MicroPython MOTOR Library

Motor Library

motor

MicroPython Helper for controlling PWM based motors

  • Author(s): Scott Shawcroft, Jose D. Montoya

micropython_motor.motor.FAST_DECAY = 0

Recirculation current fast decay mode (coasting)

class micropython_motor.motor.MOTOR(positive_pwm, negative_pwm)[source]

DC motor driver. positive_pwm and negative_pwm can be swapped if the motor runs in the opposite direction from what was expected for “forwards”.

Motor controller recirculation current decay mode is selectable and defaults to motor.FAST_DECAY (coasting). motor.SLOW_DECAY is recommended to improve spin threshold, speed-to-throttle linearity, and PWM frequency sensitivity.

Decay mode settings only effect the operational performance of controller chips such as the DRV8833, DRV8871, and TB6612. Either decay mode setting is compatible with discrete h-bridge controller circuitry such as the L9110H and L293D; operational performance is not altered.

Parameters:
positive_pwm

The motor input that causes the motor to spin forwards when high and the other is low.

negative_pwm

The motor input that causes the motor to spin backwards when high and the other is low.

property decay_mode : int

Motor controller recirculation current decay mode. A value of motor.FAST_DECAY sets the motor controller to the default fast recirculation current decay mode (coasting); motor.SLOW_DECAY sets slow decay (braking) mode.

property throttle

Motor speed, ranging from -1.0 (full speed reverse) to 1.0 (full speed forward), or None (controller off). If None, both PWMs are turned full off. If 0.0, both PWMs are turned full on.

micropython_motor.motor.SLOW_DECAY = 1

Recirculation current slow decay mode (braking)

servo

MicroPython Helper for controlling PWM based servos

  • Author(s): Scott Shawcroft, Jose D. Montoya

class micropython_motor.servo.Servo(pwm_out, *, actuation_range: int = 180, min_pulse: int = 750, max_pulse: int = 2250)[source]

Control the position of a servo.

Parameters:
pwm_out

PWM output object.

actuation_range : int

The physical range of motion of the servo in degrees, for the given min_pulse and max_pulse values.

min_pulse : int

The minimum pulse width of the servo in microseconds.

max_pulse : int

The maximum pulse width of the servo in microseconds.

actuation_range is an exposed property and can be changed at any time:

servo = Servo(pwm)
servo.actuation_range = 135

The specified pulse width range of a servo has historically been 1000-2000us, for a 90 degree range of motion. But nearly all modern servos have a 170-180 degree range, and the pulse widths can go well out of the range to achieve this extended motion. The default values here of 750 and 2250 typically give 135 degrees of motion. You can set actuation_range to correspond to the actual range of motion you observe with your given min_pulse and max_pulse values.

Warning

You can extend the pulse width above and below these limits to get a wider range of movement. But if you go too low or too high, the servo mechanism may hit the end stops, buzz, and draw extra current as it stalls. Test carefully to find the safe minimum and maximum.

actuation_range

The physical range of motion of the servo in degrees.

Type:

float

property angle

The servo angle in degrees. Must be in the range 0 to actuation_range. Is None when servo is disabled.

stepper

MicroPython Helper for controlling stepper motors with microstepping support.

  • Author(s): Tony DiCola, Scott Shawcroft, Jose D. Montoya

class micropython_motor.stepper.StepperMotor(ain1, ain2, bin1, bin2, *, microsteps=16)[source]

A bipolar stepper motor or four coil unipolar motor. The use of microstepping requires pins that can output PWM. For non-microstepping, can set microsteps to None and use digital out pins.

Parameters:
ain1

machine.PWM or machine.Pin-compatible output connected to the driver for the first coil (unipolar) or first input to first coil (bipolar).

ain2

machine.PWM or machine.Pin-compatible output connected to the driver for the third coil (unipolar) or second input to first coil (bipolar).

bin1

machine.PWM or machine.Pin-compatible output connected to the driver for the second coil (unipolar) or second input to second coil (bipolar).

bin2

machine.PWM or machine.Pin-compatible output connected to the driver for the fourth coil (unipolar) or second input to second coil (bipolar).

microsteps : int

Number of microsteps between full steps. Must be at least 2 and even.

onestep(*, direction: int = FORWARD, style: int = SINGLE) → None[source]

Performs one step of a particular style. The actual rotation amount will vary by style. SINGLE and DOUBLE will normal cause a full step rotation. INTERLEAVE will normally do a half step rotation. MICROSTEP will perform the smallest configured step.

When step styles are mixed, subsequent SINGLE, DOUBLE or INTERLEAVE steps may be less than normal in order to align to the desired style’s pattern.

Parameters:
direction : int

Either FORWARD or BACKWARD

style : int

SINGLE, DOUBLE, INTERLEAVE

release() → None[source]

Releases all the coils so the motor can free spin, also won’t use any power