Adafruit Blinka supports PWMOut! This means you can easily pulse LEDs and control servos from your Raspberry Pi using any GPIO pin! This page will walk you through wiring up an LED and a servo, and provide an example for each.

Update Adafruit Blinka

Before getting started, make sure you're running the latest version of Adafruit Blinka. If you have not already installed it, run the following:

pip3 install adafruit-blinka

If you've previously installed it, you should run a pip3 update:

pip3 install --upgradeadafruit-blinka

Once you're certain that you are running the latest version of Adafruit Blinka, you can continue!

Supported Pins

PWMOut is supported on all GPIO pins on the Raspberry Pi! They are independent, and each can have a different frequency and duty cycle.

PWM - LEDs

This example will show you how to use PWM to pulse fade an LED.

First, wire up the LED to the Raspberry Pi.

Double-check you have the right wires connected to the right location, it can be tough to keep track of pins as there are forty of them!

No additional libraries are needed, so we can go straight on to the example code.

Run the following code:

# SPDX-FileCopyrightText: 2018 Kattni Rembor for Adafruit Industries## SPDX-License-Identifier: MITimport timeimport boardimport pwmioled = pwmio.PWMOut(board.D5, frequency=5000, duty_cycle=0)while True:    for i in range(100):        # PWM LED up and down        if i < 50:            led.duty_cycle = int(i * 2 * 65535 / 100)  # Up        else:            led.duty_cycle = 65535 - int((i - 50) * 2 * 65535 / 100)  # Down        time.sleep(0.01)

# SPDX-FileCopyrightText: 2018 Kattni Rembor for Adafruit Industries## SPDX-License-Identifier: MITimport timeimport boardimport pwmioled = pwmio.PWMOut(board.D5, frequency=5000, duty_cycle=0)while True:    for i in range(100):        # PWM LED up and down        if i < 50:            led.duty_cycle = int(i * 2 * 65535 / 100)  # Up        else:            led.duty_cycle = 65535 - int((i - 50) * 2 * 65535 / 100)  # Down        time.sleep(0.01)

Verify that the LED is pulsing. If not, check that it's wired to GPIO #5, the resistor is installed correctly, and you have a ground wire to the Raspberry Pi.

Type control-C to quit.

Servo Control

In order to use servos, we take advantage ofpulseio. You have two options. You can use the rawpulseio calls to set the frequency to 50 Hz and then set the pulse widths. Or, you can useadafruit_motor which manages servos for you quite nicely.

This section will cover both options.

Installadafruit_motor by runningpip3 install adafruit-circuitpython-motor

First, wire up a servo to your Raspberry Pi:

pulseio Servo Control

Run the following code:

# SPDX-FileCopyrightText: 2020 Kattni Rembor for Adafruit Industries## SPDX-License-Identifier: MITimport timeimport boardimport pwmio# Initialize PWM output for the servo (on pin D5):servo = pwmio.PWMOut(board.D5, frequency=50)# Create a function to simplify setting PWM duty cycle for the servo:def servo_duty_cycle(pulse_ms, frequency=50):    period_ms = 1.0 / frequency * 1000.0    duty_cycle = int(pulse_ms / (period_ms / 65535.0))    return duty_cycle# Main loop will run forever moving between 1.0 and 2.0 mS long pulses:while True:    servo.duty_cycle = servo_duty_cycle(1.0)    time.sleep(1.0)    servo.duty_cycle = servo_duty_cycle(2.0)    time.sleep(1.0)

# SPDX-FileCopyrightText: 2020 Kattni Rembor for Adafruit Industries## SPDX-License-Identifier: MITimport timeimport boardimport pwmio# Initialize PWM output for the servo (on pin D5):servo = pwmio.PWMOut(board.D5, frequency=50)# Create a function to simplify setting PWM duty cycle for the servo:def servo_duty_cycle(pulse_ms, frequency=50):    period_ms = 1.0 / frequency * 1000.0    duty_cycle = int(pulse_ms / (period_ms / 65535.0))    return duty_cycle# Main loop will run forever moving between 1.0 and 2.0 mS long pulses:while True:    servo.duty_cycle = servo_duty_cycle(1.0)    time.sleep(1.0)    servo.duty_cycle = servo_duty_cycle(2.0)    time.sleep(1.0)

The servo should sweep back and forth repeatedly. If it does not, verify your wiring matches the diagram above.

Type control-C to quit.

adafruit_motor Servo Control

Run the following code:

# SPDX-FileCopyrightText: 2018 Kattni Rembor for Adafruit Industries## SPDX-License-Identifier: MITimport timeimport boardimport pwmiofrom adafruit_motor import servo# create a PWMOut object on Pin D5.pwm = pwmio.PWMOut(board.D5, duty_cycle=2 ** 15,  frequency=50)# Create a servo object.servo = servo.Servo(pwm)while True:    for angle in range(0, 180, 5):  # 0 - 180 degrees, 5 degrees at a time.        servo.angle = angle        time.sleep(0.05)    for angle in range(180, 0, -5): # 180 - 0 degrees, 5 degrees at a time.        servo.angle = angle        time.sleep(0.05)

# SPDX-FileCopyrightText: 2018 Kattni Rembor for Adafruit Industries## SPDX-License-Identifier: MITimport timeimport boardimport pwmiofrom adafruit_motor import servo# create a PWMOut object on Pin D5.pwm = pwmio.PWMOut(board.D5, duty_cycle=2 ** 15,  frequency=50)# Create a servo object.servo = servo.Servo(pwm)while True:    for angle in range(0, 180, 5):  # 0 - 180 degrees, 5 degrees at a time.        servo.angle = angle        time.sleep(0.05)    for angle in range(180, 0, -5): # 180 - 0 degrees, 5 degrees at a time.        servo.angle = angle        time.sleep(0.05)

The servo should sweep back and forth in steps. If it does not, verify your wiring matches the diagram above.

Type control-C to quit.