Questions tagged [pwm]

Pulse-Width Modulation (PWM) is a technique used for controlling the power given to electrical devices. The average power supplied is controlled by rapidly turning the supply on and off. Questions here concern driving PWM outputs from the Raspberry Pi.

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How to create a data signal using pwm from a gpio output?

I'm a new member of the raspberry pi community and I have problems with starting my first project. I want to be able to create a data signal using pulse width modulation with the gpio headers. The ...
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Heatbed module control with Raspberry Pi 3+

I want to control a nichrome wire with the PWM signal from a Raspberry Pi. The MOSFET modules that can be found on the net for the combination with a Raspberry became much too hot. So I decided to try ...
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Triggering MAPIR camera with PWM via GPIO on RPi

I have similar setup as this post: PWM via GPIO to trigger a MAPIR Camera but a different camera: https://www.mapir.camera/collections/survey3/products/survey3w-camera-red-green-nir-rgn-ndvi. I am ...
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What options exist to manipulate voltage using a Raspberry Pi, above 5v?

I have a model train set which runs on 0-12v based on the position of a rotary encoder. I would like to have somewhat granular, digital control over the voltage on the track. So far, I'd implemented ...
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Increasing value as PushButton switch is keep on being pressed [closed]

For now I'm doing a project involving a Raspberry Pi and a push button. I managed to control LED with the push button using PWM where as we pressed the button, the duty cycle value increase. However, ...
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GPCLK vs PWM using micropython with Pico

I have a DC motor I can spin via ESC connected with a Raspberry Pi 4, but I want to use a Raspberry Pi Pico instead. Using GPIO4, that has the clock, I have this code that works for spinning the motor ...
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Can't generate PWM output on RP2040 other than square waves

I was playing with PWM on the RP2040. I can do square waves, but pretty much everything else does not work. I have recorded the PWM output with a sound card at 44100 Hz in order to verify it visually. ...
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Hardware PWM not working in Ubuntu 20.04

I'm running Ubuntu 20.04 on an RPI 3b. I need both Hardware PWM channels. I added the following line to /boot/config.txt and /boot/firmware/usercfg.txt: dtoverlay=pwm-2chan,pin=18,func=5,pin2=13,func2=...
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Pigpio Hardware PWM_unable to write frequency above 5Khz

I have been using the pigpio library as a modified spi interface to send and receive serial data. I use Chip Select, Clock, and Data Lines but i am using "bit-banging" for the timing between ...
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AttributeError: module 'RPi.GPIO' has no attribute 'ChangeDutyCycle'

Starting Day 2 troubleshooting this error. Code used to work on a previous rasp pi 4B but doesn't on a new one so I'm assuming I'm missing some breaking change. Problem: Using import RPi.GPIO as GPIO ...
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troubles with bcm2835 hardware PWM

I try to use hardware PWM on RPI 3b+ (Linux 11 bullseye) by using bcm2835.h (ver. 1.71) with small C code given below #include <bcm2835.h> #include <stdio.h> #include <stdlib.h> #...
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ERROR: PWM Generation using pigpio C library

I am working on the RPI-CM4 board with raspbian buster OS. I am trying to generate the 38KHz PWM wave using pigpio the library. My code is as follows. #include <pigpio.h> #include <unistd.h&...
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how to get more juice thru the Adafruit DC and Stepper Motor HAT?

We have a hat https://www.adafruit.com/product/4280 to turn i2c signals into pwm signals, into raw power for a DC motor. Let's start with this sample code: import time from adafruit_motorkit import ...
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Can i use a I2C PWM expander as a Digital output module?

i want to use a "IS31FL3731" I2C PWM expander to dim my LED Strip. This expander does have a lot of PWM outputs and i also need a lot of Digital outputs. So is it possible to use a few PWM ...
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Keeping a Python script for PWM running and just changing duty cycle

I am currently trying to connect a laser to my 3D printer and give a TTL signal manipulated by an M106 command. The "official" way didn't work out for me so right now I am trying to control ...
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Brushless Motor not spinning when controlling with PWM and ESC

I'm currently working on a drone which is controlled by a Raspberry Pi. I try to controll the motors by using PWM on the connected ESCs, which is described in many guides and forums. For that I use ...
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can dfrobot io expansion HAT read pwm input?

I bought this IO Expansion Hat from dfrobot that adds functions the rpi lacks, like analog pins and pwm output. Since this HAT has a STM32F030F4P6 with multiple 16bit timers, in theory I could use one ...
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PWM Set mode problem

As you know to work with Hardware PWM you must enable it at /boot/config.txt .I did that and i set GPIO 19 as PWM1 . it works well . but I notice that after the Raspberry Pi boots the GPIO 19 gives a ...
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How To make Raspberry Pi Hardware PWM off after startup

I am driving motor using ESC with Hardware PWM signal comes from Raspberry Pi ,I set the GPIO 19 (PIN 35) to be PWM1 , the problem is when the Raspberry Pi startup it gives output value to PWM1 (GPIO ...
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How to set raspberry pi gpio to low at boot (PWM pins)

I have project that works with raspberry pi 3 which control a motor speed through PWM0 pin (GPIO 19), the problem is that raspberry pi give high state after startup , which cause the spinning of the ...
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Using GPIO PWM with sysfs

I'm able to write to GPIO pins with sysfs with the standard commands like echo "1" > /sys/class/gpio/gpio6/value, but that only turns the pin on or off. I tried echo "0.5" > /...
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Can unstable PWM timing be corrected?

I would like to set the motor speed of a RPLidar A3 which requires a 25 kHz PWM. So I played around with the following: from RPi import GPIO GPIO.setmode(GPIO.BCM) GPIO.setup(12, GPIO.OUT) pwm = GPIO....
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38kHz, 50% duty cycle PWM output on GPIO

I'd like to generate 38kHz & 50% duty cycle PWM signals on multiple GPIO pins. Hence hardware PWM won't work for me. Does anyone have a chance to generate this signal by using python or node.js? ...
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1 answer
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PWM input to raspberry pi 4B

I want to read PWM output signal which I got from a sensor. Is there any way to give PWM signals as input to Raspberry pi 4B?
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1 answer
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PWM transducer won't update frequency

I'm creating a simple script that outputs a text input to morse with an LED and a transducer via the GPIO pins on a Raspberry Pi 4 Model B. I tried to add input functionality with buttons that can ...
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1 vote
1 answer
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What is a 'func' in PWM configuration?

To enable PWM on RPI, you need to modify /boot/config.txt. I found nice examples of what line I should add for various cases: https://github.com/dotnet/iot/blob/main/Documentation/raspi-pwm.md I do ...
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How do I change the PWM GPIO port in the sine_wave_pwm sample application of pico-playground?

This is the sample code in question: https://github.com/raspberrypi/pico-playground/tree/master/audio/sine_wave I cannot see where it has set it's PWM output pin. Inside "..pico-extras\src\...
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RaspBerry Pi pwmchip0 doesn't always work

I'm in a project currently using the RPi's pwmchip0 to implement Hardware PWM. I added the dtoverlay = pwm-2chan in the cofig.txt. Now when I follow that explanation https://jumpnowtek.com/rpi/Using-...
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Speed control for a generic 12v fan using Pi Zero

I am trying to speed control a generic 12V 2 pin computer case fan (80mm x 80mm x 15mm). I have purchased an Adafruit TB6612 1.2A DC/Stepper Motor Driver Breakout Board and a Raspberry Pi Zero W. I ...
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2 answers
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Issue with DMA+PWM based signal generator

I want to generate some signal on GPIO pin on Raspberry PI Zero W using DMA control blocks and PWM to pace data. However I faced with some problems while trying to generate signal at ~10-50kHz. When I ...
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1 answer
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GpioPinPwmOutput set pwm value with floating point

I have a raspberry pi 4 B and I want to control servo motor. I am using NetBeans IDE and Java programming language with pi4j library for raspberry. Also I have a servo motor that can rotate for 300 ...
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0 answers
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How to set PWM frequency below 1Hz on RPi?

does anybody know how to generate a PWM with less than 1Hz of frequency on Raspberry Pi? I'd like to generate a PWM with 0.1Hz if possible. Thanks in advance!
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2 votes
2 answers
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raspberry pi fan don't start to spin without hand help!

Raspberry Pi has recently added fan control feature in its raspi-config tool. This made me curious to add a fan to my RPI 4. I did it recently with a 680-ohm resistor, 2N2222 transistor, 1N4007 diode, ...
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1 answer
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Best GPIO API for high data rates and frequencies?

Using RPI3B+. I need to have 2 pins (a clock and data) to write data to shift registers on frequencies of 1,76 MHz or rate of 1,76 Mbps, and 1 pin(connected to GPIO 18) on 20 kHz. Tested RPi.GPIO.PWM ...
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Do GPIO 12 and GPIO 18 share the same frequency since they are the same channel?

Using RPI3B+. I already use GPIO 12 (the other PWM channel 0 pin) for a ledstrip. [Question: Can I use GPIO 18 on a different frequency, or do GPIO 12 and GPIO 18 share the same frequency when used as ...
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Controlling 4 servo motors through hardware PWM

I am working on a some time-critical system that will run image processing and controlling 4 SG90 servo motors. In short, I will do visual-servoing. Since I will do visual servoing, I don't want to ...
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LED strip works through Arduino PWM, but not Raspberry Pi PWM

I've been stuck on this for a while. I'm following a simple tutorial for RPi-controlled LEDs. From this, my LEDs do random stuff and don't light up correctly. I've been trying strandtest from this ...
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1 answer
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What is the relationship between angles and pulse length of servo motor?

I've been working on a project where I've to drive the servo motors. I am using Raspberry Pi 3B+ model and Adafruit PCA9685 to drive the servos. For that I need to find which angle is at what pulse ...
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1 vote
1 answer
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Controlling WS2812 with a non-PWM pin

I was looking for a way to control WS2812 led without PWM pin (specifically I would use pin 4 (1-WIRE pin) to control WS2812). Is it possible? Thanks
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How to make/get a proportional flow control valve [closed]

I want to use hydraulic flow to proportionally vary the resistance of a rpi controlled exercise machine. The victim would rotate a positive displacement pump where the inlet and outlet ports are ...
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2 answers
128 views

pigpio scrambles hardware PWM signal

I'm using a dedicated library to run a ws2812 led strip. As far as I understand, this library sends a signal using the hardware PWM, via GPIO pin 18. This works fine and the led strip shows the colors ...
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Sending Square Waves to more than one gpio pin with pgpio

I've been searching around for a few days and couldn't find a solution to this problem. I'm using the pgpio library that is native to the RPi4 and been looking all over their website: http://abyz.me....
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3 answers
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How to use Rpi python GPIO pins in PWM output mode to create PWM signals?

I was trying to understand PWM when I ran across this example: import RPi.GPIO as GPIO GPIO.setmode(GPIO.BOARD) GPIO.setup(12, GPIO.OUT) p = GPIO.PWM(12, 0.5) p.start(1) input('Press return to stop:')...
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RPi PWM issues - (re)start results in oscillating pin

I'm building a sauna controlling mechanism, controlled by the Pi, using PWM and solid-state relays. Works fine, but after a while, the PWM breaks down. At this moment, when I run the program and the ...
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Turn on an LED with dimming and stay on

I want to start the LED gradually with dimming by using PWM. And then once at a ChangeDutyCycle(100) I want it to remain on GPIO.output(led, GPIO.HIGH). import RPi.GPIO as GPIO import time led = 17 ...
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How to create unfazed pwm signals?

I have two pins with the same frequency (10Hz) and same duty cycle (50%) assigned to two different leds. How can I make the two leds blink alternatively? How can I put a delay of 50% in one of the ...
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1 answer
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Raspberry Pi Software Driven servo control with PWM using C and Wiring Pi LIbrary

I'm trying to get my raspi zero to move an SG90 PWM driven servo. I have achieved this with python already using the gpiozero library, so I know my hardware works but I am trying to do it with C using ...
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How to control a Servo via libgpiod on a raspberry PI

I am trying to control a Servo in c ++ using the libgpiod library. My problem is in defining the 50Hz pwm pulse on the pin that the servo is connected to. The servo signal cable is connected to pin 33 ...
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3 votes
2 answers
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PWM frequency/profile for "official" pi fan?

I have a pi4 with the "official" fan case and I would like to write my own fan control code. I have looked online for a datasheet for the fan but haven't found it yet. I see on the case fan ...
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Reading current PWM output configuration

I use gpio #32 (wPi #26) as PWM output to control the speed of a fan based on temperature. The job starts at system startup with a dedicated account. I would like to display the current value that is ...
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