I am in very big confusion, about usb bootloader , how usb bootloader update firmware, could you please describe the usb bootloader and how command prompt is used for this action.
Hang on my dude. You are going from 0 to a 100 real fast. You must crawl before you walk. You got some prerequisite. I will cover all of this in due time including creating a bootloader. - Must be able to read and wire to the flash - Understand your flash layout - Understand how to setup your flash in the linker - Understand your build outputs files - Get a simple application jump working - Understand how to read an write binary files from a PC - Understand the interface you are going to use. It can be USB, UART, I2C, SPI etc. Does not matter what the interface is all you want to do is stream the application binary file to the bootloader. I would recommend not using USB. It will eat up your flash memory and it is a total bitch to work with. UART will be the least painful.