Among the many features built into Microchip’s Enhanced FLASH Microcontroller devices is the capa- bility of the program memory to self-program. This very useful feature has been deliberately included to give the user the ability to perform bootloading operations. Devices like the PIC18F452 are designed with a desig- nated “boot block”, a small section of protectable pro- gram memory allocated specifically for bootload firmware. This application note demonstrates a very powerful bootloader implementation for the PIC16F87XA and PIC18F families of microcontrollers. The coding for the two device families is slightly different; however, the functionality is essentially the same. The goals of this implementation stress a maximum performance and functionality, while requiring a minimum of code space. AN851 A FLASH Bootloader for PIC16 and PIC18 Devices Author: Ross M. Fosler and FIGURE 1: BOOTLOADER FUNCTIONAL Rodger Richey BLOCK DIAGRAM Microchip Technology Inc. Bootloader Firmware RX TX INTRODUCTION ……