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Interfacing with the Witti Dotti Bluetooth LE display device
Python C++
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README.md

README.md

Driving the Witti Dotti device via Bluetooth LE

Disclaimer:

I am not liable for any damage this may cause to your Dotti - No changes are made to the Dotti's firmware, and my experience has been that any transient problems are easily rectified by powering down the Dotti for a few minutes (as well as resetting or rebooting the Linux device that's trying to communicate with the Dotti). The official (and unoffical) apps seem to continue to work just fine regardless of all that, once you power cycle the Dotti.

I am not affiliated with Witti - I bought this (on sale!) because I figured since there's already an opensource Android app out there for it (https://github.com/bertrandmartel/dotti-bluetooth-android) that it just might be possible to make this work with the RPi2 - my bet paid off!

Video of the first (RPi) example in action!

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Arduino-ESP32

Use the latest Arduino-ESP32 from the master branch. Build the appropriate demo and load it. It runs automatically.

Raspberry Pi + Python Interfacing

The Python part of this project leverages the bluepy project to interface to the Witti Dotti device from a Linux device (e.g., the Raspberry Pi 2)

Configuration:

  • Witti Dotti (http://wittidesign.com/en/dotti/)
  • Raspberry Pi 2 running Raspbian Wheezy (with the latest updates)
  • Plugable USB Bluetooth 4.0 Low Energy Micro Adapter (model USB-BT4LE)
  • bluez (5.23-2+b1), blueman (1.99~alpha1-1+deb8u1), bluetooth (5.23-2) from Raspbian Wheezy repos
  • bluepy (https://github.com/IanHarvey/bluepy) (I used commit 04bcf93 which leverages bluez 5.29)
    • Interfaces with bluez via IPC using a helper executable

Usage:

  • Install the Bluetooth stack as above
  • Clone this repo
  • Enter the python directory
  • Clone bluepy and build it per its instructions (you can clone, build and keep bluepy wherever you prefer but you may need to modify the path to the btle module accordingly in the examples)
  • Make sure the Bluetooth daemon is running and that you can connect to your Bluetooth controller
  • Use bluetoothctl to find your device's MAC address (important!)
  • Run an example, e.g. dotti-example-1.py 5C:31:3E:00:00:01 <-- replace with your Dotti's actual MAC address
  • If all goes well, and your Bluetooth stack is running (and your adapter works with Bluetooth LE!) this should work
  • If it doesn't, ping me... I'm still learning how to communicate with this thing.

Notes

  • Writing to the Dotti is slow, and I'm bypassing the callbacks to speed it up - this works to a point, but refresh rates are really low (if you go much faster then you end up having to reboot your host as well as the Dotti to get it back to connecting).
  • The Dotti is a neat device - but it's neater still when it's on sale!
  • The internals are a TI CC2540F256 MPU for the BLE interface, a TTP234-based touch input, and an unknown driver for the 32-pin RGB LED pack. Taking one apart is a royal pain, but necessary if, like mine, one or more of the LED pack's solder joints are cold or completely disconnected.
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