## Caterina
-Arduino boards and their clones use the [Caterina bootloader](https://github.com/arduino/Arduino/tree/master/hardware/arduino/avr/bootloaders/caterina) (any keyboard built with a Pro Micro, or clone), and uses the avr109 protocol to communicate through virtual serial. Bootloaders like [A-Star](https://www.pololu.com/docs/0J61/9) are based on Caterina.
+Arduino boards and their clones use the [Caterina bootloader](https://github.com/arduino/ArduinoCore-avr/tree/master/bootloaders/caterina) (any keyboard built with a Pro Micro, or clone), and uses the avr109 protocol to communicate through virtual serial. Bootloaders like [A-Star](https://www.pololu.com/docs/0J61/9) are based on Caterina.
To ensure compatibility with the Caterina bootloader, make sure this block is present your `rules.mk`:
3. Flash a .hex file
4. Reset the device into application mode (may be done automatically)
+## USBasploader
+
+USBasploader is a bootloader developed by matrixstorm. It is used in some non-USB AVR chips such as the ATmega328P, which run V-USB.
+
+To ensure compatibility with the USBasploader bootloader, make sure this block is present in your `rules.mk`:
+
+ # Bootloader
+ # This definition is optional, and if your keyboard supports multiple bootloaders of
+ # different sizes, comment this out, and the correct address will be loaded
+ # automatically (+60). See bootloader.mk for all options.
+ BOOTLOADER = USBasp
+
+Compatible flashers:
+
+* [QMK Toolbox](https://github.com/qmk/qmk_toolbox/releases) (recommended GUI)
+* [avrdude](http://www.nongnu.org/avrdude/) with the `usbasp` programmer
+* [AVRDUDESS](https://github.com/zkemble/AVRDUDESS)
+
+Flashing sequence:
+
+1. Press the `RESET` keycode, or keep the boot pin shorted to GND while quickly shorting RST to GND
+2. Wait for the OS to detect the device
+3. Flash a .hex file
+4. Reset the device into application mode (may be done automatically)
+
## STM32
All STM32 chips come preloaded with a factory bootloader that cannot be modified nor deleted. Some STM32 chips have bootloaders that do not come with USB programming (e.g. STM32F103) but the process is still the same.