Spark Loader is a boot loader for AVR microcontrollers, it is used for programming flash and EEPROM using a serial link between your computer and the microcontroller through any free COM port. Spark Loader consists of two parts: 1. On - chip boot loader: A hex file that resides in the boot section of the flash memory. 2. Windows application: It has the responsibility of transmitting flash and EEPROM data into the microcontroller.