How to detect receiver (smartphone) with a wireless charger transmitter (base)?

Thread Starter


Joined Oct 8, 2022
My end goal is to build a circuit with a wireless charger transmitter module and a led indicator that turns on when the receiver is detected and wireless charging is occurring.

I’ve been reading about the analog pings the TX uses to detect RX, Foreign Object Detection (FOD), Q-factor measurement… But I feel I’m nowhere nearer to the actual circuit that can implement this. I have a wireless charger that I opened out of curiosity. Its base lights up blue when plugged in and red if an object is charging on top of it. So basically, exactly the functionality I would like to replicate. I could clearly see a micro-controller in the PCB, and that’s where my reverse-engineering skills stopped! :’)
I couldn't find online a circuit of a transmitter with a micro-controller that measures loss in Q-factor or FOD (cf.

Any tips or resources on how I can achieve this are highly appreciable!