Direct TCP/IP connectivity between Arduinos using a nRF24 or nRF52 radio link w/RF24Ethernet

 Setting up direct TCP/IP connectivity between Arduinos using a nRF24 or nRF52 radio link w/RF24Ethernet

 Utilizing the new functionality of the RF24Ethernet library

 With some recent experimentation and prototyping involving the lwIP IP Stack, I was able to modify the RF24Ethenet library to function standalone, without the need for a Linux/Raspberry Pi device running RF24Gateway. This allows users to directly connect multiple Arduino devices using the RF24Ethernet library, utilizing TCP or UDP protocols to communicate between devices.

The RF24Ethernet library API is based on the official Arduino Ethernet API, so users utilize the same coding style to communicate over nRF24 or nRF52 radio links.  

Setting things up:

1. The first thing to do is verify you have working radios. With nRF52 devices, they are built-in so, there is not much to worry about, but with nRF24 radios, users need to keep in mind power supply and wiring issues, so testing using the official gettingStarted sketch included with the RF24 library is recommended before attempting this.

 2. For now, users need to install the RF24Network library from ZIP file, then edit the RF24Network_config.h file and set the MAX_PAYLOAD_SIZE to 1514. This will be all be configured automatically once the current updates are deployed to the main branch of RF24Ethernet. This document will be updated at that time.

3. Install the RF24Ethernet library manually from https://github.com/TMRh20/Sketches/tree/master/RF24Ethernet-lwIP Users need to copy the RF24Ethenet files into their Documents/Arduino/libraries/RF24Ethernet/ folder. Note: Once deployed, the updated library will be available from the Arduino Library Manager. Users may need to uninstall/reinstall to get the latest updates.

 4. Install the Arduino lwIP library using the Arduino Library Manager as required for non-ESP32 & non-ESP8266 devices which already include lwIP.

5. Run the included examples from the Headless directory in the RF24Ethernet examples on two devices. 

 

What to expect:

The main server example sets up a RF24Mesh 'Master Node' which handles addressing and address look-ups for all other nodes. Nodes not in range of the Master Node will attempt to connect automatically via routing traffic through other connected nodes. 

The client examples simply connect to the Master Node and request an HTML based web-page. 

 In a real life deployment this activity may be reversed. With the Master Node running a modified Client example, and sensor or other nodes running modified Server examples, the Master Node could then connect to each device in turn and retrieve data as required.

To designate a master node, simply call the following before calling mesh.begin()

mesh.setNodeID(0);

then from the main loop()

 mesh.DHCP();

 

 Things to Note: 

 RF24Ethernet makes use of two separate IP Stacks, the older, unmaintained uIP Stack works on smaller devices like Uno, Nano, Mega, etc, while the newer, lwIP stack is used automatically for devices >50MHz CPU speed, including the Arduino Due, ESP32, ESP8266, and nRF52 based devices using the nrf_to_nrf radio library.

To ensure you are using the lwIP stack, users can #define USE_LWIP 1 & #define RF24ETHERNET_USE_UDP 1 in the RF24Ethernet.h file or prior to compilation.