ESP32 Forum

Hello all, I'm testing the Light example
https://github.com/espressif/esp-mdf/tr ... _kit/light

I tried to compile this and attach an RGB in the Gpios and works great:
https://twitter.com/martinfasani/status ... 5026150400

And as I have a lot of P-Channel mosfets in my garage and RGB leds I though to make my own demo Lights.

So the idea was to receive the PWM signal in the documented GPIOS:

GPIO4 O PWM_R output control
GPIO16 O PWM_G output control; alternate UART interface (URXD)
GPIO5 O PWM_B output control; alternate UART interface (UTXD)

And use them to feed the gate of a Mosfet. The issue is, that this P-Channel mosfets that I have, are closed on HIGH (Also it will be turning off on high instead of ON )
So I though to ask here to the electrical minds more advanced than mine...What would be the best way to go ?
To invert the PWM signal and still use a P-Channel Mosfet ? (Is that possible to do in the ESP32)

To use a different Mosfet that will open on HIGH ? (Tell me what model so I will look in the datasheet)
Or just comment how you will do it or what is wrong in my approach. Basically I would like to use the PWM signal to control many leds instead of just one.

I think the best and easiest way to do that is to invert the GPIO output signal in esp32.

Refer to func_out_sel_cfg register in components/soc/esp32/include/soc/gpio_struct.h.
For example, if you want to invert GPIO18, you can use the following code to do that, after initializing light driver. We will add an interface into idf for this kind of scenario.

Thank you very much costaud!
That looks like the smartest solution since I can use the P-Channel mosfets.

I though also that we can power the RGB Channels directly from the GPIO, taking in account the they don't consume more than the allowed mA.
Will start a project in Hackaday to make your own smart lights with LED left overs:
https://hackaday.io/project/163672-esp3 ... led-panels

An alternative way without needing a lot of components is to use just one Quad Bus Buffer like 74H125 that supports up to 35 mA per output pin but has two great advantages:

- Separating the Logic from the Led power
- Being able to use another voltage ( In the 35 Leds example on the Hackaday page I'm using 5v instead of the 3.3v from PWM coming grom ESP32 )

Thanks!
Another option I found to separate the Logic from the Led power line, is to use one 74HC125 Quad Bus Buffer

Then you have the advantage of not soldiering 3 different components with a max output of 35 mA which is enough to power quite a lot of 5mm leds (35 in my case)
But I will try inverting the PWM in the next model just for fun, great solution!

Photos of the result: https://hackaday.io/project/163672-esp3 ... led-panels