How to Use DRV 8825: Examples, Pinouts, and Specs

The DRV8825 is a stepper motor driver IC manufactured by Texas Instruments, designed to provide precise control of stepper motors. It supports adjustable current control, microstepping (up to 1/32 steps), and includes built-in protection features such as overcurrent, thermal shutdown, and undervoltage lockout. The DRV8825 is widely used in robotics, 3D printers, CNC machines, and other automation systems requiring accurate motor control.

• 3D printers and CNC machines
• Robotics and automation systems
• Camera sliders and gimbals
• Precision positioning systems
• DIY electronics projects

The DRV8825 is a versatile and robust stepper motor driver. Below are its key technical details:

The DRV8825 is typically available in a 28-pin HTSSOP package or as a breakout module. Below is the pinout for the breakout module:

The microstepping mode is configured using the MS1, MS2, and MS3 pins as shown below:

1. Power Supply: Connect VMOT to a power supply (8.2V to 45V) and GND to ground. Add a decoupling capacitor (e.g., 100 µF) across VMOT and GND to stabilize the power supply.
2. Motor Connections: Connect the stepper motor coils to AOUT1, AOUT2, BOUT1, and BOUT2. Ensure the correct pairing of motor wires.
3. Logic Connections: Connect VDD to the logic voltage (3.3V or 5V) and GND to the logic ground.
4. Control Pins: Connect STEP, DIR, ENABLE, and microstepping pins (MS1, MS2, MS3) to your microcontroller or control circuit.

To prevent overheating or overdriving the motor, adjust the current limit using the onboard potentiometer:

1. Measure the reference voltage (VREF) on the breakout board.
2. Use the formula:
   Current Limit = VREF × 2 (for most DRV8825 modules).
   For example, if VREF = 0.5V, the current limit is 1A.
3. Turn the potentiometer clockwise to increase the current limit or counterclockwise to decrease it.

Below is an example of how to control a stepper motor using the DRV8825 and an Arduino UNO:

// Define control pins
#define STEP_PIN 3  // Connect to STEP pin on DRV8825
#define DIR_PIN 4   // Connect to DIR pin on DRV8825

void setup() {
  pinMode(STEP_PIN, OUTPUT); // Set STEP pin as output
  pinMode(DIR_PIN, OUTPUT);  // Set DIR pin as output

  digitalWrite(DIR_PIN, HIGH); // Set initial direction
}

void loop() {
  // Generate step pulses
  digitalWrite(STEP_PIN, HIGH); // Step pulse HIGH
  delayMicroseconds(500);       // Wait 500 microseconds
  digitalWrite(STEP_PIN, LOW);  // Step pulse LOW
  delayMicroseconds(500);       // Wait 500 microseconds
}

• Use a heatsink or active cooling if driving motors at high currents.
• Avoid connecting or disconnecting the motor while the driver is powered to prevent damage.
• Ensure proper decoupling capacitors are in place to avoid voltage spikes.

1. Motor Not Moving:

   • Check the power supply connections and ensure VMOT and VDD are correctly powered.
   • Verify the STEP pin is receiving pulses from the microcontroller.
   • Ensure the motor coils are correctly connected to the driver.

2. Overheating:

   • Reduce the current limit using the potentiometer.
   • Add a heatsink or active cooling to the driver.

3. Fault Indicator (FAULT Pin Low):

   • Check for overcurrent or thermal shutdown conditions.
   • Ensure the motor is not drawing more current than the driver can handle.

4. Erratic Motor Movement:

   • Verify the microstepping mode configuration (MS1, MS2, MS3).
   • Check for loose or incorrect wiring.

Q: Can I use the DRV8825 with a 12V power supply?
A: Yes, the DRV8825 supports motor power supply voltages from 8.2V to 45V, so 12V is within the acceptable range.

Q: How do I know the correct current limit for my motor?
A: Refer to your motor's datasheet for its rated current per phase. Set the current limit on the DRV8825 to match or slightly below this value.

Q: Can I use the DRV8825 with a unipolar stepper motor?
A: The DRV8825 is designed for bipolar stepper motors. However, you can use a unipolar motor in bipolar mode by ignoring the center tap wires.

Q: What happens if I exceed the current limit?
A: The DRV8825 includes overcurrent protection and will shut down to prevent damage. However, prolonged overcurrent conditions can still cause overheating.

By following this documentation, you can effectively use the DRV8825 stepper motor driver in your projects.