Pro mini working differently than Uno

I’ve got a small network of NRF24 radios connected through arduino Unos communicating with each other. I’ve tried to shrink everything by replacing the uno with a pro mini. I have created a small board to power the mini and the radio and provides 5v for the mini and 3.3v for the radio.

My problem is that for some reason, the mini’s don’t work. If I watch the traffic through the minis, I can see that everything is connected properly and the minis are receiving traffic. But they aren’t able to send anything. I’ve tried replacing every component and have verified that the exact same components that worked on the uno, does not work with the mini. The same sketch on both as well.

One thing I have noticed is that one the uno, the tx/rx light blinks distinctly, then turns off. On the mini, it stays constantly lit and when it tx, it gets slightly brighter.

I’m getting a bit frustrated with this and have done everything I can think of. Are there any common problems when going between uno and minis? Is the tx/rx light a sign of anything? Any ideas at all on the problem? I know the question is rather vague.

This is a link to the sketch I’m using

And I’ve attached a picture of the board that is powering the radio and mini. Forgot to include the values, but from left to right, its a micro usb, 0.1 cap, transistor, and another 0.1 cap.



It would be much easier for readers here if you post the code directly in the forum, or at least the link to the .ino file.

That said, it's a long piece of code - too long for me to try to figure it out.

Can you make your application work with two Unos only?

What happens when you replace one of the Unos with a Pro Mini?

Are the pin connections on the Pro Mini the same as the Uno or do you need a slightly different version of the code for the Pro Mini?


justind000: Are there any common problems when going between uno and minis?

No. It's the same chip, just a different shape.

justind000: Is the tx/rx light a sign of anything?

What tx/rx light? A Pro Mini has no tx/rx LEDs...

justind000: Any ideas at all on the problem?

Sounds like a power supply problem to me. Compare all your voltages very carefully at various places on the circuit.