BSIM Demo

This repo showcases how you can use Babblesim to develop Bluetooth applications.

There are two demos:

GATT bug

In this demo, we are developing a Bluetooth device that uses the central role.

It connects to a peripheral device, and does a GATT service discovery, trying to subscribe to the heart-rate measurement characteristic.

However, there is a bug in the discovery. Using Babblesim, we can find it (hint it's in the commit history) much quicker than if we had to flash and debug on a real device.

We can observe discovery parameters at our leisure in any of the discovery iterations, and still have the Bluetooth link running. All the simulated peripherals also stop when we hit a breakpoint. This is pretty much impossible on hardware.

Using the demo

• Install VSCode + the devcontainer extension
• Open this repo in VSCode, click "open in container" when the pop-up appears
• Click "Run" -> "Start debugging"
• Use the debugger to step through code
• Simulation output is in the sim.log file
• Click the trace.pcap file to open a packet dump

Python demo

This demo showcases that you can also use Babblesim to develop Bluetooth applications using a different language or runtime than Zephyr.

In this demo, we have a very minimal Bluetooth "host" written in Python. It communicates with a Bluetooth controller that is in a simulation with a scanning device.

[host] <-- virtual UART (fifo) --> [controller] <-- Simulated RF (bsim) --> [scanner (controller + host)]

Both the controller and the scanner are built using Zephyr.

The python application doesn't talk to Babblesim, and does not need to use the Zephyr API at all.

This setup enables a faster feedback loop during development and you get full RF traffic immediately, without expensive equipment.

Using the demo

• Open a terminal in python-demo/ and run run.sh
• Open another terminal in python-demo/ and run python ble-host.py
• The scanning device logs Bluetooth advertising reports
• Stop the simulation using Ctrl-C

The packet trace will be exported to python-demo/trace.pcap and you can open it in Wireshark.

I don't want to use VSCode

No worries!

Follow the Zephyr "getting started" guide and the nrf52_bsim building guide and you should be running Babblesim locally in no time.

The only difference is the west init command: replace it with: west init -m https://github.com/jori-nordic/bsim-demo

More cool demos

You can leverage a whole bunch of native tools to debug Babblesim programs. A good one is the RR time-travelling debugger.