Sliding/Dimming LED PSU w/ RPi 3 & Blynk

Hey everyone.

I’m trying to control the brightness/intensity of my LED lights through the Blynk application. While I’ve had success with the combination of the on/off button widget and a relay, I’ve come up short on the Slider widget.

Component Breakdown:

  • Raspberry Pi 3 +B
  • LED Power Supply Unit (PSU)
  • LED lights

So the Slider widget for the RPi 3 comes with one option for digital pinning, which is the GP18 PWM (pin 12). The LED PSU comes with a 3-1 dimming function, which allows the user to dim in multiple fashions, including PWM. Furthermore, the LED PSU comes with DIM+ and DIM- wires, which are separate to that of the V+ and V- wires, which connect directly to the LED lights.

As I have it:

GP18 PWM (pin 12) —> Dim+
Ground (pin 14) ----> Dim-

For whatever reason, nothing happens when I adjust the slider in this configuration. I’ve tried different GPIO cables but that doesn’t seem to be the root cause. Does anyone have any insight to share?

can you share the link / exact name / photo of the device?

1 Like

hey @vshymanskyy, I love what you guys are doing with Blynk.

What I recently noticed with the data sheet for the driver is that while it can be dimmed via PWM, it’s listed as being 10V. I don’t think the GPIO PWM pin for the RPi 3 +B is pushing that much potential but I could be wrong. If it’s not, and instead 5V, then that could possibly be the reason behind the dimming widget’s ineffectiveness.

Here is a link to the datasheet to the particular power supply that I’m working with:


On a positive note, I did have luck with the timer widget today.

Edit: The pages that pertain to this discussion are page 4~5 on the datasheet.