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Motor Board API

The Motor Board can control up to two motors.

Accessing the Motor Board​

The Motor Board can be accessed by importing motors from sbot.

from sbot import motors

Powering Motors​

Motor power is controlled using Pulse-Width Modulation (PWM). You set the power with a fractional value between -1 and 1 inclusive, where 1 is maximum speed in one direction, -1 is maximum speed in the other direction and 0 causes the motor to brake.

motors.set_power(0, 1)
motors.set_power(1, -1)

These values can also be read back:

>>> motors.get_power(0)
1

>>> motors.get_power(1)
-1
warning

Setting a value outside of the range -1 to 1 will raise an exception and your code will crash.

warning

Sudden large changes in the motor speed setting (e.g. -1 to 0, 1 to -1 etc.) will likely trigger the over-current protection and your robot will shut down with a distinct beeping noise and/or a red light next to the power board output that is powering the motor board.

Special Values​

In addition to the numeric values, there are two special constants that can be used: BRAKE and COAST. In order to use these, they must be imported from the sbot module like so:

from sbot import BRAKE, COAST

BRAKE​

BRAKE will stop the motors from turning, and thus stop your robot as quick as possible.

info

BRAKE does the same as setting the power to 0.

from sbot import motors, BRAKE

motors.set_power(0, BRAKE)

COAST​

COAST will stop applying power to the motors. This will mean they continue moving under the momentum they had before.

from sbot import motors, COAST

motors.set_power(1, COAST)

Motor Status​

Several functions are provided to manage the Motor Board.

Get Motor Current​

You can get the current being drawn by either motor by passing a motor number to the get_motor_current function.

current = motors.get_motor_current(0)

The function returns the current being drawn in Amps as a float.

Check Fault Status​

For various reasons, such as a motor drawing too much current, the motor board can enter a 'fault' state. You can use the in_fault function to check for faults on either output.

m0_has_fault = motors.in_fault(0)

if m0_has_fault:
    print("Fault on motor 0 :(")

Reset Motor Board​

You can clear any faults by resetting the motor board.

motors.reset()