What a motor controller does#
The roboRIO can only output tiny signal-level power. A motor controller sits between the roboRIO and a motor, taking a low-power command and switching the full battery current (up to ~40A per branch) to drive the motor forward or backward at any speed. Modern controllers also do closed-loop control, current limiting, and report sensor data.
The major controllers#
Talon FX (CTR Electronics) - integrated directly into the Kraken X60, Kraken X44, and Falcon 500 brushless motors. Because the controller lives inside the motor, you run only power and CAN to one unit. It has a built-in encoder and the smart features of the Talon SRX and more. The newer Talon FXS drives both brushed and brushless motors.
SPARK MAX (REV Robotics) - a versatile controller for brushed and brushless motors, most commonly paired with the REV NEO and NEO 550. Controllable via PWM, CAN, or USB, with onboard closed-loop control using the NEO's integrated encoder. The SPARK Flex is its higher-power sibling, often paired with the NEO Vortex.
Talon SRX (CTR / VEX) - the original 'smart' brushed motor controller. CAN or PWM, with inputs for limit switches, encoders, and potentiometers. Common with CIM and 775pro motors.
Victor SPX (CTR / VEX) - a sealed, follower-friendly brushed controller. CAN or PWM, no sensor inputs of its own, often used as a 'follower' that mirrors a Talon.
Others - Venom (Playing With Fusion, integrated), Thrifty Nova (The Thrifty Bot), and Koors 40 (AndyMark) are also legal options.
Matching controller to motor#
Motor limits you should know (from REV's official motor comparison):
- Kraken X60: free speed ~6271 RPM, free current ~2.32A, stall current ~233A.
- Falcon 500 (v2): free speed ~6489 RPM, free current ~2.39A, stall current ~191A.
- NEO Vortex: free speed ~6784 RPM, free current ~3.62A, stall current ~211A.
- NEO (V1.1): free speed ~5820 RPM, stall current ~160A.
Notice the stall currents far exceed a 40A breaker. That is why current limiting in software is essential - it keeps the motor, wiring, and breaker happy during a stall.
Sources#
the part worth keeping
Key takeaways
- Motor controllers switch full battery current to motors based on low-power roboRIO commands.
- Talon FX is integrated into Kraken/Falcon motors; SPARK MAX/Flex pairs with REV NEO/Vortex.
- Talon SRX and Victor SPX drive brushed motors like the CIM and 775pro; Talon FXS handles brushed or brushless.
- Stall currents (Kraken ~233A, Falcon 500 ~191A, NEO Vortex ~211A) far exceed branch breakers, so software current limiting is essential.
Electrical & WiringMotor Controllers and the CAN Buslesson 1 of 3
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where this came from
Sources and corrections
This lesson is AI-assisted: drafted from primary sources, then reviewed and edited by hand. Errors still get through. When one is reported we fix it and write down what changed, in public, in the corrections log.
sources and further reading
- docs.revrobotics.comREV ION Brushless Motor Comparison
- docs.wpilib.orgWPILib Hardware Component Overview
clipped to this lesson
Articles that go further on this
The lesson gets you through the topic. These go wider on it, and they read in one sitting.
- 8 min readFRC Motors Compared: NEO vs Kraken X60 vs Falcon 500 vs NEO VortexCompare FRC brushless motors: REV NEO, NEO Vortex, Kraken X60, and Falcon 500. Exact specs, FOC explained, and which motor to pick for drivetrain vs mechanisms./blogread it
- 20 min readREV Robotics for FRC: NEO Motors, Spark MAX/Flex, PDH & MAXSwerveA practical guide to the REV Robotics FRC ecosystem: NEO, NEO Vortex and NEO 550 motors, Spark MAX and Spark Flex controllers, the PDH, and MAXSwerve./blogread it
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answer sheet
Lesson quiz
All 3 right completes the lesson. Miss one and only that question comes back, anything you already answered correctly stays banked.
0 of 3 answered
01What distinguishes the Falcon 500 and Kraken X60 from a motor like the REV NEO?
02Which statement about the REV SPARK MAX is correct?
03Why is software current limiting essential when running motors like the Kraken X60 or NEO Vortex?
Answer every question to submit.
All 35 lessons in Electrical & Wiringopenclose
01 / prerequisites
02 / control-system-components
03 / power-battery-breakers
04 / motor-controllers-can-bus
05 / connections-rules-troubleshooting
06 / worked-examples-mini-projects
- Not read yet:Mini-Project 1: A Single-Motor Test Stand from Battery to Spin
- Not read yet:Mini-Project 2: Current-Limited Drivetrain (CTRE and REV)
- Not read yet:Mini-Project 3: A Live Power-Monitoring Dashboard
- Not read yet:Mini-Project 4: A Switchable Channel for Lights and Vision
- Not read yet:Mini-Project 5: CAN Device Bring-Up with Tuner X and the Hardware Client
07 / common-mistakes-troubleshooting
08 / advanced-techniques-case-studies