Quick Bootloader Question

[rwskinner]

I use the Mechanic Bootloader maily because it is the one I used for all my projects. I'm now going to try and use it with CCS on a 18F2580.

The instructions are here, but I'm not sure I understand the ORG instruction and how I should use it.

The bootloader software resides in the upper 256 words of program memory (336 words for 18Fxxx devices), with the rest of the microcontroller code space being available for your program. Because the loader resides in the upper part of program memory, it needs a way to 'jump' to the start of the bootloader code when power is first applied, or when the microcontroller is reset. To do this, it uses the first four program words (called the reset vector) to execute a jump to the bootloader code. When you program the target microcontroller using MicroCode Loader, program instructions that occupy the first four locations are automatically relocated by the bootloader. If the bootloader did not relocate these instructions, the important 'jump to bootloader' would get overwritten and the bootloader software would not start next time power was applied or the microcontroller was reset. Therefore, your program needs to be modified to support this process. It's a very simple change, with some examples shown below.

Assembler Programs
ORG 0x000
MOVLW 0x00
MOVWF PCLATH
GOTO StartOfProgram

ORG 0x0004
StartOfProgram
; your program goes here

For 18Fxxx(x) devices, use something like:
ORG 0x0000
GOTO StartOfProgram

ORG 0x0008
StartOfProgram
; your program goes here

[rwskinner]

After tons of reading, this is what I came up with. Can anyone confirm?

My boot loader uses the TOP 336 Words so in the top of my main program i do this.....

#org 0x7D60, 0x7FFF //32096 to 32767
#build(reset=0x1,interrupt=0x5)

Var Defs
Functions

Main ()
While ()
{
Do Something
}

[ckielstra]

If you have the bootloader in top of the memory then you don't need the #build statement, the default values are good (and yours are wrong).

Add the DEFAULT keyword to the #org statement to ensure all compiler generated functions (delay, rs232, etc) are placed in your new memory segment.

[rwskinner]

#org 0x7D60, 0x7FFF {} //32096 to 32767

I thought this told the compiler not to put anything there, since that is where the loader resides?

[ckielstra]

[rwskinner]

It states that I must reserve the upper 336 words of memory for nothing but the loader. The 4 first four bytes need to be relocated in my application.

I tried what I had and it seems to work, but since I'm sending out 300 of these devices I can't afford any gotchas.

The Loader is "microcode mcloader"

http://www.mecanique.co.uk/code-studio/loader/index.html

So this is what I put in my programs header file....

[rwskinner]

[quote="ckielstra"]