To jump to the bootloader, hold down "Button 4" (immediate right of the trackball)
See the [build environment setup](https://docs.qmk.fm/#/getting_started_build_tools) and the [make instructions](https://docs.qmk.fm/#/getting_started_make_guide) for more information. Brand new to QMK? Start with our [Complete Newbs Guide](https://docs.qmk.fm/#/newbs).
While the defaults are designed so that it can be plugged in and used right away, there are a number of things that you may want to change. Such as adding DPI control, or to use the ball to scroll while holding a button. To allow for this sort of control, there is a callback for both the scroll wheel and the mouse censor.
Additionally, you can change the DPI/CPI or speed of the trackball by calling `pmw_set_cpi` at any time. Additionally, there is a `DPI_CONFIG` macro that will cycle through an array of options for the DPI. This is set to 1200, 1600, and 2400, but can be changed. 1600 is also set to the default.
To configure/set your own array, there are two defines to use, `PLOOPY_DPI_OPTIONS` to set the array, and `PLOOPY_DPI_DEFAULT`.
```c
#define PLOOPY_DPI_OPTIONS { 1200, 1600, 2400 }
#define PLOOPY_DPI_DEFAULT 1
```
The `PLOOPY_DPI_OPTIONS` array sets the values that you want to be able to cycle through, and the order they are in. The "default" define lets the firmware know which of these options is the default and should be loaded by default.
The `DPI_CONFIG` macro will cycle through the values in the array, each time you hit it. And it stores this value in persistent memory, so it will load it the next time the device powers up.