How to transfer files over BLE

Image from Wikipedia

I’ve now taught a lot of workshops on TinyML using the Arduino Nano Sense BLE 33 board, including the new EdX course, and while it’s a fantastic piece of technology I often have to spend a lot of time helping students figure out how to get the boards communicating with their computer. Flashing programs to the Arduino relies on having a USB connection that can use the UART serial protocol to communicate, and it turns out that there are a lot of things that can go wrong in this process. Even worse, it’s very hard to debug what’s going wrong, since the UART drivers are deep in the operating system, and vary across Windows, MacOS, and Linux computers. Students can end up getting very frustrated, even after referring to the great troubleshooting FAQ that Brian on the EdX course put together.

I’ve been trying to figure out if there’s an alternative to this approach that will make life easier. To help with that, I’ve been experimenting with how I might be able to transfer files wirelessly over the Bluetooth Low Energy protocol that the Arduino board supports, and I now have a prototype available at github.com/petewarden/ble_file_transfer. There are lots of disclaimers; it’s only a few kilobytes per second, I haven’t tested it very heavily, and it’s just a proof of concept, but I’m hoping to be able to use this to try out some approaches that will help students get started without the UART road bumps.

I also wanted to share a complete example of how to do this kind of file transfer more generally, since when I went looking for similar solutions I saw a lot of questions about how to do this but not many solutions. It’s definitely not an application that BLE is designed for, but it does seem possible to do at least. Hopefully having a version using a well-known board and WebBLE will help someone else out in the future!

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