AN247 Datasheet | Microchip Technology

features built into Microchip’s Enhanced FLASH Microcontroller devices is the capability 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 PIC18F458 are designed with a designated “boot block”, a small section of protectable program memory allocated specifically for bootload firmware. This application note demonstrates a simple bootloader implementation for the PIC18F families of micro Programming a Running System controllers with a CAN module. The goals of this implementation are to stress maximum performance An interesting situation is bootloading in an active and and functionality, while requiring a minimum of code functioning system. In this instance, one or more of the space. For users developing CAN enabled systems, it nodes are taken off-line to update their firmware, yet provides a low level framework that can be used .. with the functionality of the entire system is not pletely higher level network protocols to develop more disabled. This, of course, requires that the target node plex and custom-tailored systems. or nodes have some functional independence from CONSIDERATIONS FOR FIELD PROGRAMMING OVER THE CAN BUS The bination of FLASH technology and robust network munication capability in a single device makes over-the-network programmability a very desirable option. However, this makes bootloading on a CAN bus network a very different challenge from more typical uses, such as using a bootloader to program a single FLASH device in isolation. Let’s consider some of the key issues in over-the-network programming. other parts of the networked system. There are priority issues to contend with when programming in an active system. For example, what priority can be given to the bootloader without affecting the critical munications in the system? If higher priority is given to nodes running the bootloader than other nodes running their...