How to Use Motor Driver and Power Distribution Board for Romi Chassis: Examples, Pinouts, and Specs

The Pololu Motor Driver and Power Distribution Board for Romi Chassis (Part ID: 3543) is a specialized circuit board designed to control the motors of the Romi chassis while efficiently distributing power to other components. This board integrates motor driver functionality with power management, making it an essential component for robotics projects using the Romi chassis. It simplifies the process of powering and controlling motors, sensors, and other peripherals, ensuring optimal performance and reliability.

• Robotics projects using the Pololu Romi chassis.
• Educational and hobbyist robotics platforms.
• Autonomous vehicles and small-scale robotic systems.
• Projects requiring efficient motor control and power distribution.

• Motor Driver: Dual-channel motor driver for independent control of two DC motors.
• Input Voltage Range: 6 V to 10 V.
• Continuous Motor Current: Up to 1.2 A per channel.
• Peak Motor Current: 1.5 A per channel.
• Logic Voltage: 3.3 V or 5 V (selectable).
• Power Distribution: Provides regulated 5 V and unregulated battery voltage to peripherals.
• Dimensions: 2.1" × 2.3" (53 mm × 58 mm).
• Weight: 13 g.

The board features multiple connectors for motor control, power input, and peripheral connections. Below is a detailed description of the key pins and connectors:

1. Powering the Board:

   • Connect a 6 V to 10 V power source to the VIN and GND pins.
   • Ensure the power source can supply sufficient current for the motors and peripherals.

2. Connecting Motors:

   • Attach the first motor to the M1A and M1B terminals.
   • Attach the second motor to the M2A and M2B terminals.

3. Logic Voltage Selection:

   • Use the 3V3/5V_SEL jumper to select the appropriate logic voltage level (3.3 V or 5 V) based on your microcontroller.

4. Controlling the Motors:

   • Use the DIR1 and DIR2 pins to set the direction of Motor 1 and Motor 2, respectively.
   • Use the PWM1 and PWM2 pins to control the speed of Motor 1 and Motor 2 using PWM signals.

5. Powering Peripherals:

   • Use the 5V pin to power peripherals requiring regulated 5 V.
   • Use the VBAT pin to power peripherals requiring unregulated battery voltage.

• Ensure the total current draw of the motors and peripherals does not exceed the board's limits.
• Use appropriate heat dissipation methods if operating near the maximum current ratings.
• Verify the logic voltage level matches your microcontroller to avoid damage.
• Use decoupling capacitors on the power lines of sensitive peripherals to reduce noise.

Below is an example of how to control the motors using an Arduino UNO:

// Define motor control pins
const int DIR1 = 7;  // Direction pin for Motor 1
const int PWM1 = 6;  // PWM pin for Motor 1
const int DIR2 = 4;  // Direction pin for Motor 2
const int PWM2 = 5;  // PWM pin for Motor 2

void setup() {
  // Set motor control pins as outputs
  pinMode(DIR1, OUTPUT);
  pinMode(PWM1, OUTPUT);
  pinMode(DIR2, OUTPUT);
  pinMode(PWM2, OUTPUT);
}

void loop() {
  // Example: Drive Motor 1 forward at 50% speed
  digitalWrite(DIR1, HIGH);  // Set direction forward
  analogWrite(PWM1, 128);    // Set speed (0-255)

  // Example: Drive Motor 2 backward at 75% speed
  digitalWrite(DIR2, LOW);   // Set direction backward
  analogWrite(PWM2, 192);    // Set speed (0-255)

  delay(2000);  // Run motors for 2 seconds

  // Stop both motors
  analogWrite(PWM1, 0);
  analogWrite(PWM2, 0);

  delay(2000);  // Wait for 2 seconds
}

1. Motors Not Running:

   • Verify the power source is connected and providing sufficient voltage and current.
   • Check the motor connections to M1A, M1B, M2A, and M2B.
   • Ensure the DIR and PWM signals are correctly configured.

2. Overheating:

   • Ensure the motors are not drawing more current than the board's rated capacity.
   • Use heat sinks or active cooling if operating near the maximum current limits.

3. Peripheral Devices Not Powering On:

   • Check the VREG_EN pin to ensure the 5 V regulator is enabled.
   • Verify the peripherals are connected to the correct power pins (5V or VBAT).

4. Logic Voltage Mismatch:

   • Confirm the 3V3/5V_SEL jumper is set to match your microcontroller's logic voltage.

Q: Can I use this board with a 12 V power source?
A: No, the maximum input voltage is 10 V. Using a higher voltage may damage the board.

Q: What type of motors can I use with this board?
A: The board is designed for brushed DC motors with a nominal voltage between 6 V and 10 V.

Q: Can I control the motors without a microcontroller?
A: Yes, you can use external switches or a manual PWM generator, but a microcontroller provides more precise control.

Q: Is this board compatible with other chassis?
A: While it is optimized for the Romi chassis, it can be used with other platforms that meet the voltage and current requirements.