melabs Loader - discontinued   version information

The melabs Loader is no longer available.  We will still host the Build Your Own Loader page for some time to come so that you can continue to create .HEX files for the melabs Loader.

If you would like to make your own bootloader, Microchip has a some useful application notes to help you do this. AN732 is for the PIC16F87x parts and may be modified to work with other self-programming PIC16Fxxx parts. AN851 is for both the PIC16Fxxx and PIC18Fxxxx parts. AN247 shows how to build a boot loader for PIC18Fxxxx parts that can be used on a CAN bus.

Mecanique, the creators of MicroCode Studio, also now have a stand-alone boot loader available. It can be licensed for distribution with your product.  The Mecanique boot loader is included as part of MicroCode Studio Plus. Detailed information about the MicroCode Loader can be found on Mecanique's web site.

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How It Works

The PIC16F8xx and 18Fxxx devices have a special feature not available on other PICmicro MCUs: they can program their own code space while running. All of the other PICmicro MCUs must be programmed by some kind of PICmicro MCU device programmer, like the EPIC™ Programmer. This self-programming feature allows one of these devices to run a special kind of program called a bootloader.

A bootloader is a program that resides in the code space of the target MCU. It can be activated to allow additional program code to be written to and read from that same target MCU. The melabs Loader includes such a bootloader program. The melabs Loader consists of 2 elements, connected by a serial cable.

The first part of the melabs Loader is a program resident on the PICmicro MCU. This program occupies the upper 256 words of the code space (264 words for 18Fxxx devices). This small program must be put into the PICmicro MCU using a conventional programmer, or the MCU may be purchased with this program already resident. A pre-programmed PICmicro MCU is included as part of the melabs Loader package.

The program resident on the PICmicro MCU communicates with the second element of the loader over a serial connection. This second program is a 32-bit Windows PC program that is the user interface for the loader. It allows selection of the file to be programmed, as well as has the capability to read and verify the downloaded user program on the target MCU. This is the program you see as the melabs Loader.

Only the code space and data space may be read and programmed on the target MCU. The ID space and configuration fuses are not accessible to the melabs Loader. The configuration fuses must be set at the time the actual loader program is programmed into the PICmicro MCU. Once they are set, they cannot be changed by the melabs Loader.