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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114 views

Issues with Throttle Control on ESC with RPi 3B+

I am using the 30A BLDC ESC to control a brushless motor from my Raspberry Pi 3 B+. The documentation for the ESC can be found here: ESC pdf I seem to have successfully calibrated the ESC, but after ...
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201 views

Using pigpio and hardware PWM simultaneously

I am using pigpio to read 4 inputs. Everything works fine. And the entire process is a bit long and memory consuming. I also have to use one PWM output. I am planning to use the hardware PWM (pin 12 ...
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1answer
154 views

PWM not reaching desired frequency after checking on oscilloscope

I am attempting to setup a PWM signal on Pin 12 (GPIO #18) using a Raspberry Pi 3. I am capable of sending a PWM signal, however it is quite off from the target frequency. I have an o-scope that I ...
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279 views

pigpio hardware PWM for servos

My goal is to build a pan/tilt system. this works fine: import pigpio pi = pigpio.pi() pi.set_servo_pulsewidth(13,1055) 2 questions: is pi.set_servo_pulsewidth using hardware PWM (I prefer HW PWM) ...
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3answers
229 views

Can I reliably control four ESC with a servo driver board?

Im currently looking into building a quadcopter from scratch. The Raspberry Pi only has two PWM pins though, which isn't enough. And software PWM isn't great either, because you can't control a motor ...
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108 views

High-precision time-varying PWM outputs on R Pi

I'e seen a lot of examples of simple PWM on the Pi where relatively high-precision PWM signals at a fixed duty cycle can be generated using WiringPi or pigpio in hardware PWM mode. I have tried ...
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23 views

pwmWrite() dosen't run

else if(strcmp(hyp,"MEDIUM") == 0) { system("espeak 'medium'"); printf("%s\n", hyp); digitalWrite(LIGHT1, HIGH); pwmWrite (PWM_pin1, 524) ; } i try to control ...
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281 views

pigpio: Read PWM from RCcontroller then send to ESC via GPIO

Im trying to learn Python by combining my interest in designing an AWD radio controlled car (3D printed, Im decent with Fusion 360 too) with some smarts from Pi/Python to allow things like software ...
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1answer
182 views

Servo motor keep shaking while using software PWM to drive

Greet everyone, I am using JavaScript with pigpio to develop my learning project. How come my servo motor keeps shaking when I drive it by program PWM? codes are posted as follow: var servo1GPIO ...
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96 views

Is it possible to control servos in both directions on the RPi?

I have been working on controlling servos in one direction with PWM control via GPIO ports on my RPi 3. I've worked with motor controllers that use PWM before and it seems that I should be able to ...
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47 views

pigpio servo, stop command not reliable

import pigpio import math import RPi.GPIO as GPIO from gpiozero import Button import time GPIO_SERVO_PIN = 27 limit = 17 switch = Button(limit) GPIO.setmode(GPIO.BCM) GPIO.setup(17, GPIO.IN, ...
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57 views

Interrupt Servo once movement has initiated

I'm new to python and RPis. I'm building my own robot to learn. I manage to control my little robot and move it around, as well as moving the pan camera with my keyboard. While I was searching for a ...
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1answer
165 views

Control PWM duration with python

I need to control the PWM module on the raspberry pi. I’m now familiar with pigpio, and with hardware_PWM. However, I did not find anywhere where I can control the total duration of the PWM. Example: ...
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1answer
3k views

What is the relationship between angle and servo motor duty cycle? How do I implement this?

I am unsure of the relationship between duty cycle and angle. I see lots of tutorials online with many different equations to calculate duty cycle for a given angle. I have a 50Hz servo motor that ...
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236 views

Pigpio Hardware PWM callback is slow

I am trying to drive a servo motor with Raspberry pi. I have selected pigpio library to access GPIO. I need to send a specific number of pulses with a given frequency. But when I callback a function ...
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1answer
583 views

is it possible to get 12 bit(4096) resolution output from pi hardware pwm pin?

I want to produce 12 bit resolution from Pi hardware pwm pin for my project. Please help me to go in right way as I am new to both Python and Pi. import time import pigpio as pi import RPi.GPIO as g ...
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1answer
2k views

What is the proper calculation of duty cycle range for the sg90 servo?

In all specs of this servo that I can find there is a range of 1000-2000ms of duty cycle, for 50 Hz frequency, for the full range of motion. For example: http://m.zonesutech.com/Content/upload/...
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79 views

Voltage amplifier for pwm output

I am trying to use the PCA9685 to power a regular desktop pc cooler fan, the idea being to later be able to freely adjust the fan speed depending on the pwm set in the pwm driver.(similar to this) On ...
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685 views

Sine Triangular PWM using Raspberry Pi 4

I am new to Raspberry pi. I want to make sine triangular PWM which will control the H-bridge of the inverter. I generate sine wave (50 Hz)and triangular wave (1500 Hz) using python language and ...
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261 views

How do I setup the clock form pwm device tree overlay

I am trying to use pwm on GPIO pin 40 but I have been unsuccessful so far. I am using pwm as device tree overlay in my config.txt dtoverlay=pwm,pin=40 After that I tried performing the below actions ...
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1answer
152 views

How can you use pigpio to set a specific position for a continuous rotation servo?

Running my code with a normal 180 degree servo will move it to a user-specified angle and then hold it there. But when using a continuous rotation servo, it keeps rotating constantly for 500 <= ...
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3answers
177 views

Servo motor behaves odd

hello I Connected a servo motor to my Raspberry pi Zero W and used the example from raspberrypi.org: granpa scarer: Grandpa Scarer and the servo worked however after changing the value for: p....
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1answer
319 views

Using pigpios waves and audio output

I am using a Raspberry Pi 3 B+. I want to play audio through the 3.5mm jack and use PWM at the same time or successively to simulate a IR-Remote. I know that you can't use the hardware PWM while ...
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0answers
77 views

PWM on pump not working as expected

I am attempting to run a PWM on a pump using rpi.GPIO using the following code: def run_PWM_on_pump(): gpio.setmode(gpio.BOARD) gpio.setup(8, gpio.OUT) p = gpio.PWM(8, 0.5) #also works at ...
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1answer
782 views

How can Rpi4B python UART talk to XY PWM Signal Generators?

Currently I am trying to automate a coil winding machine using stepper motors. I wrote a Python code to send frequencies to the stepper motors. But for some reason, the frequencies produced by ...
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1answer
291 views

How to use Rpi GPIO to PWM adjust IR LEDs brightness?

I'm using this circuit for my project, which I referred from https://www.sparkfun.com/news/1396. I don't really understand how current works in GPIO pins, so the question is: instead of connecting ...
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1answer
1k views

How can I power a IR LED ring using GPIO port?

Okay so, I'm currently working on a final year project about vein visualization with Raspberry Pi 3 Model B+ and a NoIR camera V2. An infrared light source is required to capture clear vein image. I'...
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2answers
1k views

AC mains dimmer dimming 7W LED lamp problem (RpiZero + MPDM V4.1)

I'm trying to dim a 7W LED with a Raspberry Pi Zero for home automation. However it doesn't work as expected. I followed this tutorial : https://www.youtube.com/watch?v=wqY4-gHqvZI . I have the exact ...
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1answer
75 views

I2S 3W Class D Amplifier and 2.2“ SPI-Display (ILI9341) - GPIO 18 Problem

I want to connect the Adafruit I2S 3W Class D Amplifier Breakout Board and an 2.2" TFT Display (ILI9341) to a Raspberry Pi Zero. However, it seems that by default both components use the GPIO 18 (the ...
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1answer
517 views

Setting up the second PWM channel from kernel module not working on RPI 3 model B+

I'm trying to set up both PWM channels (PMW0 and PMW1) on my Raspberry Pi 3 Model B+ from my kernel module. I've successfully set up channel 0 with the desired frequency and variable duty cycle and I'...
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1answer
189 views

What is the frequency and cycle length of the pigpio library?

I've got a raspi 3b with an esc and a brushless motor attached. I can run the motor using pigpio the following commands: # First start the pigpio daemon sudo pigpiod # calibrate the esc pigs s 12 ...
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2answers
1k views

How to use Rpi python to read/write/convert, to/from Arduino PPM and PWM servo control signals?

I want to create a python equivalent of the RCPulseIn library for arduino that does all the same functions of the library. I have written up a code that has lots of errors, but has sort of a framework ...
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1answer
264 views

PIGPIO problem with delay on scripts

I am trying to run an old Raspberry Pi 2011.12 as a server to control a RGB LED strip. To this I am using PIGPIO since this is the best solution (RPi.GPIO is software based, which creates flickering). ...
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1answer
3k views

PWM on 5V GPIO pin

I have a 12V Noctua industrial fan (it's for a project, the amount of airflow is needed). The fan doesn't turn on by itself (with only 12V and GND connected), but it does turn on when I connect GPIO ...
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1answer
144 views

GPIO PWM. ESCs still run different after calibration

I’m putting a quadcopter together. I’m using a python script to calibrate the ESCs... they beep like a blinking led when I give them power. Then I run the calibrate script and they give me the proper ...
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0answers
71 views

Adafruit ServoHat importing PWM object

I am following the Adafruit page regarding the ServoHat for the Raspberry Pi. I am unclear what module to import to get the PWM class. This is the page about using the PWM class: https://learn....
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1answer
1k views

No module named 'adafruit_circuitpython_servokit' [closed]

I have a Adafruit PWM hat and I am trying to run play around with some servos. However, when I run this line: from adafruit_servokit import ServoKit It returns: No module named '...
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1answer
152 views

How to use at the same time 2 hardware pwm in wiringpi

I need help to configure 2 hardware PWM channels. I am developing device, and sometimes I will need active 2 PWM channels with different frequencies (frequencies is low: 410 and 580 Hz).I'm writing ...
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1answer
139 views

Piscope resolution

I generate a carrier frequency at 38KHz and I see the output LIVE in the piscope, but the "pulse widths" are not perfect ... the pulses are more or less wide when they must all have the same width. It ...
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1answer
101 views

PWM in raspberry with L293D

maybe this ask is repeated but i need solve this special situation, i have an arm robot with 3 Freedon deegre, i want to control position of each motor with a raspberry pi 2 and L293D like a motor ...
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0answers
67 views

Waveform not cancelling out hardware PWM

I've run into problems using pigpio's wave generator in combination with hardware PWM. Currently I'm working on a motion control with acceleration/sustain/deceleration phases. The phases are saved ...
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0answers
2k views

A PWM object already exists for this GPIO channel

I have a bit of a dilemma. I am currently using BCM GPIO 14, 15 and 18 to control an RGB status LED using PWM. I have configured my raspberry pi 3 to pull down pin 14 (red) on boot, to indicate the ...
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1answer
56 views

connect 4 measuring devices output to a raspberry and set a Pin high if value exceed a particular value

I have a special measuring system. Each measuring unit gives PWM output (total 4 outputs). Maximum frequency will be 10Khz (for each output). I wanna measure the frequency of each PWM evey second ...
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2answers
2k views

How can Rpi move a Servo motor using a GPIO pin in PWM mode?

iam new to raspberry pi and i got an error while a running servo motor in my object detection script i need to run the servo whenever my if condition is true so the same pin run multiple times if ...
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1answer
286 views

Sg 5010 servo 360 degree modification not working [closed]

As per the video tutorials out there, I opened the motor, took out the potentiometer and measured its resistance at max. Its a b5k pot so it measured 5kohm I put 2.5k ohm from each pin (s and -) and ...
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1answer
441 views

pwmWrite() does not change dutycycle immediately

I'm using wiringPi for PWM on BCM18. I tried to use this to generate a STROBE-equivalent signal to turn ON the LED for the Camera Capture. My intention is to synchronize the LED-ON to shutter opening (...
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1answer
167 views

PWM with pigpio does not trigger alert function regularly

I combine C examples of pigpio for gpioSetAlertFunc and gpioWaveTxSend working with the same pin. My PWM has several pulses, so I expect alert function to print out a message for me several times. ...
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1answer
938 views

sudo with WS2812 and Raspberry Pi

I'm trying to use the Neopixel Adafruit library with the WS2812 strip. Everything works great however there is something that I have not been able to do. I'm working on a project that requires ...
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2answers
414 views

Turn a Raspberry Pi into a voltage tester

I would like to create a voltage tester like the one described in this video, using 555 ic, and then connect it to Raspberry Pi, in order to log the frequency a 220V waterpump is switched on. My ...
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1answer
558 views

Python RPIO.ChangeDutyCycle() Equivalent in WiringPi (C)

I'm currently developing an application with the WiringPi library. I have implemented a prototype in Python, and I'm currently trying to reproduce the same behaviour in C++. However, I ran into some ...