Nextion Enhanced GPIO port to control LED

1

Hi folks,
I tried to use the GPIO, using Nextion IO adapter from ITEAD:
https://www.komputer.de/zen/cache/images/2/275da3c66d42a5abe4dea9dcb9b503e7.image.550x550.jpg

Osci prooves that the PWM signals (ports 4 to 7) arrive at a MOSFET driver board having optocoupler inputs:

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The 5050-LED strip howerver is constant on.
Using non-PWM signals from ports 0 to 3 renders the same result though.

anyone has any expierience doing that? Any other one having an idea?

please advice.
thanks
Walt

2

If you are sure there is a valid PWM signal, it’s something with your driver board.
It’s designed for DC 5V>24V the Nextion output is minimal 3,0V and max 3,2V !
That could be the problem in your case.
When there isn’t a good signal, in default the driver board will continue stay active.
(20% duty, is 80% output !)

3

The nominal output current of the Nextion GPIO is 1mA - most times not enough to drive an optocoupler. Since, on top of that, the logic voltage is 3.3V (the 5V standard is outdated in industrial designs), you‘ll need a combined buffer and level converter like TI‘s SN74LV4T125 to drive your board.

4

thank you guys, was apparently a classical think-before-solder fail: the small Nextion IO Adapter which comes with the needed cable and gives you the 8 GPIO pins plus 5V. But 5V supply does not mean 5V signal, right?
So not even having 3.3V supply for a level shifter, I went for the IRF5020 mosfet breakout boards (no optocouplers), one for each channel

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.
works like a charm :). Thanks again for getting me on the right track.

1 Like
5

Do you have a link for this?

6

just google “IRF5020 mosfet breakout” or go 1 stücke IRF520N Top Mosfet Taste IRF520 MOS Fahrer Modul Power MOS PWM Dimmen LED|mosfet module|mosfet drivermodule for arduino - AliExpress