pwm with wiringPi Python?

I'm trying to get pwm working by "dimming" an LED up and down:

Code: Select all

def pwm_dimm(io):
    pin = 1 # only supported on this pin
    io.pinMode(pin,io.OUTPUT)

    while 1:
        print "Up"
        for i in range(0,1024,16):
            io.pwmWrite(pin, i)
            time.sleep(DELAY)
        print "Down"
        for i in range(1024,0,-16):
            io.pwmWrite(pin, i)
            time.sleep(DELAY)


This does very much not work- the LED just stays on. The pin is correctly wired as using digitalWrite I can flash the LED.

Any ideas?

I'm trying to get pwm working by "dimming" an LED up and down:

Code: Select all

def pwm_dimm(io):
    pin = 1 # only supported on this pin
    io.pinMode(pin,io.OUTPUT)

    while 1:
        print "Up"
        for i in range(0,1024,16):
            io.pwmWrite(pin, i)
            time.sleep(DELAY)
        print "Down"
        for i in range(1024,0,-16):
            io.pwmWrite(pin, i)
            time.sleep(DELAY)


This does very much not work- the LED just stays on. The pin is correctly wired as using digitalWrite I can flash the LED.

Any ideas?

I'm not a Python programmer, but I did write wiringPi

Before you use the single PWM pin on your Pi, you need to set it into PWM mode - and I don't see that in your code above - I do see you setting it to an output though. This won't work. Do whatever you need to do via the Python wrappers to set it into PWM mode. Maybe:

io.pinMode(pin,io.PWM)

?

You also need to call some sort of wiringPi setup code too, but maybe you're doing this elsewhere.

And remember that there are 2 ways to initialise wiringPi - the wiring native mode uses pin 1 (which you're using here), or the hardware bcm-gpio mode when it would be pin 18.

(and I wish I've never bothered listening to people who wanted the bcm_pin numbering mode and stuck to wiringPi numbers, but that's another story!)

-Gordon

Hi Gordon,
This is excellent, thanks a lot! I did do the setup but forgot PWM mode.
Thanks for your excellent piece of software!
Kind regards, Andreas

hi..

can you write down exact program to run this project...

because i can understand..
i want run this project...

thank you

Sure, check this out:

Code: Select all

import wiringpi, time

DELAY_PWM = 0.005

def reset_pins(io):
    pins = [0,1,2,3,4,5,6,7, ]
    for pin in pins:
   io.pinMode(pin,io.OUTPUT)
   io.digitalWrite(pin, io.LOW)

def pwm_dimm(io):
    STEP = 8
    pin = 1 # only supported on this pin
    io.pinMode(pin,io.PWM_OUTPUT)

    while 1:
   #print "Up"
   for i in range(0,1024,STEP):
       io.pwmWrite(pin, i)
       time.sleep(DELAY_PWM)
   #print "Down"
   for i in range(1023,-1,-STEP):
       io.pwmWrite(pin, i)
       time.sleep(DELAY_PWM)


# direct
#io = wiringpi.GPIO(wiringpi.GPIO.WPI_MODE_SYS)
io = wiringpi.GPIO(wiringpi.GPIO.WPI_MODE_PINS)

try:
    reset_pins(io)   
    pwm_dimm(io)

except (KeyboardInterrupt, SystemExit):
    reset_pins(io)


thanks,


and which pin is used here?

Well- the code says pin=1, right? Check the WiringPi docs which one that is.

Well- the code says pin=1, right? Check the WiringPi docs which one that is.

wiringPi pin 1 is the chip's GPIO pin 18.

(that's the only hardware PWM pin avalable - easilly)

My diagram is here:

https://projects.drogon.net/raspberry-pi/wiringpi/pins/

-Gordon

thanks
but still running error..

please list all step ,not about program but how can i excess it in terminal window,
from 1sr step to last

i am new for this wiringpi so, when i have run this code it says that wiringPi modual nit found

so what can i do??

i am new for this wiringpi so, when i have run this code it says that wiringPi modual nit found

so what can i do??

I'm not sure - this is really a thread about with Python wrappers for wiringPi - which I didn't create (I just did the wiringPi part - which is in C).

Maybe you need to install the wiringPi/Python package first?

This is the location for that: https://github.com/wiringPi

-Gordon

this program didnot work

[texy]

You need to install 'wiringpi for python', not wiringpi native as that is for C only.
See here :
viewtopic.php?f=32&t=10010&start=100#p162668

Texy

cool,
you'll need to show some interest and engagement in resolving your problems. If you expect people to help you you'll need to explain what you've done and in which way it has failed. A simple cry for "doesn't work, tell me exactly how" most often doesn't work.

Cheers,
Andi