, UART, Bluetooth) into a functional system. It is a challenge that clearly demonstrates technical effort - the difference in motor effort with and without cargo, and how to compensate for the load.
+
+## Architecture
+
+![Architecture](schema_bloc.svg)
+
+The system is organized around five main subsystems:
+
+**1. MCU (STM32 Nucleo-U545RE-Q)**
+The central unit running all Embassy-rs async tasks. Coordinates all subsystems and shared state protected by Mutex.
+
+**2. Motor Subsystem**
+The L298N dual H-bridge receives PWM signals from the STM32 and drives 4 DC motors (2 per channel, left/right side in parallel - skid steering). The two IR LM393 optical sensors read encoder disc pulses on GPIO interrupts and compute RPM per side.
+
+**3. Sensing Subsystem**
+- MPU-6500 (I2C, address 0x68): reads accelerometer + gyroscope data, combined via complementary filter to get a stable tilt angle
+- 2x HC-SR04 (GPIO trigger/echo): front and rear obstacle detection
+- 2x IR LM393 encoders: RPM feedback for PID
+
+**4. Communication Subsystem**
+HC-06 Bluetooth module connected to STM32 via UART. Bidirectional: laptop sends movement commands (forward/backward/left/right + speed), robot sends back JSON telemetry at 5Hz.
+
+**5. Display & Indicators Subsystem**
+- OLED SSD1306 128x64 (I2C, address 0x3C, shared bus with IMU): displays RPM, tilt angle, obstacle distance, state, load level
+- 3x LEDs (green/yellow/red) on GPIO: visual indicator of motor effort based on PWM duty cycle
+- Passive buzzer on PWM: horn and audio feedback
+
+**Embassy-rs Async Tasks:**
+
+| Task | Frequency | Responsibility |
+|------|-----------|----------------|
+| sensor_task | 20 Hz | Read IMU (I2C) + ultrasonic sensors |
+| motor_task | 50 Hz | Apply PWM to L298N, read encoders |
+| navigation_task | 10 Hz | State machine: FORWARD / COMPENSATE / AVOID / STOP |
+| telemetry_task | 5 Hz | Serialize JSON and send over UART to HC-06 |
+| display_task | 4 Hz | Update OLED |
+
+**Navigation State Machine:**
+
+| State | Entry Condition | Action |
+|-------|----------------|--------|
+| FORWARD | No obstacle | Move at target speed, PID active |
+| COMPENSATE | Pitch > 5 deg (ramp) | Increase PWM proportional to tilt angle |
+| AVOID | Obstacle < 30cm | Stop, rotate, resume forward |
+| STOP | Manual command / error | Motors off, telemetry continues |
+
+**Peripheral Usage:**
+
+| Peripheral | Component | Usage |
+|-----------|-----------|-------|
+| PWM | STM32 -> L298N | Motor speed control (0–100% duty cycle) |
+| PWM | STM32 -> Buzzer | Horn |
+| GPIO Output | STM32 -> HC-SR04 trigger | 10 micro-s pulse to trigger ultrasonic |
+| GPIO Input Interrupt | HC-SR04 echo -> STM32 | Measure echo duration -> distance |
+| GPIO Input Interrupt | LM393 encoders -> STM32 | Count pulses -> compute RPM |
+| GPIO Output | STM32 -> LEDs R/Y/G | Load indicator: green (&lt;35%), yellow (35–65%), red (>65%) |
+| GPIO Output | STM32 -> L298N IN1-IN4 | Motor direction control |
+| I2C (shared bus) | STM32 -> MPU-6500 (0x68) | Accelerometer + gyroscope for tilt angle |
+| I2C (shared bus) | STM32 -> SSD1306 (0x3C) | OLED telemetry display |
+| UART | STM32 -> HC-06 | Bidirectional Bluetooth: commands in, telemetry out |
+
+## Log
+
+<!-- write your progress here every week -->
+
+### Week 6 - 12 Apr
+Ordered most of the components needed.
+
+### Week 13 - 19 Apr
+Assembled the mechanical parts (wheels, motors, car platform).
+
+### Week 20 - 26 Apr
+Working on the Schematic in KiCad.
+Tested individual components: bluetooth module, display, motors, distance sensors, LM393 speed sensors.
+
+### Week 27 Apr - 3 May
+Ordered Li-Ion Samsung 18650 3.6V 3450mAh 8A batteries, a charger for the batteries,
+more male-female and female-female jumpers and a smaller breadboard (400 points).
+
+### Week 4 - 10 May
+Soldered IMU and OLED display in the lab.
+Assembled final product.
+Started to write the software for the cargobot and tested it carrying another car.
+The HC-SR04 sensors are not so precise as the car sometimes crashes into walls if driven into.
+
+### Week 11 - 17 May
+
+
+## Hardware
+
+The robot is built on a 4WD chassis with 4 DC motors (3–6V) driven through an L298N dual H-bridge using skid steering (left/right side in parallel). Speed and direction are controlled via PWM from the STM32. Two IR optical sensors read encoder discs on the motors to compute RPM. An MPU-6500 IMU over I2C measures tilt angle using a complementary filter. Two HC-SR04 ultrasonic sensors handle obstacle detection front and rear. An SSD1306 OLED displays live telemetry. An HC-06 Bluetooth module provides bidirectional communication with the laptop.
+
+![Car from above](IMG_3541.webp)
+![Car from a side](IMG_3536.webp)
+
+### Schematics
+
+<!-- Place your KiCAD schematics here in SVG format. -->
+KiCad Schematic:
+![KiCad Schematic](PM_PROJECT.svg)
+
+
+
+### Bill of Materials
+
+| Device | Usage | Price |
+|--------|--------|-------|
+| [STM32 Nucleo-U545RE-Q](https://www.st.com/en/evaluation-tools/nucleo-u545re-q.html) | Main microcontroller (Cortex-M33), runs all Embassy-rs tasks | 0 RON (provided by university) |
+| [4x DC motors (3-6V), encoder discs, wheels](https://www.bitmi.ro/set-motor-dc-3v-6v-cu-reductor-si-roata-11227.html) | Wheels and motors for the CargoBot | [40 RON](https://www.bitmi.ro/set-motor-dc-3v-6v-cu-reductor-si-roata-11227.html)
+| [2x IR Speed Sensor LM393](https://sigmanortec.ro/Senzor-viteza-IR-LM393-p125686023) x2 | Optical encoder reading, counts pulses from encoder discs to compute RPM | [16.22 RON](https://sigmanortec.ro/Senzor-viteza-IR-LM393-p125686023) |
+| [L298N Dual H-Bridge](https://sigmanortec.ro/Punte-H-Dubla-L298N-p125423236) | Motor driver, controls speed (PWM) and direction of both motor sides | [8.96 RON](https://sigmanortec.ro/Punte-H-Dubla-L298N-p125423236) |
+| [MPU-6500 Accelerometer & Gyroscope](https://sigmanortec.ro/Modul-Accelerometru-Giroscop-I2C-MPU-6500-6-axe-p136248782) | 6-axis IMU, measures tilt angle via complementary filter (I2C, 0x68) | [9.92 RON](https://sigmanortec.ro/Modul-Accelerometru-Giroscop-I2C-MPU-6500-6-axe-p136248782) |
+| [HC-06 Bluetooth Module](https://sigmanortec.ro/Modul-bluetooth-HC-06-p125923853) | Bidirectional wireless UART, receives keyboard commands, sends telemetry JSON | [25.13 RON](https://sigmanortec.ro/Modul-bluetooth-HC-06-p125923853) |
+| [OLED SSD1306 0.96" I2C](https://sigmanortec.ro/display-oled-096-i2c-iic-alb) | On-board display, shows RPM, tilt, obstacle distance, state, load level (I2C, 0x3C) | [14.01 RON](https://sigmanortec.ro/display-oled-096-i2c-iic-alb) |
+| [2x HC-SR04 Ultrasonic Sensor](https://sigmanortec.ro/Senzor-ultrasunete-HC-SR04-p125423514) x2 | Obstacle detection, front and rear, GPIO trigger/echo | [18.80 RON](https://sigmanortec.ro/Senzor-ultrasunete-HC-SR04-p125423514) |
+| [18650 Battery Holder 2S](https://sigmanortec.ro/suport-acumulatori-18650-2s) | Holds 2x 18650 cells in series, 7.4V output for L298N and STM32 | [5.74 RON](https://sigmanortec.ro/suport-acumulatori-18650-2s) |
+| [2x Li-Ion Samsung 18650 3.6V 3450mAh 8A](https://www.emag.ro/acumulator-li-ion-samsung-18650-3-6v-3450mah-8a-cu-borne-joase-si-fara-bms-model-inr18650-35e-3450ma-lincr18650-35e/pd/DWVV74MBM/) | Batteries to provide voltage for the motors and for the board | [63 RON](https://www.emag.ro/acumulator-li-ion-samsung-18650-3-6v-3450mah-8a-cu-borne-joase-si-fara-bms-model-inr18650-35e-3450ma-lincr18650-35e/pd/DWVV74MBM/) |
+| [Battery charger](https://www.emag.ro/incarcator-dublu-pentru-acumulator-baterie-reincarcabila-4-2v-1000ma-li-ion-ultrafire-18650-10440-14500-16340-17335-17500-17670-18500-0201/pd/DMG7FVBBM/) | Charges the Li-ion batteries | [35 RON](https://www.emag.ro/incarcator-dublu-pentru-acumulator-baterie-reincarcabila-4-2v-1000ma-li-ion-ultrafire-18650-10440-14500-16340-17335-17500-17670-18500-0201/pd/DMG7FVBBM/) |
+| 3x LED (red/yellow/green) + resistors | Visual motor effort indicator | 0 RON (owned) |
+| [Female-Female jumper wires](https://sigmanortec.ro/40-fire-Dupont-10cm-Mama-Mama-p129872525) | Wires for connections | [7.73 RON](https://sigmanortec.ro/40-fire-Dupont-10cm-Mama-Mama-p129872525) |
+| [Male-Female jumper wires](https://sigmanortec.ro/40-fire-Dupont-10cm-Tata-Mama-p210855157) | Wires for connections | [7.73 RON](https://sigmanortec.ro/40-fire-Dupont-10cm-Tata-Mama-p210855157) |
+| Male-Male jumper wires | Wires for connections | 0 RON (owned) |
+
+## Software
+
+| Library | Description | Usage |
+|---------|-------------|-------|
+| [embassy-stm32](https://github.com/embassy-rs/embassy) | Async HAL for STM32U5 | PWM, I2C, UART, GPIO, Timer drivers |
+| [embassy-executor](https://github.com/embassy-rs/embassy) | Async task executor | Spawning and running concurrent tasks |
+| [embassy-time](https://github.com/embassy-rs/embassy) | Async timers and delays | Task scheduling at fixed frequencies |
+| [embassy-sync](https://github.com/embassy-rs/embassy) | Synchronization primitives | Mutex and Channel for inter-task shared state |
+| [ssd1306](https://github.com/rust-embedded-community/ssd1306) | OLED SSD1306 driver | I2C display rendering |
+| [embedded-graphics](https://github.com/embedded-graphics/embedded-graphics) | 2D graphics library | Drawing text and shapes on OLED |
+| [heapless](https://github.com/rust-embedded/heapless) | No-alloc data structures | String/Vec without heap allocation |
+| [defmt](https://github.com/knurling-rs/defmt) + defmt-rtt | Logging framework | Debug output via probe |
+| [libm](https://github.com/rust-lang/libm) | Math functions (no_std) | atan2, sqrt for complementary filter |
+| Python pyserial | Serial communication | PC-side script to receive telemetry and send commands over Bluetooth |
+| Python matplotlib / Flask | Data visualization | Live dashboard with RPM, PWM, tilt, distance graphs |
+
+## Links
+
+1. [Embassy-rs documentation](https://embassy.dev)
+2. [STM32 Nucleo-U545RE-Q user manual](https://www.st.com/en/evaluation-tools/nucleo-u545re-q.html)
+3. [MPU-6500 datasheet](https://invensense.tdk.com/products/motion-tracking/6-axis/mpu-6500/)
+4. [SSD1306 OLED driver crate](https://github.com/rust-embedded-community/ssd1306)
+5. [L298N datasheet](https://www.st.com/resource/en/datasheet/l298.pdf)
+6. [HC-SR04 ultrasonic sensor guide](https://cdn.sparkfun.com/datasheets/Sensors/Proximity/HCSR04.pdf)