http://www.microchip.com/SWLibraryWeb/p ... nd+dsPIC33
Microchip Easy Bootloader for PIC24 and dsPIC33
The Microchip Easy Bootloader for PIC24 and dsPIC33, or EZBL for short, is a library of software components and example projects designed to facilitate creation of Bootloaders and compatible Applications. It aims to simultaneously support a wide range of target PIC® MCU and dsPIC® DSC processors, minimize implementation effort/design time and maintain sufficient flexibility to accommodate many different communications protocols and bootloading topologies. Using build-time automation tools and efficient run-time heuristics, numerous manual code changes and bootloader restrictions are eliminated as compared to historical bootloader App Notes and Code Examples.