# VEX Motor Controller

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This article is only relevant for old VEX Cortex system, which is no longer competitive.
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![](https://phabricator.purduesigbots.com/file/data/etrlal4uipuwqzvaacuf/PHID-FILE-qlxacu4e34tv6ajfqnyf/vex_motor_controller.jpg)

A motor controller is not required for the [VEX Cortex](/vex-electronics/legacy/vex-cortex.md) ports 1 and 10.

The VEX Motor Controller performs the function of an ***H-Bridge***. Its FETs, or power output transistors, have a low enough ON resistance to not heat appreciably, even when controlling a [stalled](/electronics/general/stalling.md) motor. VEX Motor Controllers add an additional 24 inches of wire onto a motor, which can be a blessing to avoid a PWM extender or a curse when managing short wire runs.

VEX Motor Controllers are driven using a standard hobby servo control scheme, with a 1 ms pulse running full reverse, a 1.5 ms pulse stopping the motor, and a 2 ms pulse running full forward. A non-standard 200 us pulse will engage an active brake. These pulses typically appear on a 20 ms (50 Hz) duty cycle, but faster update rates up to 300 Hz may be possible with [PROS](/software/vex-programming-software/pros.md).

## Teams Contributed to this Article:

* [BLRS](https://purduesigbots.com/) (Purdue SIGBots)


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