# Multi-Functional Controller (MFC)
[](https://github.com/espressif/esp-idf)
[](https://www.espressif.com/en/products/socs/esp32-s3)
[](https://www.kicad.org/)
[](https://en.wikipedia.org/wiki/C_(programming_language))
[](https://www.freertos.org/)
[](#roadmap--milestones)
A custom, high-performance handheld remote controller engineered from scratch for dual-role applications: **long-range, low-latency RC vehicle control** and **USB/Bluetooth HID gaming**.
Built around the **ESP32-S3 (Xtensa® 32-bit LX7 dual-core @ 240 MHz)**, this project bridges hardware and software engineering—combining magnetic Hall-effect sensing, RF telemetry, hardware pulse-counted rotary inputs, hardware PWM audio synthesis, and an SPI graphics pipeline into a unified, battery-powered embedded platform.
---
## Prototype Showcase
Figure 1: Top assembly layout — Dual Hall-effect joysticks, rotary encoder, tactile buttons, 1.3" SPI OLED display, NeoPixel telemetry bar, and audio transducers.
Figure 2: Ergonomic profile — 2.4 GHz high-gain dipole antenna connected to the NRF24L01+ RF transceiver, rotary dial, and dual USB-C ports.
Figure 3: Underbody point-to-point bus routing — 6×9 cm perfboard with dedicated decoupled power rails (100 µF smoothing capacitor) and direct GPIO signal lines.
---
## Key Hardware & Architectural Features
- **Microcontroller Core:** Espressif ESP32-S3-N16R8 (16 MB Quad SPI Flash, 8 MB Octal PSRAM) running FreeRTOS preemptive multitasking.
- **Dual Wireless Pipelines:**
- **2.4 GHz RF (NRF24L01+):** Dedicated SPI radio module with external SMA antenna for low-latency, deterministic RC telemetry.
- **Bluetooth 5.0 LE & Wi-Fi:** Native wireless stacks for PC/gamepad HID modes and wireless telemetry streaming.
- **Precision Analog & Digital Controls:**
- **Dual Hall-Effect Joysticks:** Contactless magnetic sensing for zero stick drift and extended durability.
- **Hardware Pulse-Counted Rotary Encoder:** Quadrature decoding handled in hardware via the ESP32-S3 `pulse_cnt` peripheral to guarantee zero missed ticks during high-load processing loops.
- **Dedicated Navigation Buttons:** Tactile push-buttons configured with internal pull-ups for UI interaction and control toggling.
- **Multi-Sensor Audio & Visual Telemetry:**
- **1.3" SPI OLED Display (SH1106 / SSD1306):** Driven via hardware DMA SPI (`SPI2_HOST`) with custom frame buffering for menus, telemetry, and live status readouts.
- **Polyphonic Melodic Synthesis:** Passive buzzer modulated via hardware LEDC PWM timer (`LEDC_TIMER_0`, 13-bit duty resolution).
- **Percussive Acoustic Alerts:** Dual active buzzers for instant tactile/auditory feedback and warning signals.
- **Visual Beat & Metric Indicators:** Dedicated Kick (GPIO 21) and Hi-Hat (GPIO 22) LEDs alongside an 8-LED WS2812B NeoPixel RGB strip driven via RMT.
- **Power Subsystem:**
- Dual parallel 18650 Li-ion cells delivering **4800 mAh** combined capacity.
- Dual USB-C ports: one dedicated for high-efficiency battery charging and one for USB-UART flashing, debugging, and wired HID gamepad control.
- 100 µF low-ESR electrolytic capacitor buffering transient current spikes from RF transmission bursts and buzzer pulses.
---
## GPIO Pinout & Peripheral Mapping
The firmware (`firmware/main/mmcontroller.c`) allocates hardware peripherals across the ESP32-S3 as follows:
| Peripheral / Signal | GPIO | Mode / Hardware Interface | Description |
| :--- | :---: | :--- | :--- |
| **Rotary Encoder CLK** | `GPIO 32` | ESP-IDF `pulse_cnt` Unit | Quadrature channel A (hardware edge counter) |
| **Rotary Encoder DT** | `GPIO 33` | ESP-IDF `pulse_cnt` Unit | Quadrature channel B (direction sensing) |
| **Rotary Push Switch** | `GPIO 16` | Digital Input (`PULLUP`) | Rotary push-button (mode / parameter select) |
| **Button: Pause / Play** | `GPIO 13` | Digital Input (`PULLUP`) | Navigation / transport control |
| **Button: Next / Forward**| `GPIO 14` | Digital Input (`PULLUP`) | Navigation / channel advance |
| **Passive Buzzer** | `GPIO 25` | LEDC PWM (`LEDC_CHANNEL_0`) | Hardware PWM audio synthesis (frequency & melody) |
| **Active Buzzer 1** | `GPIO 26` | Digital Output | Percussive acoustic click / telemetry alert 1 |
| **Active Buzzer 2** | `GPIO 27` | Digital Output | Percussive acoustic click / telemetry alert 2 |
| **LED: Kick Trigger** | `GPIO 21` | Digital Output | Visual beat / primary telemetry indicator |
| **LED: Hat Trigger** | `GPIO 22` | Digital Output | Visual beat / secondary telemetry indicator |
| **OLED Data/Command (DC)**| `GPIO 2` | Digital Output | 1.3" OLED command vs data selection |
| **OLED Reset (RES)** | `GPIO 4` | Digital Output | Hardware display reset line |
| **OLED Chip Select (CS)** | `GPIO 5` | SPI Device Select (`SPI2`) | Display SPI bus enable |
| **OLED Clock (CLK)** | `GPIO 18` | SPI Master Clock (`SPI2`) | Hardware SPI clock line (DMA enabled) |
| **OLED MOSI** | `GPIO 23` | SPI Master Output (`SPI2`) | Hardware SPI data out line (DMA enabled) |
| **NeoPixel RGB Bar** | Config | RMT Peripheral | WS2812B 8-pixel addressable RGB telemetry strip |
---
## Repository Structure
```text
multi-functional-controller/
├── firmware/ # ESP-IDF C99/C++ Firmware Project
│ ├── CMakeLists.txt # Top-level CMake project configuration
│ ├── sdkconfig # ESP32-S3 configuration (PSRAM, Flash, FreeRTOS)
│ └── main/
│ ├── CMakeLists.txt # Component registration
│ ├── idf_component.yml # Espressif component dependencies (led_strip)
│ └── mmcontroller.c # Core firmware: FreeRTOS tasks, pulse counter, SPI OLED, LEDC PWM
├── hardware/ # KiCad 10 Electronic Design Automation (EDA)
│ ├── mfc-1.kicad_pro # KiCad project file
│ ├── mfc-1.kicad_sch # Complete schematic design & component symbols
│ └── mfc-1.kicad_pcb # Board layout & routing rules
├── images/ # High-resolution prototype photography
│ ├── TOP_VIEW.png # Front control surface overview
│ ├── SIDE_VIEW_WITH_ANTENNA.png # RF antenna and profile perspective
│ └── BOTTOM_VIEW.png # Perfboard underside bus wiring
├── .gitignore # Clean repository filter (builds, caches, local configs)
└── README.md # Master engineering documentation
```
---
## Getting Started: Building the Firmware
### Prerequisites
- [ESP-IDF v5.1+](https://docs.espressif.com/projects/esp-idf/en/latest/esp32s3/get-started/) installed and exported into your environment:
```bash
. $HOME/esp/esp-idf/export.sh
```
### Build & Flash
1. Navigate to the firmware directory:
```bash
cd firmware
```
2. Set target to ESP32-S3:
```bash
idf.py set-target esp32s3
```
3. Compile the firmware:
```bash
idf.py build
```
4. Flash to the controller and open serial monitoring:
```bash
idf.py -p /dev/ttyUSB0 flash monitor
```
*(Replace `/dev/ttyUSB0` with your serial device node, e.g. `/dev/ttyACM0`)*.
---
## Hardware CAD & Schematic Editing
The electronic schematic is developed in **KiCad 10**:
1. Open the project:
```bash
kicad hardware/mfc-1.kicad_pro
```
2. Inspect or modify the schematic in `eeschema` (`hardware/mfc-1.kicad_sch`).
3. To generate vector schematics for documentation or web publication:
- Select **File $\rightarrow$ Plot $\rightarrow$ SVG** or **PDF**.
---
## Roadmap & Milestones
- [x] Initial hardware breadboard and perfboard prototype (6×9 cm assembly).
- [x] Dual-core ESP-IDF firmware setup with FreeRTOS task scheduling.
- [x] Hardware pulse-counter integration for quadrature rotary encoder (`driver/pulse_cnt.h`).
- [x] Hardware LEDC PWM audio synthesis & percussive buzzer drivers.
- [x] High-speed SPI OLED graphics driver with DMA channel support.
- [x] Addressable WS2812B NeoPixel telemetry integration.
- [ ] Custom multi-layer printed circuit board (PCB) design in KiCad.
- [ ] 3D-printable ergonomic handheld enclosure (PETG / Resin).
- [ ] Low-latency NRF24L01+ bidirectional packet protocol with ACK-payload telemetry.
- [ ] Standard USB Gamepad HID descriptor integration for plug-and-play PC gaming.
---
## Author & Project Notebook
- **Author:** [Ertunç Özbay](https://github.com/ertunc-ozbay)
- **Personal Workshop & Portfolio:** [ertuncozbay.dev](https://ertuncozbay.dev)
- **Project Detail Page:** [ertuncozbay.dev/projects/multi-functional-controller.html](https://ertuncozbay.dev/projects/multi-functional-controller.html)
- **License:** [MIT License](LICENSE)