Project summary

RC-Controller is a compact ESP32-based remote controller for radio-controlled vehicles and projects. It reads two analog joysticks and two thin-film pressure sensors, packages the data into a small Payload struct, and sends it over an nRF24L01 transceiver. The codebase is intended to be minimal, easy to adapt, and friendly to PlatformIO and Arduino IDE users.

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Status

• Hardware:  ESP32-WROOM-32D
• Firmware: Working basic telemetry and transmit path implemented

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Features

• Reads two full analog joysticks (HW-504 compatible wiring)
• Two analog thin-film pressure sensors for triggers
• Debounced push buttons (joystick switches) using INPUT_PULLUP
• Packets transmitted via nRF24L01 using RF24 library
• Simple, single-file payload definition for easy receiver integration

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Hardware (what I used)

• MCU: ESP32-WROOM-32D (other ESP32 modules with similar pinouts will work but may need pin adjustments)
• Joysticks: HW-504 (two units). Other joysticks OK if they follow the same pinout (two analog axes + push switch).
• Triggers / pressure sensors: 2× thin-film resistive sensors (10 kg) wired as voltage dividers with a 10K pull-down resistor.
• Radio: nRF24L01 (2.4 GHz transceiver)
• Power: 3.3V supply for ESP32 and nRF24L01 (nRF24 modules are sensitive to supply noise, add decoupling or a separate regulator if unstable)

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Pinout (from CONFIG.hpp)

• JOY1_VRx_PIN — GPIO36 (analog) — Joystick 1 X

• JOY1_VRy_PIN — GPIO39 (analog) — Joystick 1 Y

• JOY1_SW_PIN — GPIO25 (digital input, INPUT_PULLUP) — Joystick 1 push button

• JOY2_VRx_PIN — GPIO34 (analog) — Joystick 2 X

• JOY2_VRy_PIN — GPIO35 (analog) — Joystick 2 Y

• JOY2_SW_PIN — GPIO26 (digital input, INPUT_PULLUP) — Joystick 2 push button

• PRESS_SENSOR_1_PIN — GPIO33 (analog) — Pressure sensor 1

• PRESS_SENSOR_2_PIN — GPIO32 (analog) — Pressure sensor 2

• NRF_CE_PIN — GPIO2 — nRF24L01 CE

• NRF_CSN_PIN — GPIO15 — nRF24L01 CSN (chip select)

Note: These pin assignments come directly from the project CONFIG.hpp. If you change the board or wiring, update that header.

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Payload struct

The code uses a packed Payload structure defined in CONFIG.hpp that contains the following fields:

struct Payload {
  int16_t joy1X;
  int16_t joy1Y;
  bool joy1Button;
  int16_t joy2X;
  int16_t joy2Y;
  bool joy2Button;
  int16_t pressSens1;
  int16_t pressSens2;
};

• Analog reads on the ESP32 return 0–4095 by default. The project stores those raw values into int16_t fields — be mindful of range if you change data types or add mapping/scaling.

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Wiring notes

• Joysticks (HW-504): typically expose VRx, VRy (two potentiometer outputs) and a push switch. Connect VRx/VRy to the analog pins above, switch to the configured digital pin (with INPUT_PULLUP in software), and Vcc/GND to 3.3V/GND.

• Thin-film pressure sensors (flexible FSR style): wired as voltage dividers. One side of the sensor goes to 3.3V, the other side goes to a junction that connects to the ESP32 analog input through a 10K resistor; the junction also connects to ground through the 10K resistor. This creates a readable analog voltage proportional to applied pressure. (The project’s sensors are described: one side positive, the other to a junction with 10K to ground and the analog line in between.)

• nRF24L01: use the module’s 3.3V pin (NOT 5V) and provide sufficient decoupling (a 10µF electrolytic across Vcc and GND near the module is recommended). Connect CE to NRF_CE_PIN and CSN to NRF_CSN_PIN. SCK, MOSI, MISO use the ESP32's hardware SPI pins (default SPI pins on most ESP32 dev modules).

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Software / libraries

• Firmware is written for the Arduino framework on ESP32.
• Uses RF24 (nRF24) library for nRF24L01 communication.
• Compatible with both PlatformIO and the Arduino IDE. Example platformio.ini snippet is included in SETUP.md.

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How to use

1. Follow the setup instructions in SETUP.md to install dependencies, configure, and flash the firmware.
2. Power the controller and ensure the receiver is configured with the same nRF24L01 address (const byte address[6] = "9TfT0" in main.cpp) and packet structure.
3. Use the serial monitor at 115200 baud for debug output (the sketch initializes Serial.begin(115200) in setup).

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Calibration & mapping

• The code currently sends raw analog values. You may want to map those values to a smaller range (e.g., -1000..1000 or -127..127) on either the controller or the receiver depending on your receiver code.
• Add deadzones to joystick axes in joystickHandler if you observe jitter around center.

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Troubleshooting

• Radio not transmitting: confirm CE/CSN wiring, correct address on receiver, and that the nRF24L01 has a stable 3.3V supply. Add a capacitor across Vcc/GND near the module.
• Noisy analog reads: add a small delay, remove long signal wires, add shielding, or put a small RC filter on analog lines. Consider averaging multiple reads.
• Buttons read inverted: code uses INPUT_PULLUP, so LOW typically means pressed.

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Contribution & license

This project is my personal project and I’m the solo developer. If you want collaboration, open an issue or a PR. Include a clear description and test steps.

LGPLv3. See LICENSE.md for details.

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Future work / TODO

• Add buttons
• Add CRC/checksum to payload
• KiCad schematics and PCB layout