Created: 2011-07-16 07:47
Updated: 2013-11-03 20:35


PICBoot Bootloader

Alpha Release

The PICBoot bootloader is currently in a working state and can reprogram a PIC18F27J53 microcontroller from a hex file on a FAT-formatted SD card. It is definitely alpha software and has only been through a few rudimentary tests. An example application is included in the example folder that illustrates how to set up an application to use the bootloader.


Once programmed onto the target microcontroller the bootloader uses the state of a switch at startup to determine whether to enter bootload mode or run the main application. In bootload mode it will look for a file on the root of the attached SD card for a file called platform.hex. There is currently very little error checking and there is room for a lot of improvements but it is functional. If you have the inclination to contribute I'd certainly welcome any enhancements to the code.

Features and Future Enhancement

The current features of the PICBoot bootloader are few and far between:

  • Reads raw hex file produced by IDE.
  • Doesn't require any software or connection to a computer to program (field reprogrammable)
  • Implements a simple code protection mechanism to prevent user applications from overwriting the bootloader

Here is my current wish list for enhancements and future capabilities:

  • Implement buffered reading of hex files. Reading hex files 1 byte at a time has a major speed impact.
  • Optimize and shorten the convert_hex_digit function in hexreader.c
  • Implement software flag to indicate mode instead of the switch state
  • Replace Petit FatFS with FatFS to unlock more file options
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