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PICList Thread
'[PIC] Problem with 18F2620 and Tiny Bootlader'
2006\01\13@073600 by Pavel Kořenský

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Hello,

I have a strange problem with PIC18F260 and Tiny Bootloader 1.19

It is the first time, when I am trying to use this bootloader. I set the
xtal value and oscillator type in Tiny bootloader source, recompiled the
bootloader, programmed it into PIC with my programmer.

I tried the first download to the PIC via the bootloader and everything
was OK, without any problem.

I tried to download the program once more and it is not possible. I
tried it several times, but there was no communication between PIC and
PC program. So, I took the PIC back to the programmer, I read the
content of the flash, imported the .HEX image to MPLAB and I found a
strange error.

Inside the memory is my program at the correct address, the bootloader
is also at his place on the end of the memory. But at the address 0x0000
there is instruction GOTO 0xFE00 and it is wrong, because the correct
start address of the bootloader is 0xFF40.

I tried it once more. I erased the chip, programmed the bootloader,
verified that there is a proper GOTO 0xFF40 instruction at the start. I
downloaded my program via bootloader without problem. But no further
download is possible. I examined the content of the memory and there is
the same error. The first instruction is rewritten to GOTO 0xFE00 !!!

When the program jumps at the address 0xFE00, there are NOPs and at the
beginning of the bootloader area, there is saved the first instruction
from my program (GOTO Start). So, after the first download, the
bootloader cannot be executed again.

Anyone saw this behavior ? Any idea what can be wrong ?

I tried to send mail to the author, but I did not received any answer.


Than you for any help.



PavelK

2006\01\13@084249 by olin piclist

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"Pavel Korenský" wrote:
> I tried it once more. I erased the chip, programmed the bootloader,
> verified that there is a proper GOTO 0xFF40 instruction at the start. I
> downloaded my program via bootloader without problem. But no further
> download is possible. I examined the content of the memory and there is
> the same error. The first instruction is rewritten to GOTO 0xFE00 !!!

The symptom seems pretty clear.  There is a bug in the bootloader where it
allows the reset vector to be overwritten.


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consultant in 2004 program year.  http://www.embedinc.com/products

2006\01\13@085706 by Pavel Kořenský

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Hmm, I cannot find any bug in the PIC part of the bootloader. It seems
that the problem must be on the PC side.
It is strange that no-one reported this kind of bug. I tried to search
Piclist messages, Internet etc. and there is no mention about a bug of
such kind.


Best regards

PavelK

> {Original Message removed}

2006\01\13@090535 by Xiaofan Chen

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On 1/13/06, Pavel Koøenský <spam_OUTpavel.korenskyTakeThisOuTspamdator3.cz> wrote:> Hmm, I cannot find any bug in the PIC part of the bootloader. It seems> that the problem must be on the PC side.>> It is strange that no-one reported this kind of bug. I tried to search> Piclist messages, Internet etc. and there is no mention about a bug of> such kind.>
I think this may be because that not many people are usingtiny bootloader. ;-)
The other thing is that PIClist does not discuss 18F MCUs anddsPICs much as well.
Regards,Xiaofan

2006\01\13@091228 by Pavel Kořenský

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What other bootloader can be used for 18F2620 ?

I tried to find some other, but without success. And I do not want to
start "Yet another bootloader" :-(


Regards PavelK

> {Original Message removed}

2006\01\13@180830 by Gavin Jacobs

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FYI
I am using the Tiny Bootloader on 18f6621 successfully. My development
environment is Microchip C18 (Student version) and MPLAB.

Jake


On 1/13/06, Pavel Koøenský <.....pavel.korenskyKILLspamspam@spam@dator3.cz> wrote:
>
> What other bootloader can be used for 18F2620 ?
>
>

2006\01\13@185311 by Pavel Kořenský

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Hmmm, it seems that there must be some bug in the PC part of the Tiny
bootloader, which is specific for 18F2620 (maybe also for 18F4620).

Maybe I should try to set-up the processor type to 18F6620. The flash
size is the same and I suppose that the rest of flash writing is the
same too.
After all, at the PIC side of the bootloader, there is nothing fancy.
PIC is just copying the data from UART to the flash in 64bytes blocks.


Regards PavelK

> {Original Message removed}

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