Issues with a bootloader

Hi,

I'm experimenting with the Tiny Bootloader (http://www.etc.ugal.ro/cchiculita/so...bootloader.htm). I've configured the loader for the PIC I'm using (18F4580) and after I've squirted the loader hex code to the PIC and the tiny boot loader PC application sees and identifies the chip. I can then load my HEX code via the Tinyloader PC app, which then runs fine on the PIC, but after doing so the tinyloader application can no longer find the PIC.

The website mentions

Quote:

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In order for the bootloader to be launched after each reset, a "goto bootloader" instruction must exist somewhere in the first 4 instructions

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I'm gathering that the process of uploading my code over writes the flash memory containing the bootloader, or the "goto" part.

can anyone comment or offer advice on what I need to do to my code in order to maintain the functionality of the bootloader.

Posting your code would undoubtedly help people to help you.

Robert

Sorry Rob,

a) the code is around 2000 lines long, and
b) I'm not ready to publish it yet.

It does write EEPROM data at 0,0 and normal data up to $80

Malc,

Do you have the DEFINE LOADER_USED 1 directive in your program?

By the way, here is link on the subject.
http://support.melabs.com/threads/77...ght=Bootloader

I meant at least the first few lines until LOADER define. :)

Malc,

After you use the boot loader to load your hex file and then the boot loader can no longer see the PIC, why don't you use you PIC programmer to read the PIC back to a file. You can the disassemble it and look at the the first 8 instructions. You might be able to see what is happening that way.

If you need help let me know.

Ok I'm missing the basics - do you have to amend the main code to include a statement to look at the bootloader ?

Here's the first few lines of the main program code as requested

Code:

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INCLUDE "Hardwr_4580.pbp"
DEFINE WRITE_INT 1                                                                                                       
INCLUDE "DT_INTS-18.bas"                        ; Base Interrupt System
include "AM2302_LIB_v024.bas"
ASM
INT_LIST  macro                                ; IntSource, Label, Type, ResetFlag?
        INT_Handler  TMR1_INT,  HeaterDrive,  ASM,  yes
       
    endm
    INT_CREATE                                  ; Creates the interrupt processor
ENDASM

T1CON = %00000001                              ; free-running, 1:1 prescaler
@  INT_ENABLE  TMR1_INT                      ; enable Timer1 interrupts

ENABLE DEBUG

;----[DS1820 Options]----Value----Default-----------------------------------
DEFINE  DS1820_DECIMALS    1                    ' 1
DEFINE  DS1820_VERIFYCRC  YES                  ' NO
DEFINE  DS18B20_ONLY      YES                  ' NO
INCLUDE "DT18x20.pbp"                          ' Include DT18x20 module

;----[Analog Settings]------------------------------------------------------
INCLUDE "alldigital.pbp"

;----[PID multi-channel]----------------------------------------------------
PID_Channels CON 4
INCLUDE "incPID_mc.pbp"                        ' Include the multi-channel PID routine.

;----[Port settings]----------------------------------------------------
TRISA = %11001111
TRISB = %00000000
TRISD = %00001111
CMCON = 7                                      ' disable Comparators
ADCON1 = $0F  ' %0000 1111 AN2=VSS, AN3=VDD, AN12-0 = Digital
ADCON2 = $00  ' %0000 0000

;----[AM2302 ]----------------------------------------------------------
AM2302_MAX_SENSORS con 4  ' Number of Sensors Used

;----[USART defines]--------------------------------------------------------
DEFINE HSER_RCSTA 90h ' Enable serial port & continuous receive
DEFINE HSER_TXSTA 24h ' Enable transmit, BRGH = 1
DEFINE HSER_CLROERR 1 ' Clear overflow automatically
DEFINE HSER_SPBRG 86  ' 115200 Baud @ SPBRGH = 0
BAUDCON.3 = 1        ' Enable 16 bit baudrate generator

RCSTA = $90  ' Enable serial port & continuous receive
TXSTA = $24  ' Enable transmit, BRGH = 1
SPBRG = 86    ' 115200 Baud @ -0.22%
SPBRGH = 0
BAUDCON.3 = 1 ' Enable 16 bit baudrate generator

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I wiped the PIC and loaded the bootloader, read back a screen dump and showed FF for all blocks apart from the 1st four. The PC app fond the pic and uploaded the main code - You can see that the first 4 blocks remained the same so I'm guessing it didn't overwrite the bootloader (see the diagram attached)

My PicFlash application has tick boxes for code protect sections of PIC memory - is it worth enabling this for 0x00 ??

http://www.micro-heli.co.uk/screendump.png

Sorry guys the forum resizes the image - here's a link to the full sized one http://www.micro-heli.co.uk/screendump.png

Scampy,
Try adding

Code:

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DEFINE LOADER_USED 1

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And see if that makes it any better.

/Henrik.

Surely a boot loader can’t be written in a few instructions...
Have you scrolled right down the bottom of your hex file when only the boot loader is loaded?
I think it would be written to the last locations it could fit.

Art, I think the bootloader contains the "goto" section at the start, and then the actual loader is at the end of the code space as shown below and confirmed in the attachment.

http://www.etc.ugal.ro/cchiculita/so...bootloader.png

@Henrik, Line added to the main code - thanks

It's still flakey, but seems to work 8 out of 10 times !

Cheers guys

If the boot loader can write your program over serial the pic must support program memory read/write.
So you should be able to check if the loader exists with your own pic program.
If you think you're overwriting it with your program you'd only need to check the first word is correct.

Code:

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pword var word
index var word

index = $7F40
LCDOUT ... clear screen and home command
READCODE index,pword
IF pword = $700E THEN
LCDOUT “  Loader exists  "
ELSE
LCDOUT “Loader Overwrite"
ENDIF

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