nrf52 2.4Ghz project

[pavan]

Project # Student feedback Remote ( with 60 to 70 students in a class room )

We are developing Student voting remote project.

The product will be similar to below china make & will have 7 keys and will be operating on 2 AAA size battery with 2 year power back up requirement.

www.enjoyvote.com/.../products.php

www.enjoyvote.com/.../products.php is based on WM9218 RF IC + MCU.

We want each remote should have Unique ID & should pair with one Gate way dongle in a class room and dongle will be connected to Laptop to capture the data . should not overlap with the next class room gate way.

We have selected nRF52810 –QCAA R for the same & we suggest nRF51802 also one more variant .

For above requirement we feel the 2.4GhzS protocol mode will suit than the BLE mode Please confirm and also share the software and documents for Nordic proprietary 2.4Ghz protocol .

Please confirm which protocol is suitable for such product.

Thanks in advance Pavan S K

[Hung Bui]

Hi pavan,

With 70 nodes, it's correct that it's not a good idea to use BLE.

I would suggest you to try ESB (our 2.4GHz proprietary protocol). You can have a look at the userguide here. It's a star network and only support up to 8 concurrent slave. However, in your case you can use the same pipe for all nodes. So basically the PRX (the host) listens all the time and all the nodes send to same radio address. Each node will put its ID into the payload.

When a button pressed, a node will start transmitting let says 10 times, with some random delay between them. The random delay is to avoid congestion.

Depends on the application, you can decide if the PRX need to send ACK back to the PTX or not, up to the application. The ACK packet will have the same address for all node, but there will be an ID in the payload of the ACK packet. Using ACK you can avoid the node have to re-send packets many times.

Another option for you is to our Bluetooth Mesh. It would be useful in the case that it's a big class room that the PRX might not be reached directly from the node. The disadvantage is a packet will be rebroadcasted by all nodes causing more traffic on the air.

[Hung Bui]

Please have a look at the ESB example provided in our SDK.

By default it was made for 1 PTX and 1 PRX. But you can modify the example to test with several PTXs and add the ID inside their payload.

The addressing is explained in the user guide of the protocol in the link I sent above.