Question: FL5150 LED Dimmer - replace a analog potentiometer with a digital one



  • Hello,
    I need some help,

    I'm trying to figure out how to build a remote led dimmer.

    Now I saw great Scott, and he build one with an FL5150.

    I thought this would be a chance to combine it with an nrf52 module that I use for my other nodes.
    The question is, can I replace the potentiometer with a digital one.

    0_1560755550927_661cc184-e1da-4245-8e3f-94ecb9736306-image.png

    I looked at a AD5241BRZ1M it has 256 steps from 0 to 1mio (it only needs 0 to 250 though, but the 200ohm seems to be too little, correct me if I'm wrong and the 250ohm are too expensive to my liking.

    Or is there another way of doing this?

    thnx!



  • @omemanti i did some digging, looks like a DAC will solve my problem. If it works I'll close this request. Fingers crossed.



  • Please report the results. I thought this dimmer chip looked interesting, but it seems to be optimized for manual control with a pot. Like you, I want something to control with MySensors.



  • @nagelc just bought some things to get me started, I have a fallback, just use digital resistors, in series, if needed.

    After reading the datasheet again, im not so sure the DAC will do the trick, it's the pull-down resistors that determine the voltage, so I think a DAC won't work.



  • Since the dimmerpin needs a resistor to ground. I placed a 1M ohm digital potentiometer and used it to controll the dimmer. so far it works (a bit).
    1M ohm is to much, so maybe I can get is working with just one or two 100k ohm.

    I solderen together a very rough setup, and I can dim the light using a pro-mini 3,3v.

    It still has some flickering, and I think I need to get a MOSFET or something to pull it to ground to turn the light off.

    But so far so good.


 

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