Tiny Bootloader

Does the bootloader needs to know where the application is programmed? (at what address)

-------- Origineel bericht --------

Greetings

First: You don't download _TO_ something. you upload _TO_ a device ! (I really couldn't help it :-) )

Second : Have you made sure that you application program starts at the same address as the booloader jumps to when it does not receive a char from the PC ?

/RaceMouse

You'd have no idea how many arguments I've had about this. I agree with what you just said, but I've never been able to convince anyone else of this. It is common parlance that programming a chip is "downloading to" that chip.

My best quess is that your PIC progam should start with something like "ORG 0x100" or whatever the "jump-to-application-address" is.

/RaceMouse

As long as you agree with me you're doing fine :-)

The only way to change this "common parlance" is to use the correct terms. Agree ?

-maybe the discussion belongs in an other thread but ...

/RaceMouse

Thanks for the response.

Firstly, my background is in PLC's and the various pieces of software I use 'download to the PLC' or 'upload from the PLC'

Secondly, the bootloader I'm trying to should move the 'goto' instruction that you need to put in the first four lines of code to the start of the bootloader code. This leaves the start of memory as the bootloader set it, i.e. jump to the bootloader routine. After it has executed the bootloader routine, it jumps to just before the bootloader and should find the address of where to go next, i.e. the 'goto' instruction in my code. If you look at the web address of my initial query there is a nice picture showing what I've just tried to explain.

The download program that is on that website must modify the hex file, find the 'goto' instruction in the first four lines and overwrite that line of the bootloader.

I can't think how to test it though, has anyone else used a bootloader successfully?

John

RaceMouse wrote:

Hmmm...

Can you post the souce code of you application ?

/RaceMouse

How do I post my code, I can't see of a way to upload a file. The start of my code is as follows though.

ORG 0x00 ; Start of the program CLRF STATUS MOVLW 0x00 MOVWF PCLATH GOTO INIT

ORG 0x04 ; Interrupt address GOTO INT_HAND

All I'm doing after it goes to the INIT routine is set all the outputs on for PortA and B. I've simulated this and it works fine.

John

RaceMouse wrote:

Ok. It seems to me that you have 5 instructions within the first four program counts. Your Interrupt vector starts at 0x04 but your startup code ends at 0x05.

My suggestion: ORG 0x00 ; Start of the program CLRF STATUS CLRF PCLATH GOTO INIT

Please report back.

/RaceMouse

I tried that already but with no success. The code I showed you is straight from an example that came with the bootloader.

RaceMouse wrote:

Are you linking your application code for the correct address? The memory map should comply with the bootloader requirements.

I believe I am, I've started my program as it states in the documentation but it doesn't seem to get that far.

Pietje Bell wrote:

Can you merge the two hex files (the bootloader and you application) and run it in a simulator ?

/RaceMouse

And I just saw I was wrong 'cause "ORG" is a directive. Not an instruction :-)

/RaceMouse

No, you must start with a long jump !!

The Tiny bootloader is working perfectly, I used it for many PIC types, and it always worked perfect.

And how to program a long jump,... ... sorry I don't know, JAL is doing it for me ;-)

And if you also don't know how to program a long jump, you should really take a look at some High Level Language (JAL perhaps).

For the other discussion, I fully agree, that's why I called my program UPD (Uploader Programmer Debugger) ;-)

cheers, Stef