Electronic – arduino – When powering a Nrf24L01 hooked up to an arduino by external battery does ground still go to the Arduino ground

The capacitor is definitely helpful for these sensors. Its absence manifests in rather devious ways, as I learned when working from a tutorial that didn’t have a capacitor: When testing the IR decoding in isolation, it might very well work. Once you add other elements to the circuit (in my case, an RGB LED), the IR decoder suddenly starts generating nonsense readings.

I would suggest you edit this question and use the code format to pretty print your code as it's very hard to follow the way it currently is.

The value for the pipe variable is an address, more or less the equivalent of your computer IP address: when a message is broadcast into the air all the potential receivers will filter out any message not corresponding to an address they are interested into.

In particular your nRF24L01+ chip is capable to listen for up to 6 addresses.

Another address is the one you use to transmit, so that everybody receiving your message knows who has sent it and to reply to.

So, in your code radio.openReadingPipe(1,pipe); // pipe value being 0xE8E8F0F0E1LL

means hey, radio, use the second pipe to listen for any message incoming from address 0xE8E8F0F0E1LL, while radio.openWritingPipe(pipe); // pipe value being 0xE8E8F0F0E1LL

means hey, radio, when sending messages identify yourself with address 0xE8E8F0F0E1LL.

That's the explanation for the pipe thing and in a short form: those two values in your sketch must match.

Regarding the fact you are not receiving the message, I suggest the following:

1. try setting the message payload size to a fixed value with radio.setPayloadSize(1)
2. add a 1uF capacitor short between GND and Vcc on your nRF24 board
3. try to use the most reliable configuration which, on the nRF24L01+ is the 250Kbps with maximum PA level by setting radio.setPALevel(RF24_PA_HIGH); radio.setDataRate(RF24_250KBPS);