NRF24le1 max no. of IR nodes?

[Matthews]

Hi friends,

I am doing a project in NRF24le1 using RF communication with multiple nodes with a host using star topology.

Could you suggest a Protocol that supports connecting upto 100 nodes with a single host

[ovrebekk]

Hi

We don't really have any out of the box-protocols well suited for doing huge star networks, you would probably need to do something proprietary on top of the ESB protocol.

If you have a single host talking to multiple nodes then you can have the host interrogate one node at the time, and differentiate the nodes by using unique RF addresses.

If you use the ACK payload mechanism you can have the nodes prepare some data for the host in an ACK payload, and as soon as the host sends a packet to the node the ACK payload will be sent in return.

The simplest implementation would have the nodes in RX mode constantly, waiting for the host to send a packet, but this wouldn't be very power efficient. If you need a more efficient implementation you can have the host interrogate the nodes at a fixed interval, allowing the nodes to sleep in between packets.

Best regards
Torbjørn

[Matthews]

Thank u torbjorn,

But as per ESD protocol a maximum of 8 nodes can only be connected at a frequency channel. So i am thinking to design like a 10 or 12 node group in different different frequency channel?

Is it reliable if i switch the frequency channel of host periodically and search for response from nodes in a group at a particular frequency

thanks and regards

Matthews

[ovrebekk]

Hi Matthews

I assume you are referring to the number of pipes in the radio, which is limited to 6 in the nRF24L series and 8 in the nRF5x series, but this is not really a limitation on how many devices you can talk to.

It is possible to change the RF address registers in the host dynamically, allowing you to talk to a virtually unlimited number of devices as long as you reserve a unique time slot for each one.

If you want to assign different frequencies to different nodes this is definitely doable, you can change frequency in the radio as easily as changing the RF address. Any change in the RF configuration require you to go into standby mode, change the registers, and power the radio back up again, which can all be done in a couple of hundred microseconds.

Best regards

[Matthews]

thank you mr.torbjorn .could you tell me how to connect unlimited number of devices allotting different time slots.This is done by gazell communication i guess. Could you share the link of any example project to know the working in details.

Looking forward to hear from u

Matthews

[ovrebekk]

Hi

I don't think we have any simple examples for this unfortunately. You might be able to use Gazell, but I think it is simpler by just using ESB.

The basic operation would be something like this:

1. For X devices, prepare a list of unique addresses for each device.
2. Configure each PRX device with it's own unique address from the list.
3. On the host side, go through each address in the list and do the following:
   4) Change the host TX address and RX PIPE0 address to that of the device you want to talk to.
   5) Send a packet to the device with any new information you have for the device
   6) On the device, add any data for the host into an ACK payload
   7) Have the host send another packet to pick up the ACK payload from the device
   8) Repeat from 4, until you have gone through the entire list of devices.

Best regards