RN-41 Bluetooth module (noise problem) please help

Wireless & IoT
1

Hi,

I’m having some strange problem and I need some help with an RN-41 module please.

I’m building a light detection circuit (using LEDs and a light receptor), which sends a message to a PC, by bluetooth, when light is detected. Everything works fine when the bluetooth module is only powered (without starting communication), but when I start the communication with the PC a very strange noise appears in the light receptor output. I already have decoupling capacitors to avoid noise but still I have this problem. What could be the problem? I’d appreciate very much some help.

Thanks a lot.

Best Regards,

João

I’m attaching some images so you can identify the problem better. You can see the before and the after starting the communication… Thanks.

2

That trace does look pretty troubling. It would probably help to know what you’re using for a light receptor, and to see some schematic.