Re: [avrdude-dev] Problems reading writing fuses to at90s1200 with stk500

[Klaus Rudolph]

Jan-Hinnerk Reichert wrote:
> 
> Hi Klaus,
> 
> avrdude only supports SPI-programming.
> 
> According to the datasheet the AT90S1200 has only a SPI-command for
> setting lock-bits. All other operations on lock- or fuse-bits are not
> supported.
> 
> The only bug seems to be that the config-file defines commands for
> these actions. Either they are from an outdated datasheet or (more
> likely) copied from another chip definition.
> 
Seems to be a much bigger problem here...

As I looked a bit inside the code the fuse bits will be read out with
the
universal command what is not possible with actual firmware I think.
Instead the commands 0x72 (ReadFuseBit) 0x77 (ReadFuseBitsExt) and 0x73
(ReasdLockBits)
should be used. 

I have changed the SPI to parallel programming in the setup, but this is
not enough.
I changed all needed things a year ago in uisp and this works but after
2 hours of digging
through avrdude I´m not found all what I searched for :-(
. 

As I think after 2 hour of code inspection there is a
avr_read_byte_default function which
uses for stk500 the stk500_cmd function which is not correct for fuses I
think. Also for at90s1200
the function readLockBits (0x73) must be used to read fuse bits. (This
info comes from tracing
avr-studio and reading the AVR061 document).

OK. I will stop here today. If someone here is able to tell me if my
ideas here right or not I maybe will able
to put in a real stk500 support :-). Currently it is not enough for me. 

Additional an other error was found. The command 0x45 needs 4 bytes info
and not 5! The code
holds an n_params+1 line. Thats not correct as I look inside the
avrstudio trace for that.
Currently it doesn´t matter but for future firmware?

Thanks
        Klaus