SPARKmini Motor Controller
The SPARKmini Motor Controller (REV-31-1230) is an inexpensive in-line brushed DC motor controller designed to give FIRST® Tech Challenge teams more bang for their buck. It offers the same performance characteristics as the REV Control Hub (REV-31-1595) or Expansion Hub (REV-31-1153) motor ports in a small 60mm x 22mm footprint. Now FTC teams can add a SPARKmini Motor Controller to utilize more than four DC motors from a single Hub in a space-efficient package.
Connect the power wire to a free XT30 port on the REV Control Hub , REV Expansion Hub (REV-31-1153), or through an XT30 Power Distribution Block (REV-31-1293) that is connected to a free Control/Expansion Hub XT30 port. Connect the control wire to an open servo port on the hub and the motor wire to a JST-VH port on a motor, like the REV HD Hex Motor (REV-41-1301) or the REV Core Hex Motor (REV-41-1300).
A motor’s speed is controlled by varying the voltage that is applied to it. The SPARKmini’s output voltage can be controlled by sending it an extended-range servo-PWM pulse. The extended 500µs to 2500µs servo-pulse corresponds to full-reverse and full-forward rotation with 1500µs as the neutral position (no rotation). The pulses are proportionally related to the motor output duty cycle, therefore variable speed can be achieved with pulses in between the extremes. The following table describes the pulse ranges in more detail.
Table - Control Signal Pulse Ranges
When the SPARKmini is receiving a neutral command it will not provide any power to the attached motor. There are two options for how the SPARKmini handles this zero-power state:
Brake - Motor terminals are shorted to each other to dissipate electrical energy, effectively braking the motor. Coast - Motor terminals are disconnected, allowing the motor to spin down at its own rate.
The zero-power behavior can be selected via a switch located towards the center of the SPARKmini housing, shown in Figure 2. Each mode can be selected by sliding the switch to either the Brake (B) or Coast (C) positions.
The SPARKmini will indicate whether it is in Brake or Coast mode via the Status LED, located in the center of the housing, whenever it is outputting zero-power. Solid or flashing blue indicates Brake Mode while solid or flashing yellow indicates Coast Mode. See the LED Status Codes section for more details.