Is NRF24L01 sleep mode necessary

Projects Networking, Protocols, and Devices
1

Hi All,

I am building a simple door and window sensor.

I am using a reed switch, Arduino Nano and an NFR24L01.

the key is I need some to be battery operated.

Some I can run from a plugged in psu so I can happily use a master slave transmit and response (polling).

however I do need to limit current on the battery powered sensors.

my plan is that I will use the reed switch via pinMode(sensor, INPUT_PULLUP) then transmit only when there is a change of state.

as I will only transmit when there is a change of state, do I really need to put the NFR24L01 in a powerdown state, or will it be constantly receiving and filtering out the non needed data?

Many thanks

2

JonMiles:
as I will only transmit when there is a change of state, do I really need to put the NFR24L01 in a powerdown state, or will it be constantly receiving and filtering out the non needed data?

It's not clear which of the two nRF24s you are talking about.

If you envisage one of them only sending data occasionally then of course it can be powered down between transmissions. However the listening nRF24 has to be listening often enough to be sure that it won't miss a transmission.

Another factor is whether you want the receiver to be able to tell when the sender has failed, and is not merely asleep. One way to deal with that is for the sender to send a message at regular intervals - say 4 times per second - even if the state has not changed. If a transmission takes (say) 3 millisecs that would require the sender to be on for about 15 millisecs per second or only 1.5% of the time. That may be sufficiently frugal for adequate battery life.

If the sender transmits 4 times per second then the receiver can be sure of intercepting a message if it is listening for (say) 30 millisecs every second - so it could be asleep for 70% of the time if detecting a message once per second is sufficient.

...R

3

Sorry, didn't realise there were two types.

I am using

this is purely for the transmitter, there receiver will be powered by 5v transformer.

I was going to send a check message every minute to check for connection.

I was only going to be sending an acknowldgement to the slave then it can go back into sleep mode.

4

JonMiles:
Sorry, didn't realise there were two types.

I did not mean two types. I just meant your receiver and your transmitter.

...R

5

ooops sorry.

its the slave that I wonder if it is going to save much battery by putting it "to Sleep"

6

JonMiles:
its the slave that I wonder if it is going to save much battery by putting it "to Sleep"

I don't know - the projects I have been building need to be operating all the time. The details are almost certainly in the Nordic nRF24L01+ datasheet.

Using sleep mode is unlikely to do any harm, so why not try it?

...R

7

Hello ,
If you are looking for low power consumption due to batt. ops. for your nRF24L01 radio. Have look at the MySensor site.
Succes,
ilioSS

8

ilioSS:
Have look at the MySensor site.

A link would be useful :slight_smile:

...R