How to avoid data collision in a network of NRF devices where only 2 NRF want to communicate with each other and others dont get this data ?

[Harshal Kadlak]

Hello,

We are using NRF24L01 as a transreceiver. We have a network of NRF devices operating individually and we want one NRF to communicate only with its respective NRF. However the data collision happens during this. The NRFs in the network also receives this data despite keeping the different frequency.

We cant have multiple frequencies for our every product.

So, is there any way to avoid data collision / interference so that only 2 desired NRF will communicate with each other and other NRF devices in the network wpn't get that data ??

Thanks and Regards ,

Harshal

 

[Hung Bui]

Hi Harshal, 

Do you use any protocol with the nRF24L01 ? For example Enhanced Shock Burst ? 
How do you configure the address ? 
Could you show how exactly you configure different channels for each pair of devices ? When the channels are close to each other they can leak but I don't think they would if the channel band a far away from each other. 

[Harshal Kadlak]

Yes, we are using Enhanced Shock Burst.

Also, the channels are close to each other i.e. all the NRF devices in the network are operating very close to each other.

We configure different channels for each pair of devices from the microcontroller side via its firmware. 

[Harshal Kadlak]

ovrebekk said:

Do you know why you picked the 250kbps data rate in the first place, if you don't need long range? 

It was for the POC and sadly we sticked to it.

ovrebekk said:

If you change to 2M mode instead you should reduce the packet on air time by a factor of 8, which will reduce the energy consumption of each packet transmission and reception considerably. 

Yes, thanks a ton !!

[ovrebekk]

Hi Harshal 

Harshal Kadlak said:

It was for the POC and sadly we sticked to it.

And now you have devices in the field so you are unable to change it?

These things happen unfortunately

Harshal Kadlak said:

Yes, thanks a ton !!

Glad I could help!

Best regards
Torbjørn

[Harshal Kadlak]

ovrebekk said:

And now you have devices in the field so you are unable to change it?

No we dont have these devices in the field but we soon will !! We have been in the development phase so far.

So trying to fix this for once and all !!

ovrebekk said:

These things happen unfortunately

Yeah they do !!

ovrebekk said:

Glad I could help!

Thank you so much !!

Will get back to you if any queries we may come up with regarding all these.

Regards,

Harshal !!

[Harshal Kadlak]

Hello,

If the PTX is transmitting 3 different commands to a PRX, so when first 2 are sent the third doesnt get sent. And after next power ON, that unsent third command gets sent first.

We have cleared the TX FIFOs on the power ON and yet this happens.

[ovrebekk]

Hi Harshal

Harshal Kadlak said:

so when first 2 are sent the third doesnt get sent

Why does the third packet not get sent? You never pulse CE to send it, or will it be sent but not acknowledged by the PRX?

Harshal Kadlak said:

And after next power ON, that unsent third command gets sent first.

Can you elaborate what power ON means? Are you powering off and on the host MCU? 

I assume the nRF24L01+ remains powered during this time, since the FIFO is retained? 

Harshal Kadlak said:

We have cleared the TX FIFOs on the power ON and yet this happens.

Could you check the value of the FIFO_STATUS and STATUS registers before and after attempting to clear the TX FIFO, and let me know what they are?

Best regards
Torbjørn

[Harshal Kadlak]

ovrebekk said:

Can you elaborate what power ON means? Are you powering off and on the host MCU? 

Yes we power OFF-ON the host MCU of the PTX.

ovrebekk said:

I assume the nRF24L01+ remains powered during this time, since the FIFO is retained?

Yes, we dont power ON OFF the NRF.

[ovrebekk]

Hi

What about the status of the configuration/status registers? 

Can you try to read out the register status when the nRF24L01+ device is in the problematic state?

Harshal Kadlak said:

Yes we power OFF-ON the host MCU of the PTX.

Is there any way for the host MCU to know during boot whether or not the nRF24L01+ has also been reset? 

If the host assume the nRF device has been reset while in reality it is still running then you might not enable it correctly. 

Best regards
Torbjørn

[Harshal Kadlak]

ovrebekk said:

Is there any way for the host MCU to know during boot whether or not the nRF24L01+ has also been reset? 

No the NRF is not reseted, the problem occurs when only the host MCU of the PTX is reseted. Then the previously unsent commands get the send when the host MCU is powered up.

[ovrebekk]

Hi 

The question is if the host MCU can know that it has been reset but the nRF24L01+ has not? 

If the host can distinguish between this type of reset, and a full power reset where both the host MCU and the nRF24L01+ gets reset, then you can run a different init sequence in either case. 

Best regards
Torbjørn