Arduino Mini Pro and Receiver

I am working on a ornithopter project. For the project I am using a Spektrum Receiver and an Arduino Mini Pro. I have encountered a problem that I found no resolution for. I have tested the circuit (without external battery) on a normal breadboard connected to my PC and everything seemed to work but when I have connected the circuit up onto the actual ornithopter with a 7.4V external LiPO battery it does not.

Both the receiver and the Arduino get the power as I turn on the switch, and Arduino does the first part of the code where it moves the servo's to 90 degrees. Then the code tells it to wait for a signal from the receiver but it seems as if the Arduino never reads/receives the signal as there is no response. Although the receiver is on and the light on it is also on (which means its connected to the transmitter)

I have tried changing the digital pin to another pin but it did not resolve the issue and I dont think it is the problem in the wiring since the servos seem to work fine.

Maybe I am missing something or maybe there is some other problem. Any assistance would be appreciated.

Link to the photo of the circuit : |500x375

To analyze the response to receiver data, you should put serial debug statements in your program, so you can see what it’s doing.

Have you connected all ground lines? How do you power the servo? How do you power the Mini? Does it run on 3.3V or 5V?

DrDiettrich: Have you connected all ground lines? How do you power the servo? How do you power the Mini? Does it run on 3.3V or 5V?

I have connected all the grounds from the battery, Arduino, Receivers and servos.

The servos are powered the 2S LiPo battery, same as the Arduino. Arduino is a 5V and so it can take input voltage up to 12V.

The servos and everything else seems to run fine and the circuit can work autonomously but when I connect the receivers and make program the receiver to read the receiver, it does not work.

The receiver and the code work with a normal Arduino UNO and the big arduino breadboard but not on my ornithopter.

There may be a problem with the receiver power, the 5V regulator of the Mini doesn't source as much current as the Uno regulator.

You program for Pro Mini 5V 16MHz? You disconnected the programmer, which uses the Rx/Tx pins?