Motor Driver Boards

Introduction

A motor driver board is the power electronics module that sits between the MCU and the motor. Since the MCU's GPIO output current (typically <20 mA) is insufficient to directly drive a motor (which typically requires hundreds of milliamps to tens of amps), the driver board handles power amplification and current direction control.

H-Bridge Principle

Basic Structure

The H-bridge is the core circuit for DC motor driving, consisting of 4 switches (MOSFETs or BJTs) arranged in an "H" shape:

    VCC
     │
  ┌──┴──┐
  │     │
 Q1     Q3
  │     │
  ├─ M ─┤     M = Motor
  │     │
 Q2     Q4
  │     │
  └──┬──┘
     │
    GND

Operating Modes

Q1	Q2	Q3	Q4	Motor State
ON	OFF	OFF	ON	Forward
OFF	ON	ON	OFF	Reverse
ON	OFF	ON	OFF	Braking (high-side short)
OFF	ON	OFF	ON	Braking (low-side short)
OFF	OFF	OFF	OFF	Free coast

Forbidden State

The upper and lower switches on the same side (Q1+Q2 or Q3+Q4) must never be turned on simultaneously; otherwise, the power supply is directly short-circuited, causing instant damage! Driver ICs typically include dead-time protection internally.

PWM Speed Control

Speed is controlled by applying a PWM signal to the H-bridge switches, regulating the average voltage:

\[ V_{avg} = V_{supply} \times \frac{D}{100\%} \]

Where \(D\) is the duty cycle. PWM frequency is typically chosen at 20–50 kHz (above human hearing range).

L298N Dual H-Bridge Driver Module

Specifications

Parameter	Value
Drive channels	2 (dual H-bridge)
Operating voltage	5–35V
Drive current	2A/channel (3A peak)
Logic voltage	5V (onboard regulator)
Control method	DIR + PWM or IN1/IN2/ENA
Package	Large DIP with heatsink

Wiring Diagram

                  ┌──────────────┐
 Motor A+ ────────┤ OUT1    +12V ├── Motor power (7-12V)
 Motor A- ────────┤ OUT2     GND ├── Common ground
 Motor B+ ────────┤ OUT3      5V ├── Can output 5V to MCU
 Motor B- ────────┤ OUT4         │
                  │              │
 Arduino D5 (PWM)─┤ ENA     ENB ├─ Arduino D6 (PWM)
 Arduino D2 ──────┤ IN1     IN3 ├─ Arduino D4
 Arduino D3 ──────┤ IN2     IN4 ├─ Arduino D7
                  └──────────────┘

Control Code

// L298N dual motor control
#define ENA 5   // PWM speed control
#define IN1 2   // Direction control
#define IN2 3
#define ENB 6
#define IN3 4
#define IN4 7

void motorA(int speed) {
    // speed: -255 ~ 255
    if (speed >= 0) {
        digitalWrite(IN1, HIGH);
        digitalWrite(IN2, LOW);
        analogWrite(ENA, speed);
    } else {
        digitalWrite(IN1, LOW);
        digitalWrite(IN2, HIGH);
        analogWrite(ENA, -speed);
    }
}

void motorB(int speed) {
    if (speed >= 0) {
        digitalWrite(IN3, HIGH);
        digitalWrite(IN4, LOW);
        analogWrite(ENB, speed);
    } else {
        digitalWrite(IN3, LOW);
        digitalWrite(IN4, HIGH);
        analogWrite(ENB, -speed);
    }
}

Limitations

Low efficiency (BJT voltage drop ~2V, high power dissipation and heat)
Suitable for low-power beginner projects; not recommended for production robots

TB6612FNG

Specifications

Parameter	Value
Drive channels	2
Operating voltage	2.5–13.5V
Drive current	1.2A/channel (3.2A peak)
Logic voltage	2.7–5.5V
On-resistance	0.5 ohm (MOSFET)
Standby mode	Yes (STBY pin)
Package	Small SSOP24

Advantages

MOSFET-based driver with very low voltage drop (~0.5V vs. 2V for L298N), high efficiency
Compact form factor, suitable for tight designs
Supports PWM frequencies up to 100 kHz
Built-in thermal shutdown protection

Wiring

TB6612FNG    MCU
AIN1    ←── GPIO (direction)
AIN2    ←── GPIO (direction)
PWMA    ←── PWM  (speed)
BIN1    ←── GPIO
BIN2    ←── GPIO
PWMB    ←── PWM
STBY    ←── GPIO (HIGH=active)
VM      ←── Motor power
VCC     ←── Logic power (3.3/5V)
GND     ←── Common ground
AO1/AO2 ──→ Motor A
BO1/BO2 ──→ Motor B

Waveshare General Driver for Robots

Overview

The Waveshare General Driver for Robots integrates multiple interfaces into a single board.

Specifications

Parameter	Value
MCU	ESP32-S3
DC motor drivers	4 channels (TB6612)
Servo interfaces	Multiple PWM channels
Bus servos	Supports STS/Dynamixel
Display	0.91" OLED
IMU	Onboard 6-axis
Communication	WiFi/BLE/UART/I2C/SPI
Power	USB-C + battery connector

Features

One board addresses all driving needs for small robots
ESP32-S3 supports WiFi and BLE for remote control
Onboard OLED displays status information
Dual MicroPython and Arduino support

Suitable Scenarios

Wheeled cars
Small robotic arms
Educational robot platforms
Rapid prototyping

ODrive S3

Overview

ODrive is an open-source, high-performance BLDC driver for robotics and automation applications.

Specifications

Parameter	Value
Drive channels	Dual-channel BLDC
Voltage range	12–56V
Continuous current	40A/channel
Peak current	80A/channel
Control algorithm	FOC (sinusoidal)
Current loop bandwidth	>5 kHz
Encoder	Incremental / SPI / Hall / Sensorless
Communication	USB / CAN / UART / SPI / GPIO
Processor	STM32F405

Feature Highlights

Current/velocity/position triple-loop closed-loop control
Supports trapezoidal and S-curve trajectory planning
Built-in anti-cogging calibration
ASCII and Native protocols
Open-source firmware, customizable

CAN Bus Multi-Axis Control

# ODrive CAN multi-axis control example
import can

bus = can.interface.Bus(channel='can0', bustype='socketcan')

def set_position(node_id, position):
    """Set ODrive position via CAN"""
    # Set Input Pos command: cmd_id = 0x00C
    arbitration_id = (node_id << 5) | 0x00C
    data = struct.pack('<fhh', position, 0, 0)  # pos, vel_ff, torque_ff
    msg = can.Message(arbitration_id=arbitration_id, data=data)
    bus.send(msg)

# Control two axes
set_position(0, 10.0)  # Axis 0: 10 turns
set_position(1, -5.0)  # Axis 1: -5 turns

Pololu Motor Drivers

Pololu offers a variety of small, high-quality motor driver modules:

Common Models

Model	Current	Voltage	Features
DRV8833	1.2A	2.7–10.8V	Dual-channel, ultra-compact
DRV8838	1.8A	0–11V	Single-channel, minimal
TB6612FNG	1.2A	4.5–13.5V	Dual-channel, classic
VNH5019	12A	5.5–24V	Single-channel, high current
G2 18v17	17A	6.5–30V	High current, high performance

Selection Reference

Motor current requirement:
  < 1A  ──→ DRV8833 / TB6612FNG
  1-5A  ──→ BTS7960 / L298N
  5-15A ──→ VNH5019 / G2 series
  > 15A ──→ ODrive / Custom MOSFET driver

Driver Board Wiring Considerations

Power Supply

Separate motor and logic power: Prevent motor noise from interfering with the MCU
Thick power wires: Use 16–18 AWG wire for high-current scenarios
Decoupling capacitors: Add large capacitors (100 uF–1000 uF) across the driver board power input
Flyback diodes: Inductive motor loads produce reverse voltage when de-energized; driver ICs usually include these internally

Grounding

Battery ─┬─→ Motor driver board ──→ Motor
         │        │
         │    Common GND ←── This connection must be reliable
         │        │
         └─→ Buck converter ──→ MCU

Common Ground Principle

The MCU and driver board GND must be connected; otherwise, logic signals have no reference level, and the driver board cannot correctly interpret PWM and direction signals.

EMI Protection

Add 0.1 uF ceramic capacitors across motor terminals (suppresses brush sparking)
Use shielded or twisted-pair cables to connect motors
Choose PWM frequencies that avoid communication frequency bands

Driver Solution Comparison

Solution	Motor Type	Current	Cost	Suitable Scenario
L298N	Brushed DC	2A	Low	Beginner/educational
TB6612FNG	Brushed DC	1.2A	Low	Small robots
BTS7960	Brushed DC	43A	Medium	Large chassis
Waveshare General	DC + Servo	1.2A	Medium	Integrated small robots
ESC	BLDC	Varies	Medium	Drones
ODrive S3	BLDC	40A	High	Robot joints
Industrial servo drive	AC Servo	Varies	High	Industrial robots

Summary

The H-bridge is the fundamental DC motor driving circuit, using 4 switches to control current direction
The L298N is suitable for beginners but has low efficiency; the TB6612FNG is a better alternative
The Waveshare General Driver integrates ESP32 + motors + servos, suitable for small robots
ODrive is a high-performance open-source BLDC driver supporting FOC and CAN bus
Driver board selection primarily depends on current capacity, voltage range, and control method
Power supply design, common grounding, and EMI protection are critical for reliable operation

Motor Driver Boards

Introduction

H-Bridge Principle

Basic Structure

Operating Modes

PWM Speed Control

L298N Dual H-Bridge Driver Module

Specifications

Wiring Diagram

Control Code

Limitations

TB6612FNG

Specifications

Advantages

Wiring

Waveshare General Driver for Robots

Overview

Specifications

Features

Suitable Scenarios

ODrive S3

Overview

Specifications

Feature Highlights

CAN Bus Multi-Axis Control

Pololu Motor Drivers

Common Models

Selection Reference

Driver Board Wiring Considerations

Power Supply

Grounding

EMI Protection

Driver Solution Comparison

Summary

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