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🚗 ESP32 RC Car using ESP-NOW (Transmitter + Receiver)

A fully wireless RC-car system built using two ESP32 boards, two BTS7960 high-current motor drivers, and ESP-NOW for ultra-fast and low-latency communication.

This project supports:

✔ Analog joystick steering ✔ Potentiometer-based speed control ✔ Button input ✔ Differential motor control ✔ Automatic failsafe (motors stop if signal is lost) ✔ Expandable multi-channel design

🧩 Project Overview

This system has two ESP32 boards:

1️⃣ Transmitter ESP32

  • Reads joystick X/Y
  • Reads potentiometer (speed control)
  • Reads joystick switch button
  • Sends the values wirelessly to the receiver using ESP-NOW

2️⃣ Receiver ESP32

  • Receives joystick data
  • Processes differential drive (left/right motors)
  • Controls two BTS7960 motor drivers
  • Automatically stops motors if transmitter signal is lost

📦 Hardware Required

🔹 Transmitter Side

Component Qty
ESP32 Dev Board 1
2-axis Joystick Module 1/2
Potentiometer (10k recommended) 1
Jumper wires Several
5V power bank / Li-ion battery 1

🔹 Receiver / RC Car Side

Component Qty
ESP32 Dev Board 1
BTS7960 Motor Driver 2 (Left + Right motor)
12V–24V battery for motors 1
DC motors (high torque) 2
Chassis + wheels 1 set
Jumper wires (thick wires for motors) Several

🕹️ Transmitter Wiring

Joystick

Joystick Pin ESP32 Pin
VRX GPIO34
VRY GPIO35
SW GPIO32
+5V 3.3V/5V
GND GND

Potentiometer

Pot Pin ESP32 Pin
Middle Output GPIO33
One Side 3.3V/5V
Other Side GND

🚗 Receiver Wiring (BTS7960 + Motors)

Motor Driver 1 – LEFT Motor

BTS7960 Pin ESP32 Pin
RPWM GPIO25
LPWM GPIO26
R_EN GPIO27
L_EN GPIO14

Motor Driver 2 – RIGHT Motor

BTS7960 Pin ESP32 Pin
RPWM GPIO12
LPWM GPIO13
R_EN GPIO15
L_EN GPIO2

BTS7960 Power

  • B+ → Motor Battery +
  • B− → Motor Battery −
  • Motor terminals → actual motor

⚠️ Never power motors from ESP32 5V — BTS takes a separate supply.

🛰️ ESP-NOW Pairing (IMPORTANT)

🟦 Step 1 — Get the Receiver’s MAC Address

Upload the receiver code first.

Open Serial Monitor → it prints:

Receiver MAC Address: 80:F3:DA:55:8C:48
COPY THIS MAC ADDRESS TO TRANSMITTER CODE!

🟦 Step 2 — Add MAC to Transmitter Code

In the transmitter code, replace:

uint8_t receiverMAC[] = {0x80, 0xF3, 0xDA, 0x55, 0x8C, 0x48};

with your own receiver’s MAC.

If this is wrong → transmitter will NOT connect.

📡 How the System Works

🕹️ Transmitter

  • Reads joystick X/Y (0–4095)
  • Converts to −100 … +100 range
  • Reads potentiometer → 0–100 speedLevel
  • Packs into a struct:
struct_message {
  int xAxis;
  int yAxis;
  int speedLevel;
  bool button;
};
  • Sends to receiver via ESP-NOW every 50ms

🚗 Receiver

  • Gets the struct and extracts X/Y/speed values

  • Calculates:

    • Forward/backward speed (Y axis)
    • Left/right steering adjustment (X axis)

  • Uses differential drive:

    • Left motor speed adjusted opposite of right motor

  • Speed converted to PWM (0–255)

  • Controls motors through BTS7960 PWMs

  • Timeout protection stops motors if no signal for 1 sec

📡 Transmitter Code Explanation

1. Reads Joystick + Pot

int rawX = analogRead(JOYSTICK_X_PIN);
int rawY = analogRead(JOYSTICK_Y_PIN);
int rawP = analogRead(POT_PIN);

2. Convert joystick raw values to a usable −100 to +100 range

x = map(rawX, 0, 4095, -100, 100);

3. Apply deadzone

Removes jitter around the center.

4. Send Data via ESP-NOW

esp_now_send(receiverMAC, (uint8_t*)&myData, sizeof(myData));

🚗 Receiver Code Explanation

1. ESP-NOW receive callback

Triggered every time transmitter sends data.

void OnDataRecv(...)  
{
  memcpy(&incomingData, incomingDataByte, sizeof(incomingData));
  controlMotors(...);
}

2. Differential drive calculation

leftMotorSpeed = map(yAxis, -100, 100, -baseSpeed, baseSpeed);
rightMotorSpeed = map(yAxis, -100, 100, -baseSpeed, baseSpeed);

3. Steering adjustments

if (xAxis < 0) { turn left }
if (xAxis > 0) { turn right }

4. Apply to BTS7960

Forward:

analogWrite(RPWM, speed);
analogWrite(LPWM, 0);

Backward:

analogWrite(LPWM, speed);
analogWrite(RPWM, 0);

5. Signal loss protection

If no packet is received for 1 second → motors stop.

🚀 Future Improvements

Here are things you can add later (easy upgrades):

🔹 1. Extra Channels

  • Add headlights using LED
  • Horn/buzzer
  • Servo for camera pan/tilt
  • Extra buttons for custom features

Just expand the struct:

int extra1;
int extra2;
bool sw2;

🔹 2. FPV Camera System

Add ESP32-CAM or analog FPV system.

🔹 3. OLED Display on Transmitter

  • Show speed
  • Battery status
  • Signal strength

🔹 4. Telemetry Return Channel

Receiver → Transmitter Send:

  • Battery voltage
  • Motor temperature
  • Distance sensor values

🔹 5. Add PID Motor Control

Smoothen movement and avoid jerkiness.

🧪 Testing Tips

  • Always test motors with wheels lifted first
  • Expect the joystick Y-axis to control forward/back
  • X-axis controls left/right turning
  • Potentiometer smoothens speed