Multi-Functional Controller (MFC)

A custom, modular remote controller and telemetry station engineered from scratch for long-range, low-latency 2.4 GHz RC control and USB/Bluetooth HID gaming.

Built around the ESP32-S3-N16R8 (Xtensa® 32-bit LX7 dual-core @ 240 MHz), this project is developed in structured hardware phases—starting from a hand-wired 6×9 cm perfboard carrier core and scaling into a full desktop/console transmitter housed in a DT-100 (190 × 137 × 59 mm) instrument enclosure.

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Phase 1: Core Carrier Board Showcase (Current Build)

The current physical hardware implements the Core MCU & RF Carrier Stage on a 6×9 cm perfboard:

• ESP32-S3-N16R8 Microcontroller (socketed on female headers)
• nRF24L01+ 2.4 GHz RF Transceiver Module with external dipole SMA antenna
• 100 µF Electrolytic Decoupling Capacitor (C1) across the 3.3V/GND radio rails to suppress TX burst voltage droop
• Modular Male Pin Headers & Dedicated Power Rail Headers for external display, encoder, and joystick breakout interfacing

Figure 1: Phase 1 Top View — ESP32-S3-N16R8 module, nRF24L01+ RF transceiver, 100 µF bulk decoupling capacitor, peripheral male pin headers, and dedicated power rail male headers on a 6×9 cm perfboard.

Figure 2: Phase 1 Side Profile — 2.4 GHz external dipole antenna mounted to the nRF24L01+ module and dual USB-C ports (Native USB-OTG & UART).

Figure 3: Phase 1 Underbody Bus Routing — Point-to-point solder bridges, common ground/power rails, and FSPI signal routing between the ESP32-S3-N16R8 and male breakout headers.

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Phase 2: Console Expansion Bill of Materials (BOM)

The project is transitioning from the bare perfboard carrier into a self-contained console transmitter. Below is the complete English technical specification for the Phase 2 hardware expansion:

Category	Component (English Technical Name)	Original / Part Spec	Engineering Role in Controller
Enclosure	DT-100 Desktop Instrument Enclosure (Black ABS)	DT-100 (190 × 137 × 59 mm)	Main desktop/handheld transmitter chassis housing the perfboard, dual gimbals, screen, and battery pack.
Display	1.3" ST7789 IPS TFT Color LCD Module	240 × 240 px, RGB SPI, 3.3V	High-contrast full-color IPS graphical dashboard replacing the benchtop monochrome OLED.
Primary Input	2× Dual-Axis Hall-Effect Analog Joysticks	Contactless Magnetic 2-Axis	Drift-free 4-channel analog control (Throttle, Yaw, Pitch, Roll) routed to ADC1.
Audio Input	MAX4466 Electret Microphone Amplifier Module	Adjustable Gain, 2.4V–5.5V	Analog voice telemetry capture and real-time audio FFT spectrum visualization on ADC1.
Storage	SPI MicroSD Card Reader Module	Standard SPI (MOSI/MISO/SCK/CS)	Non-volatile storage for flight/drive telemetry logs, model profiles, and UI bitmap assets.
Power Boost	MT3608 2A Adjustable DC-DC Step-Up Boost Converter	2V–24V Input, up to 28V / 2A Out	Boosts the 3.7V Li-ion battery rail to 5V / 12V for auxiliary peripherals and switch LED illumination.
Master Switch	12–24V Illuminated Waterproof Push-Button Switch	Latching ON-OFF, White LED Ring	Master system power / RF arming switch mounted on the DT-100 front panel.
Mode Switch	KTS-303 Mini Toggle Switch (3-Pin SPDT)	ON-OFF, Panel Mount	Physical toggle switch for flight/drive mode selection or high/low rate switching.
Aux Switch	180° Vertical Slide Switch	ON-OFF Slide, Through-Hole	Sub-circuit power rail isolation / programming mode selector.
Power Diode	1N5817 Schottky Barrier Diode	1A, 20V, DO-41 THT	Low forward-voltage drop (V_F \approx 0.45\text{V}) power rail OR-ing and reverse-polarity protection.
Rectifier Diode	1N4001 General-Purpose Silicon Diode	1A, 50V, DO-41 THT	Reverse-current blocking and inductive flyback protection across switched loads.
Switching BJT	2N2222 NPN Bipolar Junction Transistor	40V, 600mA–800mA, TO-92	Low-side transistor switch allowing 3.3V ESP32-S3 GPIOs to drive the 12V switch LED ring (via MT3608) or buzzers.

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Verified Pin Mapping (Phase 1 Firmware & Bench Harness)

The master firmware (firmware/main/mmcontroller.c) configures a collision-free shared SPI2_HOST (FSPI) bus, ADC1 analog inputs, and the hardware pulse_cnt quadrature decoder:

Peripheral / Signal	GPIO	Hardware Interface	Description
SPI Bus: MOSI	GPIO 11	SPI Master Output (SPI2_HOST)	Shared data line for nRF24L01+, Display (SDA), and MicroSD
SPI Bus: MISO	GPIO 13	SPI Master Input (SPI2_HOST)	Shared data input line from nRF24L01+ and MicroSD
SPI Bus: SCK (Clock)	GPIO 12	SPI Master Clock (SPI2_HOST)	Shared clock line for nRF24L01+, Display (CLK), and MicroSD
nRF24L01+ Chip Select (CS)	GPIO 14	SPI Device Select	Dedicated radio bus enable
nRF24L01+ Chip Enable (CE)	GPIO 21	Digital Output	Radio TX/RX power state activation line
Display Chip Select (CS)	GPIO 10	SPI Device Select	Display SPI bus enable
Display Data/Command (DC)	GPIO 9	Digital Output	Display command vs. frame data selection
Display Reset (RES)	GPIO 8	Digital Output	Hardware display reset line
Joystick 1 VRx (X-Axis)	GPIO 4	ADC1 Channel 3 (12 dB Atten)	Analog X-axis input (0–3.3V safe)
Joystick 1 VRy (Y-Axis)	GPIO 5	ADC1 Channel 4 (12 dB Atten)	Analog Y-axis input (0–3.3V safe)
Rotary Encoder CLK	GPIO 15	ESP-IDF pulse_cnt Unit	Quadrature channel A (hardware edge counter)
Rotary Encoder DT	GPIO 16	ESP-IDF pulse_cnt Unit	Quadrature channel B (direction sensing)
Rotary Encoder Switch (SW)	GPIO 17	Digital Input (PULLUP)	Push-button (menu enter/select mode)

Silicon Multiplexing Notes (ESP32-S3-N16R8 vs. Classic ESP32)

1. Octal PSRAM & Flash Reservation (GPIO 26 – GPIO 37): On the ESP32-S3-N16R8 (8 MB Octal PSRAM), GPIO 26 through GPIO 37 are wired internally to the Octal SPI Flash/PSRAM bus. Accessing GPIO 26, 27, 32, 33 triggers an immediate Guru Meditation Error / Cache Disabled Panic on boot.
2. Unbonded Silicon Pins (GPIO 22 – GPIO 25): GPIO 22, 23, 24, 25 do not exist on the ESP32-S3 pin multiplexing matrix.
3. FSPI (SPI2_HOST) Default Matrix: Uses native ESP32-S3 FSPI pins (GPIO 10, 11, 12, 13) rather than legacy 2016 ESP32 VSPI defaults (GPIO 5, 18, 23).

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Repository Structure

multi-functional-controller/
├── firmware/                        # ESP-IDF C99 Firmware Project (ESP32-S3)
│   ├── CMakeLists.txt               # Top-level CMake project configuration
│   ├── sdkconfig                    # Verified ESP32-S3 target configuration
│   └── main/
│       ├── CMakeLists.txt           # Component registration
│       └── mmcontroller.c           # Master firmware: Shared SPI2, Display UI, nRF24L01+, PCNT, ADC1
├── hardware/                        # KiCad 10 Electronic Design Automation (EDA)
│   ├── mfc-1.kicad_pro              # KiCad project file
│   ├── mfc-1.kicad_sch              # Phase 1 schematic design (ESP32-S3, nRF24L01+, 100uF cap)
│   └── mfc-1.kicad_pcb              # Board layout & routing rules
├── images/                          # High-resolution Phase 1 prototype photography
│   ├── TOP_VIEW.png                 # Perfboard top view (MCU, RF, 100uF cap, male pin headers)
│   ├── SIDE_VIEW_WITH_ANTENNA.png   # RF antenna and profile perspective
│   └── BOTTOM_VIEW.png              # Perfboard underside solder bus & power rail wiring
├── .gitignore                       # Clean repository filter (builds, caches, local configs)
├── LICENSE                          # MIT License
└── README.md                        # Master engineering documentation

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Getting Started: Building the Firmware

. $HOME/esp/esp-idf/export.sh
cd firmware
idf.py set-target esp32s3
idf.py build
idf.py -p /dev/ttyACM0 flash monitor

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Project Status & Roadmap

• Phase 1 Hardware (Complete): 6×9 cm perfboard carrier assembly with ESP32-S3-N16R8, nRF24L01+ RF module, 100 µF decoupling capacitor, signal male headers, and power rail male headers.
• Phase 1 Firmware (Complete): Shared SPI2_HOST bus, 5×8 UI state machine (DRIVE VEHICLE, RADIO CONFIG, CALIBRATE, SYSTEM INFO), hardware pulse_cnt rotary decoding, and live nRF24 channel tuning (0–125).
• Phase 2 Hardware Integration (In Progress):
  • Mount system into DT-100 (190 × 137 × 59 mm) black desktop enclosure.
  • Integrate 2× Dual-Axis Hall-Effect Joysticks (ADC1 channels GPIO 4, 5, 6, 7).
  • Upgrade display to 1.3" ST7789 240×240 IPS TFT LCD.
  • Wire MT3608 DC-DC Boost Converter, 1N5817 / 1N4001 Diodes, and 2N2222 NPN BJT to drive the 12–24V Illuminated Push-Button Switch, KTS-303 Toggle Switch, and 180° Slide Switch.
  • Integrate MAX4466 Microphone Amplifier and SPI MicroSD Card Module.
• Phase 3 Custom PCB: Full multi-layer PCB fabrication in KiCad 10.

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Author & Project Notebook

• Author: Ertunç Özbay
• Personal Workshop & Portfolio: ertuncozbay.dev
• Project Detail Page: ertuncozbay.dev/projects/multi-functional-controller.html
• License: MIT License