RF link sticking

[8igDiaz]

I’m pretty confused here, trying to send a simple 1–4 signal between two microcontrollers using a basic RF link
I’ve got an LED on the receiver that lights up when it gets a signal (using a 4.7k pull-up)
The thing is that sometimes the LED just gets stuck in the ON state. It even happens right at powerup sometimes
I thought the transmitter was stuck, but the LED stays lit even if I physically remove the transmitter from the circuit!
Checked the scope and it just shows the usual random noise, nothing changes when the LED sticks.

If it’s not the transmitter and the scope doesn't see a real signal, what could be locking my receiver pin high?

 

[voltagepathmaker]

Seems like the receiver is just picking up random noise, those basic RF modules tend to drift if the input isn’t clear. A bit of filtering or a stronger pull-down often sorts that out.

 

[barfle]

Is there an oscillation in the receiver? RF leaks feedback and board layout can be critical.

 

[voltagepathmaker]

Yeah, that sounds like it could be it. If the receiver is messing up or catching its own interference, that would make sense why the LED is stuck on.