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ESP32 Robot Car - Connection Guide

Overview

This document provides detailed wiring instructions for connecting the ESP32, HC-06 Bluetooth module, BTS7960 motor drivers, and 12V motors for the robot car project.

Important Safety Notes

⚠️ CRITICAL: All GND (ground) connections must be connected together (common ground) ⚠️ Use separate power supplies for ESP32 (5V) and motors (12V) ⚠️ Double-check all connections before powering on ⚠️ Ensure proper polarity for all connections

Component Connections

1. HC-06 Bluetooth Module to ESP32

HC-06 Pin ESP32 Pin Description
VCC 3.3V Power supply (3.3V)
GND GND Ground (common)
TXD GPIO 16 Transmit data (HC-06 TX → ESP32 RX)
RXD GPIO 17 Receive data (HC-06 RX → ESP32 TX)

Note: HC-06 operates at 3.3V logic level, which is compatible with ESP32.

2. BTS7960 Left Motor Driver to ESP32

This driver controls the left side motors (2 motors connected in parallel).

BTS7960 Pin ESP32 Pin Description
VCC 5V Logic power supply
GND GND Ground (common)
L_EN GPIO 25 Left enable pin
R_EN GPIO 26 Right enable pin
LPWM GPIO 27 Left PWM signal (forward)
RPWM GPIO 14 Right PWM signal (backward)
M+ Motor + Positive terminal (2 left motors in parallel)
M- Motor - Negative terminal (2 left motors in parallel)
B+ 12V + Motor power supply positive
B- 12V - Motor power supply negative (common ground)

Motor Connection:

  • Connect both left motors in parallel: Motor1+ and Motor2+ → M+
  • Connect both left motors in parallel: Motor1- and Motor2- → M-

3. BTS7960 Right Motor Driver to ESP32

This driver controls the right side motors (2 motors connected in parallel).

BTS7960 Pin ESP32 Pin Description
VCC 5V Logic power supply
GND GND Ground (common)
L_EN GPIO 33 Left enable pin
R_EN GPIO 32 Right enable pin
LPWM GPIO 13 Left PWM signal (forward)
RPWM GPIO 12 Right PWM signal (backward)
M+ Motor + Positive terminal (2 right motors in parallel)
M- Motor - Negative terminal (2 right motors in parallel)
B+ 12V + Motor power supply positive (shared with left driver)
B- 12V - Motor power supply negative (common ground)

Motor Connection:

  • Connect both right motors in parallel: Motor3+ and Motor4+ → M+
  • Connect both right motors in parallel: Motor3- and Motor4- → M-

4. Power Supply Connections

ESP32 Power Supply

  • Option 1: USB cable connected to computer or USB power adapter (5V)
  • Option 2: 5V regulated power supply connected to 5V and GND pins
  • Current requirement: ~500mA typical

Motor Power Supply (12V Battery Pack)

  • Voltage: 12V DC
  • Current requirement: Depends on motor specifications (typically 2-5A per motor at full load)
  • Connection:
    • 12V battery positive (+) → B+ on both BTS7960 modules
    • 12V battery negative (-) → B- on both BTS7960 modules
    • IMPORTANT: Also connect 12V battery negative (-) to common GND

Complete Pin Summary

ESP32 GPIO Pin Assignments

GPIO Pin Function Component
16 RX HC-06 Bluetooth
17 TX HC-06 Bluetooth
12 RPWM Right BTS7960
13 LPWM Right BTS7960
14 RPWM Left BTS7960
25 L_EN Left BTS7960
26 R_EN Left BTS7960
27 LPWM Left BTS7960
32 R_EN Right BTS7960
33 L_EN Right BTS7960

Wiring Diagram (Text Representation)

                    ESP32
                    ┌─────┐
                    │     │
        3.3V ───────┤VCC  │
        GND ────────┤GND  │
                    │     │
                    │GPIO │
                    │ 16  │◄─── TXD (HC-06)
                    │ 17  │───► RXD (HC-06)
                    │     │
                    │ 25  │───► L_EN (Left BTS7960)
                    │ 26  │───► R_EN (Left BTS7960)
                    │ 27  │───► LPWM (Left BTS7960)
                    │ 14  │───► RPWM (Left BTS7960)
                    │     │
                    │ 33  │───► L_EN (Right BTS7960)
                    │ 32  │───► R_EN (Right BTS7960)
                    │ 13  │───► LPWM (Right BTS7960)
                    │ 12  │───► RPWM (Right BTS7960)
                    │     │
                    │ 5V  │───► VCC (Both BTS7960)
                    └─────┘

    Left BTS7960              Right BTS7960
    ┌──────────┐              ┌──────────┐
    │ M+  M-   │              │ M+  M-   │
    │  │   │   │              │  │   │   │
    │  └───┴───┼─── Left      │  └───┴───┼─── Right
    │          │    Motors    │          │    Motors
    │ B+  B-   │              │ B+  B-   │
    │  │   │   │              │  │   │   │
    └──┼───┼───┘              └──┼───┼───┘
       │   │                     │   │
       │   └─────────────────────┘   │
       │                             │
   12V Battery Pack                  │
    ┌──────────┐                     │
    │  +     - │─────────────────────┘
    └──────────┘
         │
         └───────────────────────────► Common GND

Connection Checklist

Before powering on, verify:

  • HC-06 VCC connected to ESP32 3.3V
  • HC-06 GND connected to ESP32 GND
  • HC-06 TXD connected to ESP32 GPIO 16
  • HC-06 RXD connected to ESP32 GPIO 17
  • Left BTS7960 VCC connected to ESP32 5V
  • Left BTS7960 GND connected to ESP32 GND
  • Left BTS7960 L_EN connected to ESP32 GPIO 25
  • Left BTS7960 R_EN connected to ESP32 GPIO 26
  • Left BTS7960 LPWM connected to ESP32 GPIO 27
  • Left BTS7960 RPWM connected to ESP32 GPIO 14
  • Right BTS7960 VCC connected to ESP32 5V
  • Right BTS7960 GND connected to ESP32 GND
  • Right BTS7960 L_EN connected to ESP32 GPIO 33
  • Right BTS7960 R_EN connected to ESP32 GPIO 32
  • Right BTS7960 LPWM connected to ESP32 GPIO 13
  • Right BTS7960 RPWM connected to ESP32 GPIO 12
  • Left motors (2) connected in parallel to Left BTS7960 M+ and M-
  • Right motors (2) connected in parallel to Right BTS7960 M+ and M-
  • 12V battery positive connected to B+ on both BTS7960 modules
  • 12V battery negative connected to B- on both BTS7960 modules
  • All GND connections are common (connected together)
  • ESP32 powered via USB or 5V supply
  • All connections are secure and properly insulated

Troubleshooting Connections

Motors not moving

  • Check if 12V battery is connected and has sufficient charge
  • Verify B+ and B- connections on BTS7960 modules
  • Check motor connections to M+ and M- terminals
  • Ensure common ground is properly connected

Motors running in wrong direction

  • Swap the M+ and M- connections on the affected motor driver
  • Or modify the code to reverse the direction logic

Bluetooth not connecting

  • Verify HC-06 VCC is connected to 3.3V (not 5V)
  • Check TXD/RXD connections (they should be crossed: TXD→RX, RXD→TX)
  • Ensure HC-06 is powered and LED is blinking

ESP32 not responding

  • Check 5V/USB power supply
  • Verify all GND connections are common
  • Check for short circuits

Additional Notes

  • The BTS7960 modules require both enable pins (L_EN and R_EN) to be HIGH for the motors to operate
  • PWM signals control motor speed (0-255 = 0-100% speed)
  • Motor direction is controlled by which PWM channel is active (LPWM for forward, RPWM for backward)
  • Always power off before making or changing connections
  • Use appropriate wire gauge for motor power connections (18-20 AWG recommended)