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| From: | Trampas |
| Subject: | RE: [avr-gcc-list] AT90CAN128 bootloader |
| Date: | Sat, 25 Nov 2006 13:11:13 -0500 |
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Larry, I have some stupid questions. Does the
AVRDUDE and/or AVR Studio send out “0 “ to start programming? Is
there some specification somewhere? What happens if user does hit “0 “
by accident? I would very much like to do two things,
one is have the automatic bootloader like you do, and the second is to integrate
the bootloader into my code, thus I assume there are some special linker stuff
I need to do? Thanks again for the help. Thanks Trampas From: Larry Barello [mailto:address@hidden Thanks! IIRC you can cut out the EEPROM support
and the boot loader fits into 256 words… While paring down the size I cut out the C
startup (there is no “main()”) & runtime support and moved
statics/globals into automatics assuming they would go onto the stack.
However that clever compiler kept everything in registers and the resulting
code generation was spectacular. One thing not mentioned in the README is
if your application scans for 0x30, 0x20 (no echo) and then “jumps”
to the bootloader + one instruction, you can have entry into the loader
automatic. I do that with all my projects (that have user interfaces)
with a tiny state machine that eats the two characters (printing them if it
fails). That way I don’t have to reset or otherwise fool around:
Just run AvrDude and tada! new code in 10 seconds or less. “0
“ is an unusual sequence so I never trip across it otherwise. Cheers! Nice work! Compiled
with avr-gcc 3.4.6 it uses just 418 instructions out of 512 and it works with
"avrdude"! -- Bruce D. Lightner Lightner Engineering Voice: +1-858-551-4011 FAX: +1-858-551-0777 Email: address@hidden URL: http://www.lightner.net/lightner/bruce/ |
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