SA8302 Stepper Motor Driver Module

Introduction

The SA8302 is a high-performance motor driver module specifically designed to replace the traditional ULN2003. Utilizing modern Power MOSFET technology (PMOS+NMOS) instead of outdated Darlington transistors, it offers significantly lower heat generation, higher efficiency, and a more compact form factor.

Why Upgrade from ULN2003 to SA8302?

Feature	SA8302	ULN2003	Advantage
Architecture	Modern Power MOSFET	Darlington Transistors	Minimal heat, much higher efficiency
Voltage Drop	Ultra-low (400mΩ resistance)	High (approx. 0.9V - 1.5V)	Higher torque and output power
Standby Power	0.1μA (Ultra-low)	Milliampere range	Battery friendly, extends project life
Continuous Current	1.0A per Channel (3A Peak)	500mA per Channel	Stronger drive for heavy-duty tasks
Protection	OTP & UVLO Included	None	Higher reliability, prevents burnout

Technical Specifications

• Operating Voltage: 2V – 7V (Typical: 5V)
• Continuous Output Current:
• Stepper Mode: Up to 1A Phase Current
• DC Mode: 1A per channel (Dual channels)
• Peak Output Current: 3A (Instantaneous surge)
• On-Resistance: 400mΩ (HS+LS)
• Quiescent/Standby Current: 0.1μA
• Protection Features: Over-Temperature Protection (OTP), Under-Voltage Lockout (UVLO)

⚠️ IMPORTANT: This module supports either ONE Stepper Motor OR TWO DC Motors at a time; they cannot be controlled simultaneously.

Schematics

Download SA8302 Module Schematics files (PDF)

Mechanical Dimensions

• Board Size: 38.4 mm × 22.4 mm
• Mounting Hole Spacing: 15.2 mm (Horizontal) / 16 mm (Vertical)
• Hole Diameter: 4.7 mm (Compatible with standard M4 screws/standoffs)

Driving DC Motor in Arduino

// Define Control Pins for Motor Channel A & B
#define INA 5  
#define INB 6  

// Define Control Pins for Motor Channel C & D
#define INC 9  
#define IND 10 

void setup() {
    // Set all motor control pins as OUTPUT
    pinMode(INA, OUTPUT);  
    pinMode(INB, OUTPUT);
    pinMode(INC, OUTPUT);  
    pinMode(IND, OUTPUT);  
}

void loop() {
    // --- Step 1: Motors Rotate Forward ---
    analogWrite(INA, 255);  // Set Port A HIGH
    analogWrite(INB, 0);    // Set Port B LOW
    analogWrite(INC, 255);  // Set Port C HIGH
    analogWrite(IND, 0);    // Set Port D LOW

    delay(2000);            // Wait for 2 seconds

    // --- Step 2: Motors Reverse Direction ---
    analogWrite(INA, 0);    // Set Port A LOW
    analogWrite(INB, 255);  // Set Port B HIGH
    analogWrite(INC, 0);    // Set Port C LOW
    analogWrite(IND, 255);  // Set Port D HIGH

    delay(2000);            // Reverse for 2 seconds, then repeat loop
}

Driving the 28BYJ-48 Stepper Motor

This module is perfectly compatible with the 28BYJ-48 4-phase 5-wire stepper motor, commonly used in DIY robotics.

The "28BYJ-48" follows a specific naming convention: "28" indicates a maximum outer diameter of 28mm, while "B" identifies it as a Stepper Motor. "Y" signifies a Permanent Magnet type, and "J" denotes a Geared motor with a 1:64 reduction ratio. Finally, "48" indicates its compatibility with 4-beat or 8-beat drive sequences.

Connection

The board features a standard XH2.54 5-pin interface. Simply plug the white 5-wire connector of the 28BYJ-48 motor directly into the onboard socket. No soldering or extra wiring is required.

Core Development Parameters

The 28BYJ-48 specifications:

• Stride Angle: 5.625° × 1 / 64 (Reduction ratio 1:64)
• Steps per Revolution (Internal): 64
• Total Steps for 360° Output: 4096 steps (64 × 64)
• Performance: Due to the low voltage drop of the SA8302, the motor achieves higher torque (>300g.cm) and runs cooler than when used with standard ULN2003 drivers.

Calculation & Programming Logic

According to the specification, the stepper motor has a stride angle of 5.625°. Therefore, the number of steps per internal revolution is 360° / 5.625° = 64. Thus, the STEPS parameter is set to 64.

// Initialization: STEPS (steps per internal revolution), pin1, pin2, pin3, pin4 
Stepper stepper(STEPS, pin1, pin2, pin3, pin4);

Speed Configuration

// Sets the motor speed in RPM (Revolutions Per Minute)
stepper.setSpeed(SPEED); 

When setting the speed (e.g., setSpeed(200)), please note that this value refers to the internal motor speed before the gear reduction. Due to the 1:64 gear ratio, the actual output shaft speed will be:

speed = 200/64 = 3.125 rpm

Full Rotation Calculation

To achieve one complete 360° rotation of the output shaft, the total number of steps required is:

steps = (360/5.625)*64 = 4096

Wiring Diagram

The module is controlled via four logic signals: INA, INB, INC, and IND.

SA8302 Pin	Arduino Uno Pin	ESP32 Pin	Function Description
G	GND	GND	Power Ground
V	5V	5V	Power Supply (2-7V)
INA	5	17	Input A (Stepper Phase A)
INB	6	16	Input B (Stepper Phase B)
INC	9	15	Input C (Stepper Phase C)
IND	10	14	Input D (Stepper Phase D)

Example Code

Download Arduino Examples

Download ESP32 MicroPython Examples

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