SMD Red
The Brushed DC Motor Driver
Last updated
The Brushed DC Motor Driver
Last updated
The Acrome SMD Red is engineered to deliver revolutionary solutions in robotics and motion systems involving brushed DC motors. Designed with a modular, plug-and-play approach, SMD Red enables users—from makers to educators—to unleash their creativity and focus entirely on their motion-based projects.
At its core, SMD Red’s strength lies in its compatibility with a wide ecosystem of Acrome Smart Motion Devices (SMD modules), enabling seamless integration for a wide range of robotic and automation applications. Whether you're building a basic mobile platform or developing a more complex, sensor-driven system, SMD Red adapts to your needs with ease and efficiency.
Seamless Integration – Fully plug-and-play with all Acrome Smart Motion Device (SMD) add-on modules.
Scalable Networking – Supports daisy-chaining via RJ-45 for synchronized multi-device communication.
Intelligent PID Autotuner – Built-in Cohen-Coon-based tuning engine ensures optimal motor control under various load conditions.
Modular I/O Architecture – Smart RJ-11 ports for effortless sensor and actuator integration.
Integrated Power Distribution – On-board regulation with pass-through power terminals for clean system expansion.
Cross-Platform Development – Compatible with Python SDK, Arduino, Blockly UI, and command-line interfaces.
Modular & Synchronized Design – Architected for scalable, distributed robotics applications.
Automated Precision Tuning – PID autotune delivers fast, adaptive control without manual tweaking.
Simplified Cabling – Dual daisy-chaining (data + power) minimizes wire clutter and setup time.
Full-Stack Software Support – From beginner Blockly users to advanced Python and embedded developers.
The integrated autotuning engine calculates optimal P, I, D parameters using the Cohen-Coon method, offering:
Improved control performance under varying loads
Faster response and higher accuracy
Automatic tuning within ~30 seconds
Each SMD Red can connect multiple modules via RJ-11, while the RJ-45 bus allows multiple SMD Reds to operate synchronously in networked robotic systems. The RS-485-based protocol ensures high-speed, reliable communication.
Easily power multiple SMD Reds in a chain with daisy-chain-compatible power terminals, reducing wiring complexity and enhancing system stability.
Precision Motor Control with Real-Time Insights
SMD Red delivers an advanced control architecture that combines fine-grained motor configuration with live system diagnostics — all accessible through intuitive register settings. Whether you're building a robotic arm, a mobile platform, or a smart actuator system, SMD Red empowers you with full authority over motion behavior.
Monitor your motor’s status in real time with read-only feedback registers:
Present Position: Current encoder count (absolute tick value)
Present Velocity: Instantaneous speed (ticks per 100 ms)
Present Torque: Actual current draw in mA (indicates load or resistance)
This real-time visibility is critical for diagnostics, closed-loop feedback, data logging, or adaptive control strategies.
All registers are accessible via the Acrome Python SDK, Arduino libraries, or custom serial protocols. This flexibility makes it easy to build anything from beginner experiments to industrial-grade motion systems.
Configure how the motor responds using the Operation Mode register:
0x00 – Position Control Drives the motor to a precise target position. Ideal for robotic joints, linear axes, and precision mechanisms.
0x01 – Velocity Control Maintains a constant rotational speed. Suitable for wheels, conveyors, and continuous motion systems.
0x02 – Torque Control
Regulates motor torque by controlling current output.
Useful for force-sensitive applications like grippers, presses, or tensioning systems.
To start or stop the motor, toggle the Torque Enable register:
1 → Motor output enabled
0 → Motor safely disabled (required before modifying critical parameters)
0x03 – PWM Mode Directly controls the motor output using a user-defined PWM duty cycle. This mode bypasses closed-loop control and sends raw PWM signals to the motor, giving full manual control over power delivery. Ideal for advanced users who require custom control behavior, signal testing, or integration with external controllers.
Manually tuning a PID controller can be tedious and error-prone. SMD Red simplifies this with an integrated Autotuner.
By setting the Autotuner Enable register to 1, the system automatically performs PID calibration using the Cohen-Coon method — a proven control algorithm.
- Completion in ~30 seconds
- Optimized P, I, D values for your specific load and application
- Works for position and velocity modes
This enables seamless adaptation for changing dynamics without manual calculation or trial-and-error.
Each control mode accepts a setpoint:
Position Setpoint: Encoder tick value
Velocity Setpoint: Speed (ticks per 100 ms)
Torque Setpoint: Desired current (mA)
Define limit thresholds to prevent unsafe behavior:
Current Limit: Max current draw (0–65535 mA) to avoid overheating or overload
Velocity Limit: Max speed limit (ticks/100 ms) for safe operation
Position Limits: Define physical range boundaries for travel
These constraints ensure safe, reliable operation — especially in high-risk or autonomous systems.
Ambient Light Sensor Module
Detects surrounding light intensity
Button Module
Simple digital input trigger
Buzzer Module
Emits audio signals for alerts or feedback
IMU Module
Measures orientation and acceleration (gyroscope + accel)
Joystick Module
Manual directional control input
Potentiometer Module
Analog input for tuning or manual adjustment
Reflectance Sensor Module
Ideal for line-following robot applications
RGB LED Module
Visual output for feedback and signaling
Servo Module
Controls servo motors for angle-based motion
Ultrasonic Distance Sensor
Measures distance for obstacle detection and avoidance
SMD RED has two power ports, two RJ-45 ports for the connection between SMD REDs, one I2C port for sensor connection and an actuator port. Ports are shown in the image below, a detailed map can be seen atDetailed Port Map of SMD Red.
🟡 Yellow
No EEPROM Save Detected
Stays on until user performs EEPROM save. Also appears after Factory Reset. If still lit after saving, EEPROM may have issues. Not considered an error by itself.
⚪ White
IDLE / Firmware Status
Solid: IDLE mode. Blinking fast (every 50ms): No valid firmware or hardware mismatch. Blinking slow (every 150ms): Scanning modules.
🟢 Green
Ready / Motor Active
Indicates the motor driver is active and ready to drive. Should be on when the motor is running.
🔵 Blue
Autotuning Active
Blinks during PID tuning. Torque must be enabled. It is normal to see blue and green together during this state.
🔴 Red
Overcurrent / Current Limit
Turns on when the motor draws excessive current or exceeds the defined current limit. Can resume by toggling torque off and on.
🟣 Purple
Communication Issue
Appears when communication fails between modules or host device.
🟦 Cyan
User Indicator
Blinks when userIndicator is triggered by user code. Not shown unless explicitly activated.
SMD Red is compatible with multiple software environments:
SMD Blockly – Visual programming environment for beginners
Python SDK – Advanced scripting for real-time control and logic
Flutter Mobile App – Wireless control via smartphone or tablet
CLI Access – Direct low-level command-line communication
Two-wheel differential drive robots with encoder feedback
PID-based motion control experiments
Pan-tilt camera or sensor platforms
Sensor-guided obstacle avoidance
Mobile robot with joystick input and RGB LED feedback
Here is a demonstration of daisy-chain and cable management used for "Synchronizing Linear Motors" application:
SMD Red is more than just a motor controller—it's a scalable, modular, and smart development platform for anyone working in robotics, automation, or STEM education. By combining hardware simplicity with software versatility, SMD Red raises the bar for motion control solutions.
From your first mobile robot to an advanced synchronized system, SMD Red is built to grow with your ideas.
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