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Re: [Uisp-dev] Re: [avr-gcc-list] uisp and new STK500 firmware?

From: Theodore A. Roth
Subject: Re: [Uisp-dev] Re: [avr-gcc-list] uisp and new STK500 firmware?
Date: Sun, 19 Jan 2003 23:07:35 -0800 (PST)

On Sat, 18 Jan 2003, Patrick Mahoney wrote:

:)Hello pple,
:)Is it possible to go back earlier firmware after having upgraded to
:)1.41? If so, how?

Yes. I just did this to downgrade my stk500 from 1.41 to 1.7.

(If I know how to convert a .ebn file to .hex or .srec you could you uisp to 
"upgrade" the stk500 firmware. More on this later. ;-)

- Install AvrStudio 3.53
- Turn on the stk500 while hold the "Program" button (or short the jumper 
next to it).
- start avr studio, run "AVR Prog" from the tools menu (not the skt500 
- perform a chip erase
- exit avr studio
- find the upgrade.exe program which came with avr studio 3.53 and run it

If all goes well, you will have firmware version 1.7 in your stk500 now.

Note the you have just upgrade the program in the 8535 in the stk500. 

There's also a at90s1200 on the stk500 which has a 6-pin isp connector next 
to it. I was able to dump the firmware from the 1200 and after analyzing the 
disassemble of the program now know what the 1200 does. On a normal power up 
of the stk500, the 1200 just goes to sleep, but when holding down the 
"program" button (or jumpering it), it starts up an immediately pulls the 
8535's reset line low and then takes over the rs232 ctrl port. At that point 
is basically acts just like a "AVR ISP" type programmer. This is why avr 
studio can talk to it when you use the AVR Prog tool instead of the stk500 

Since uisp knows how to talk to a "AVR ISP" type programmer, we could use 
uisp to update the firmware of the stk500. We just need to figure how to 
read a .ebn file. ;-)

I've also hacked the firmware of the 1200 in the stk500 to allow me to 
upgrade the firmware using avr studio, but when avr studio tries to set the 
lock bits on the 8535, my hacked firmware ignores the command. Thus, I've 
been able to do a rom dump of the 8535 and may have a rather silly way to 
convert a .ebn file to what ever format I want.

The goal of all this jiggery-pokery is figure out how the stk500 works 
internally so I can write my own (open source) firmware for it. Since Atmel 
was so kind to give us the stk500 protocol on the eve of changing the 
protocol (the jokes on us), it's time to just eliminate them from the loop. 
Such a shame that the stk500 is such a versatile piece of hardware that they 
couldn't just tell us how the freaking thing works. I really thought that 
Atmel was in the business of selling silicon, not developer kits and IDE's.

Sorry for the rant.

Ted Roth

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