Improved WT12 Bluetooth UART GPIO Breakout

Improved WT12 Bluetooth UART GPIO Breakout

While working on the iWRAP code library for the Bluegiga WT12, one of the issues I’ve come across is trying to create a good way to detect and manage active Bluetooth links. The iWRAP firmware, controllable entirely over a simple UART connection, has three different possible modes. As I mentioned in my last post about the Keyglove Kit board, the most efficient solution is to avoid the high-demand MUX mode and instead rely on regular DATA/COMMAND mode switching and active link detection using two GPIO pins.

The previous revision of the WT12 UART breakout board that I created only had the basic UART pins, power pins, and the RESET pin (which I have never actually used in any of my projects, leaving me to wonder at its usefulness). I have now created a new version of that breakout board (up for purchase on InMojo) that includes two broken-out GPIO pins to solve precisely the problem mentioned above.

Notice the placement of the extra pins; they are positioned exactly 0.3″ apart from the main 6-pin UART header (which itself is pin-compatible with SparkFun’s BlueSMiRF boards). This spacing and the horizontal alignment mean this module can if desired be placed across the center of a typical solderless breadboard to allow easy access to all of the pins at the same time.

The iWRAP code that I’m working on relies on the ability to determine links status and to control mode switching programmatically for the simplest and most efficient operation. This new PCB revision should therefore help me wrap up the code and finish the keyglove’s Bluetooth integration.

Also, now that Bluegiga has just publicly released their more flexible iWRAP5 beta firmware with full documentation, I should be able to wrap up the customized HID implementation to allow mouse scrolling and few other features that were missing from iWRAP4.

Leave a Reply