As it stands it would appear that your version of the breakout board can not support UART mode.
Looking at the front side of the board, there are two solder pads, next to the XYZ axis label:
They aren't labelled, but following the guide by David Piling, they may require changing the soldering/bridging in order to change the mode. However, how the change is made, is not clear, and doesn't appear to be documented.
However, on the Arduino forums, this thread, GY-BNO055 Issues, and in particular this post, shows how to set the UART mode:
On the breakout there are two unmarked jumper pads
Some manufactures are shipping these modules with the jumpers open,
Others ship with the jumpers closed. To configure the module for i2c
communication both jumpers should be closed.
So you need to unsolder the bridge on the pads closest to the IC, to set UART mode.
Image from Don’t get the wrong BNO055!:
- the pads are soldered, then they are grounded, i.e. set to
- the pads are open, then they are equivalent to
1 (as there appear to be two pull up resistors, just below the pads, labelled
So now you can set the BNO055 to whatever mode you require by following the table: