adafruit_motor.motor

Simple control of a DC motor. DC motors have two wires and should not be connected directly to the PWM connections. Instead use intermediate circuitry to control a much stronger power source with the PWM. The Adafruit Stepper + DC Motor FeatherWing, Adafruit TB6612 1.2A DC/Stepper Motor Driver Breakout Board and Adafruit Motor/Stepper/Servo Shield for Arduino v2 Kit - v2.3 do this for popular form factors already.

Note

The TB6612 boards feature three inputs XIN1, XIN2 and PWMX. Since we PWM the INs directly its expected that the PWM pin is consistently high.

  • Author(s): Scott Shawcroft
class adafruit_motor.motor.DCMotor(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 (PWMOut) – The motor input that causes the motor to spin forwards when high and the other is low.
  • negative_pwm (PWMOut) – The motor input that causes the motor to spin backwards when high and the other is low.
decay_mode

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.

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.

adafruit_motor.motor.FAST_DECAY = 0

Recirculation current fast decay mode (coasting)

adafruit_motor.motor.SLOW_DECAY = 1

Recirculation current slow decay mode (braking)

adafruit_motor.servo

Servos are motor based actuators that incorporate a feedback loop into the design. These feedback loops enable pulse width modulated control to determine position or rotational speed.

  • Author(s): Scott Shawcroft
class adafruit_motor.servo.ContinuousServo(pwm_out, *, min_pulse=750, max_pulse=2250)[source]

Control a continuous rotation servo.

Parameters:
  • min_pulse (int) – The minimum pulse width of the servo in microseconds.
  • max_pulse (int) – The maximum pulse width of the servo in microseconds.
throttle

How much power is being delivered to the motor. Values range from -1.0 (full throttle reverse) to 1.0 (full throttle forwards.) 0 will stop the motor from spinning.

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

Control the position of a servo.

Parameters:
  • pwm_out (PWMOut) – 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.

angle

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

adafruit_motor.stepper

Stepper motors feature multiple wire coils that are used to rotate the magnets connected to the motor shaft in a precise way. Each increment of the motor is called a step. Stepper motors have a varying number of steps per rotation so check the motor’s documentation to determine exactly how precise each step is.

  • Author(s): Tony DiCola, Scott Shawcroft
adafruit_motor.stepper.BACKWARD = 2

“Step backward

adafruit_motor.stepper.DOUBLE = 2

Step so that each step only activates two coils to produce more torque.

adafruit_motor.stepper.FORWARD = 1

Step forward

adafruit_motor.stepper.INTERLEAVE = 3

Step half a step to alternate between single coil and double coil steps.

adafruit_motor.stepper.MICROSTEP = 4

Step a fraction of a step by partially activating two neighboring coils. Step size is determined by microsteps constructor argument.

adafruit_motor.stepper.SINGLE = 1

Step so that each step only activates a single coil

class adafruit_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.

PWM

Parameters:
  • ain1 (PWMOut) – pwmio.PWMOut-compatible output connected to the driver for the first coil (unipolar) or first input to first coil (bipolar).
  • ain2 (PWMOut) – pwmio.PWMOut-compatible output connected to the driver for the third coil (unipolar) or second input to first coil (bipolar).
  • bin1 (PWMOut) – pwmio.PWMOut-compatible output connected to the driver for the second coil (unipolar) or second input to second coil (bipolar).
  • bin2 (PWMOut) – pwmio.PWMOut-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.

Digital Out

Parameters:
onestep(*, direction=1, style=1)[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:
release()[source]

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