Bug Filed on 01-25-2016: PCA9685 device add fails

1. What OS? (Wheezy or Jessie)


2. What class/size SD card? (ex. class 10 16gb)


3. What Model Pi? (A+, A, B+, B, Pi2)


4. Please describe the bug / issue. Attaching any relevant screenshots would be very helpful! Thanks in advance.

Device add fails, see screen shot

Weird…It’s been working. Maybe latest release broke something. @svazir @akaranfilian for you guys to test

This worked for us when we tested on production. Can you give us the errors from the webiopi log which can be ontained using the following command. tail -f /var/log/webiopi

Also can you try renaming the sensor to something different, sometimes if the sensor has been added it does not let you add it with the same name even if it is removed.


Looks like you called it with the name error:

2016-01-25 13:19:24 - WebIOPi - ERROR - Device already exists
2016-01-25 13:21:38 - WebIOPi - ERROR - Device already exists
2016-01-25 13:25:33 - WebIOPi - ERROR - Device already exists

Although now that I look back its already in the dashboard???
Also, it doesn’t appear that I can change the sliders on any of the channels, they are all at 1

Here is a screen shot of what I see

@svazir If you could import to Trello. I can help test this too.

@bestes its imported into trello

@ats1080s and I talked about this…you need to add a device to a channel on the PCA9685 in order for the sliders to appears on the PCA9685

Hi, I bought this device and it seems that connects correctly. When I go the the GPIO I can see the PCA9685 in GPIO SDA. Is this correct ?

Now I cannot see how to use this device. An example, maybe dumb. Can I feed through PWM the voltage applied to a normal LED and control this way the luminosity ? Is this possible ? This would make me, and more people hopefully, understand the workings and control.

Is there any other experiment you can suggest in order for us to understand the workings of this device ?

Thanks and every suggest in usefull.



Hey Neiva,

Yep, You can hook up the LED to the PWM and control the luminosity! Just like a light dimmer.

Check out this diagram :slight_smile:


Our full list of wiring diagrams is here:


For other things you can do with the device, you can add a servo.


Please reach out with any further questions! Hope this helps.


Thank you. I had already done what you suggest but I was choosing the wrong device so I neves managed to see the sliders.

Thank you for your support.

I am thrilled with this. I now control the blinds of my study as well as some lights.

Just waiting for the camera.

Congratulations for this project.



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