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I'm working on a project that needs three (or more) PWM pins to work. But unlike Arduino, the Raspberry PI B+ has just one PWM pin. I've searched for solutions and I found that I can use the WiringPi to emulate PWM using software. Is this the best solution? Anybody has a better one?

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  • What specifically are the three PWM pins for?
    – goldilocks
    Jan 18, 2016 at 12:53
  • Acceleration control and Servo.
    – bodruk
    Jan 18, 2016 at 12:54
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    There's also pigpio that can do software PWM, see raspberrypi.stackexchange.com/questions/41140/… Sorry, Joan, I didn't see your answer while posting this comment. Anyway the linked Q&A is related - to whom it may concern.
    – Ghanima
    Jan 18, 2016 at 15:04

2 Answers 2

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The Raspberry Pi B+ has two accessible dedicated hardware PWM channels.

Hardware timed PWM is available on all the accessible GPIO.

See my pigpio library.

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  • Is this a good solution for servos and acceleration control?
    – bodruk
    Jan 18, 2016 at 13:13
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    Yes to servos. What do you mean by acceleration control? If you mean varying a DC motor speed then yes.
    – joan
    Jan 18, 2016 at 13:21
  • Is this lib similar to WiringPi?
    – bodruk
    Jan 18, 2016 at 13:41
  • Not really. The library is written in C. That's the only thing in common.
    – joan
    Jan 18, 2016 at 14:23
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Studying the WiringPI library I found that I can easily handle the PWN on any pin:

# GPIO port numbers  
import wiringpi2 as wiringpi  
wiringpi.wiringPiSetupGpio()  
wiringpi.pinMode(25, 0) # sets GPIO 25 to input  
wiringpi.pinMode(24, 1) # sets GPIO 24 to output  
wiringpi.pinMode(18, 2) # sets GPIO 18 to PWM mode 
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  • I'm not sure if wiringPi can drive both the dedicated PWM channels. wiringPi PWM on arbitary GPIO will be software timed, servos in particular may have problems with jitter.
    – joan
    Jan 19, 2016 at 12:40

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