piclist 2003\11\10\232702a >
Thread: Bootloaders and BOOTRST
face BY : Michael Milner email (remove spam text)


I've used PICs for quite some time and I've recently started dabbling with
AVRs (I like the gcc tool chain).

I've been trying to get a bootloader to work properly on the ATmega8.  The
bootloader code works, however I'm having trouble getting the AVR to start
in the bootloader when reset.

Supposedly programming (clearing) the BOOTRST fuse will cause the
processor to start at the beginning of the bootloader section on reset
(instead of at the application code at 0x0000).  Instead, the code starts
at the application code regardless of the value of the fuse.  Are their
any tricks to this?  Am I forgetting something?

I'm using the uisp programmer under Linux.  The following shows the
current value of the fuses:

[root@lh work]# /usr/local/bin/uisp -dlpt=0x378 -dprog=dapa --rd_fuses
Atmel AVR ATmega8 is found.

Fuse Low Byte      = 0xff
Fuse High Byte     = 0xc0
Fuse Extended Byte = 0xff
Calibration Byte   = 0xa4  --  Read Only
Lock Bits          = 0xff
   BLB12 -> 1
   BLB11 -> 1
   BLB02 -> 1
   BLB01 -> 1
     LB2 -> 1
     LB1 -> 1


Anyone have any ideas?



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