Open source PBP bootloader

[pedja089]

I need to create bootloader for PIC18F that program flash from external I2C memory, eg 24lc512.
I'll probably write bootloader in pbp and asm.

If I understand correctly how bootloader works, there is 2 ways to implement bootloader.
-One is to make bootloader that sits on beginning of flash, then on address 4 and 8, need to be GOTO to new int vector. That will add one more GOTO before executing int, PBP already add one. I don't like that GOTO's.
-Other option is that first instruction in flash is GOTO Bootloader, and to put bootloader on end of flash. Then there is no need to remap interrupt. When bootloader finish job, then GOTO 1
In main program only need to remap reset vector to 1.
Am I understand how it works?

For now I'll create LED blink program, that use bootloader with reset vector at 1.
And then try to make bootloader that will program that hex to flash. For start hex will be in LOOKUP2, until I get flesh erase and write to work, then comunication...

Probably I should start with analyzing syntax of hex file.

Is there anyone interested and willing to help?

[pedja089]

Edit timeout...
Address for int are 8 and 24, and GOTO takes 2 program word so, reset org should be 4.

[pedja089]

Is there way to move RESET_ORG to other address, without moving interrupt vector?
DEFINE RESET_ORG 004h also move vectors. In .LST file interrupt vector are defined as RESET_ORG+8h or 18h.
DEFINE LOADER_USED 1 doesn't do anything. I'm looking in disassembled hex file...
This is test code:

    DEFINE NO_CLRWDT 1
    DEFINE LOADER_USED 1
    DEFINE INTHAND myint    ' Define interrupt handler
    DEFINE INTLHAND myint    ' Define interrupt handler

Start:
    PORTD.6=1
    PORTD.6=0
GOTO Start

@myint bcf PORTB,1

Also I noticed that with or without NO_CLRWDT 1, there is no CLRWDT in hex file.

[Demon]

I have VERY limitted knowledge in this area, but can't you set config fuses from the programmer?

(NO_CLRWDT is a config fuse right?)

If input to the programmer is the hex file, wouldn't that mean that fuses are handled separately than the hex file?

Robert

[pedja089]

PBP should put CLRWDT if there is no defined NO_CLRWDT 1. DEFINE NO_CLRWDT 1 isn't config, it is PBP's define.

[pedja089]

This is exactly what I'm trying to do.

[Heckler]

wayneandlayne.com have a pretty neat solution for a bootloader, it uses two LED's as light detectors to receive the code that is "flashed" or "blinked" to your PC's monitor screen. One LED light sensor is for clocking and one LED light sensor is for the data.


I'm not sure if this is actually a boot loader... or more of just a way of changing the message that this little kit displays...
but I would think it could be modified to act as a boot loader.

It may even work from a smart phones browser (it does play from a phones browser)



Here is their actual programming web page where you can scroll down and click on the "GO" button and see it in action.
http://www.wayneandlayne.com/blinky_programmer/


and a description of their bootloader...
http://www.wayneandlayne.com/project...ign/#questions

Their project is open source but I'm not sure if the programming web page code is available.