The purpose of this repository/example is:

1. A FreeRTOS Nabto Edge integration.
2. Show how a typical embedded target with FreeRTOS and the LwIP IP stack works with Nabto Edge.

The example consists of the FreeRTOS linux simulator, the LwIP stack running simulated on linux using a tap interface and the Nabto Edge embedded SDK.

FreeRTOS linux simulator, the example is based around the simulator. The simulator is running the LwIP thread and a thread running the nabto edge example.

LwIP, the example uses the LwIP IP stack integrated on linux using a TAP interface. The tap interface is a layer 2 integration between the LwIP stack and the linux system where the demo is running on.

Nabto Edge Embedded SDK, the Nabto Edge example uses the Embedded SDK to create a Nabto Edge device. The example mimics the simple_coap example from the embedded sdk. It is a Nabto Edge device with a CoAP server responding to the /hello-word path.

Implemented:

• FreeRTOS integrated with Nabto SDK
• LwIP TCP, DNS and UDP integrated with Nabto SDK
• LwIP via TAP interfaces.
• Simple CoAP demo

TODO:

• libpcap integration for LwIP such that LwIP can be used directly with ethernet interfaces.

git clone --recurse-submodules https://github.com/nabto/nabto-edge-freertos-simulator

It is a plain CMake build.

mdkir build
cd build
cmake ..
make -j

The integration tests tests the nabto implementation against lwip and FreeRTOS.

./build/integration_test

Example output

vscode@2b86f239ccb5:/workspaces/nabto-edge-freertos-simulator/build$ ./integration_test
Starting lwIP, local interface IP is 192.168.100.200
ip6 linklocal address: FE80::12:34FF:FE56:78AB
status_callback==UP, local interface IP is 192.168.100.200
Create device test passed
Future resolve test has passed
Event queue test has passed
DNS test has passed
UDP test has passed
TCP test has passed

dependencies: nftables

./setup-tapif.sh ./build/nabto_demo

setup-tapif.sh creates a new tapif and setup NAT rules in the firewall using

To not contaminate your system with custom tap interfaces and firewall rules the example can be run inside a docker container.

docker build . -t edge-freertos docker run --rm -it --privileged edge-freertos

Make a new git clone and build the software inside the container.

Open the project in vscode and start hacking using a remote-container workflow.

This is most likely not going to work for an explanation read the VirtualBox notes. TLDR: Multiple macs sending on a single wifi interface in client mode is not a good idea.

If the demo app is running inside a docker container mdns discovery is not working outside the container.

mDNS only works on the local machine if the simulator is not running inside a container and the mDNS client is also running on the local machine, due to multicast on the tap interface not being routed to the primary network interface.