NRF52840 to NRF24L01+ Wireless Communication with Arduino

 NRF52840 to NRF24L01+ Wireless Communication with Arduino

More on development of the nrf_to_nrf radio driver

So I've finally made some more progress on the development of the nrf_to_nrf radio driver that allows communication between NRF52840 and NRF24L01+ devices. The main and latest development is the functionality of using static payloads. I'd been playing around here and there for a few months trying to figure out why the ACKs kept getting rejected when using static payloads, since I had the driver working with dynamic payloads and even ACK payloads. It turns out the NRF24 devices will only send and receive ACK packets that have a payload size of 0 when using static payloads. The driver actually needs to set the payload size to 0 then switch back after sending/receiving ACKs. I should have guessed, but didn't figure it out for quite a while.

It's been quite interesting so far, this radio will handle payloads up to 127-bytes compared to the 32-bytes of the NRF24, and supports 8 'pipes' (for addressing) rather than 6. It still has a similar method of addressing, which many people seem to find confusing. It also can measure the RSSI and return a value rather than the NRF24 functionality of returning on any value better than -64 dBm. 

The main "downfall" is that the radio is software driven, unlike the NRF24, which handles a lot of functionality independent of the MCU, but that downfall on the other hand gives us direct access to the radio and its functionality. This opens things up a bit for what is possible with the radio. In order to achieve functionality similar to the NRF24 however, interrupts need to be used to handle radio events in the background, while the main software runs. This may prove to be something I'm not going to support, but will see how things develop with the Arduino platform and NRF52 board support.

Another interesting capability of this device is encryption. It contains a CCM - AES CCM mode encryption peripheral, that allows us to create encrypted and authenticated networks. I've been playing around with this functionality lately, and it looks like it can be incorporated into the library in a fairly seamless way. More on this later...

The library is currently available via the Arduino Library Manager, PlatformIO or you can grab it at GitHub if you want the latest modifications.