nRF24l01

RE: nRF24l01

Janek Mann — Sun, 10 May 2015 07:02:22 GMT

Well, to be sure implementing a mesh network on top of the NRF51, from scratch, is not quite a beginners task. You might indeed find it easier in this case to build on somebody else's work in the Arduino ecosystem like this: maniacbug.github.io/.../

You could also have a look at this mesh network implementation hosted by Nordic: github.com/.../nRF51-ble-bcast-mesh (that one has some limitations as it is designed to co-exist with Bluetooth LE, but might be useful as it's already written).

My point regarding the benefits of the NRF51 is perhaps not entirely relevant to a beginner as it would be more important to have existing code to build on.

RE: nRF24l01

Daniel — Sat, 09 May 2015 01:10:52 GMT

I'm sorry, I don't understand it so much, and I'm also a beginner in arduino and NRF24. Can you explain it for beginners? how the NRF51 can help me to create a real mesh network? Benefits of NRF51 over NRF24L01+ for this purpose, libraries to use or links to any example or tutorial of use about NRF51 please?

RE: nRF24l01

Janek Mann — Fri, 08 May 2015 07:52:44 GMT

Hi Daniel, you certainly can, assuming that the PRXs are all set to receive on the address that the PTX is transmitting on. However you won't be able to use the built-in acknowledgement feature on more than one PRX (as otherwise the acknowledgement packets would collide). Also you wouldn't be able to use the built-in address matching for more than 6 PTXs so you would need to implement your own address scheme inside of the messages you transmit.

At this point you'd be basically using the NRF24 as a dumb transceiver pipe, more or less.

BTW I would use the NRF51 range for a mesh network today... the radio peripheral in those has many features that make them much better suited, especially due to the very close integration between the radio peripheral and the MCU / Timers (so you can very conveniently schedule the timing of messages / responses / beacons etc). It also allows to for example receive a notification after N bytes of the message have been received, so theoretically it would be possible to set up the appropriate acknowledgement message for the TX node you are receiving from while the message is still being received, allowing for a quicker turn-around time.

RE: nRF24l01

Daniel — Thu, 07 May 2015 18:45:20 GMT

Is this information 100% confirmed? Can I send data from one PTX to a lot of PRX using for this the same address on all nodes? (same pipe) I want to create a mesh network, and for this I need to send messages from all nodes to all nodes (for sure more than 6 nodes). Thanks!

RE: nRF24l01

Janek Mann — Tue, 03 Dec 2013 12:48:42 GMT

Hi zg,

if two or more PTX devices with the same address send a packet at the same time (or with overlapping on-air times), either one or zero packets will be received by the PRX, as the PRX can only receive one packet at a time. If the PRX is set to acknowledge the packet, more than one of the PTXs may interpret the acknowledgement packet as being addressed to them, giving the illusion that their packet was received by the PRX, hence not resulting in a retransmit of this packet from this PTX and a lost packet.

If the PTXs are using different addresses, it is still the case that one or zero packets will be received, however the acknowledgement would only be received by the PTX which sent the actually received packet, so the other PTXs can retransmit their packet.

RE: nRF24l01

zgxiao — Tue, 03 Dec 2013 03:32:07 GMT

Hi, Janek. Thank you for your reply. Do you mean that if two or more PTX devices send packets at similar time, one packet is surely to be recevied and the others lost? Best regards zg

RE: nRF24l01

Janek Mann — Mon, 02 Dec 2013 21:25:47 GMT

Yes, the multiceiver function is just for matching on 6 addresses in parallel, if you use the same address for for multiple PTX devices you can have more. However if you use the acknowledgement feature there is a risk that if two PTX devices send a packet at similar time, one packet may be received but both PTX devices may interpret the acknowledgment.