nRF24L01 Can i transmit while receiving

For one of my projects i need to transmit data while receving with nRF24L01 can i do that i am using an Arduino UNO R3 and RF23-master library please help thanks

You need to provide a lot more information about what you want to achieve.

Do you mean you want the nRF24 to transmit while receiving? I don't think it can. But transmitting or receiving takes such a short time that it can be almost simultaneous.

...R

You can not transmitt and receive at the same time on the same frequency, period.

Think about it, the transmitter will make the receiver deaf to what it is supposed to be listening to.

The two have to be on different frequencies separated by some distance. In the Ham radio world you get radio repeaters that do this. They are at least 1MHz apart and even then you need high Q cavity notch filters before the receiver, these are about the size of milk bottles.

Thanks all of you but i wonder is there any wirwless communication module that can handle this job?

So, answer Robin's question. Think about it. If both TX and RX are in the same medium and frequency, did you read what Mike said. Can your application use different mediums (like RF and IR mix)?

Google is your friend.

The nRFs come very close to simultaneous transmission and reception when the acknowledge payload feature is used.
The sending station is passed back a packet from the addressed node.

In a shared medium only one node may transmit at a time, or collisions occur.

NewStudent:
Thanks all of you but i wonder is there any wirwless communication module that can handle this job?

Well you haven't said what "this job" actually is so it is hard to say. Most half duplex systems can look like full duplex systems with the right protocol. The Xbee for example does that for you. Very few applications need full duplex, so explain why yours does.

I guess a simple solution would be two pairs of nRF24s working on different channels. But then there is the interesting fact that the Arduino can only deal with them one at a time.

We await the OP's dissertation on his project with interest.

...R

While I have never tried it, I see no reason why two nRFs should not work in one system,
they are just two SPI devices with medium power requirement.

well if you get 4x nRF's you can transmit and receive real time :smiley: if you would like to use 4x nRF's on your project i don't see anything hard here.

well if you get 4x nRF’s you can transmit and receive real time

It is hard to transmit and receive in anything but real time. Or is this another famous miss typing.

Robin2:
I guess a simple solution would be two pairs of nRF24s working on different channels.

But as I said before look at this:-
Reciever spec.png

Grumpy_Mike:
But as I said before look at this:-

That's way above my pay grade? What does it mean?

Perhaps it means there would be data collisions and retries?

My suggestion in Reply #7 was not intended to be taken seriously. In any case this is all academic anyway until we know what the OP really needs.

...R

What does it mean?

It means that with a maximum selectivity of -27dBs of two different channels you don't stand any chance of having a TX and RX co-located.

It is hard to transmit and receive in anything but real time. Or is this another famous miss typing.

Let's say i use the PA version of nRF24L01 long range (packets can be lost easy by other different phenomena)packet size 32bytes and I want to send a file that got inside
30.656 bytes that's 958 packets not sure the speed of transmitting one packet (need to do a reseach) but
let's say it is 15ms * 958 packets = 14.370 ms = 14.3 secons. (ofc that depends on the speed of the nRF..etc but that's just an example)

Now think that you want to transmit that and it gonna take you minimum without checking if the packets are received or not and you need in the same time to transmit another huge file divided in a lot of packets in my case i would use 4x nRF's to transmit info and receive info without losing time.

Well that's just my opinion I don't know and i don't see any lately OP comment so he gonna take the final
decision of what he needs.

D.60

Grumpy_Mike:
It means that with a maximum selectivity of -27dBs of two different channels you don't stand any chance of having a TX and RX co-located.

I have never understood how to interpret those dB figures. As a matter of curiosity what number would be needed if they were to be able to function?

As a separate issue, I wonder if there would be more or less of a problem if they are all on the same channel and distinguished from each other by different addresses.

And, in either case, I wonder if a problem only arises in the event that both transmitters broadcast at the same instant. The project I have made sends a message once every 100 millisecs so I suspect the chance of two broadcasting at the same instant is low. nRF24 messages are only a max of 32 bytes so Tx time is very short.

Still no response from the OP.

...R

As a matter of curiosity what number would be needed if they were to be able to function?

Well ideally -60dB but maybe -54dB would do.

Yes the problem is only when you transmitt and receive at the same time, like it asks in the thread's title.