AVR-Chat

12 grudnia 2004, 18:27

I've simple spi programmer. I've successfuly programmed mcu (atmega8)
several times (about 20), but today I had to change something in it and I've
accidently changed MISO and MOSI lines. I've tried to write the
mcu but of course it didn't work. I've found the mistake and I've
changed the lines back, however I can't write flash now.

I can read the flash and it contains good, and working code which was
written to the mcu before modifications made to spi programmer. I'm
also able to read the signature, lock and fuse settings, so I know that
the lock bits aren't set.

When I'm trying to write something (flash, eprom, fuse bits) the mcu
hangs and there is verification error at address 0. After that any
read from mcu returns 0xff (for example when I want to read signature)

Maybe someone had same or similar problem? Do You think that changeing
MISO and MOSI could damage the mcu?

-- 
beaver

JID: bvr@jabber.org

I am experiencing a similar problem My currently loaded program uses
portb pin 0 SS and so it is setting this improperly and causing me not
to be able to program the board.

I posted a question somewhere else. Hopefully someone will have an
answer.

-----Original Message-----
From: beaver [mailto:bvr@o2.pl] 
Sent: Sunday, December 12, 2004 12:56 PM
To: AVR-Chat@yahoogroups.com
Subject: [AVR-Chat] SPI programmer problem



12 grudnia 2004, 18:27

I've simple spi programmer. I've successfuly programmed mcu (atmega8)
several times (about 20), but today I had to change something in it and
I've accidently changed MISO and MOSI lines. I've tried to write the mcu
but of course it didn't work. I've found the mistake and I've changed
the lines back, however I can't write flash now.

I can read the flash and it contains good, and working code which was
written to the mcu before modifications made to spi programmer. I'm also
able to read the signature, lock and fuse settings, so I know that the
lock bits aren't set.

When I'm trying to write something (flash, eprom, fuse bits) the mcu
hangs and there is verification error at address 0. After that any read
from mcu returns 0xff (for example when I want to read signature)

Maybe someone had same or similar problem? Do You think that changeing
MISO and MOSI could damage the mcu?

-- 
beaver

JID: bvr@jabber.org





 
Yahoo! Groups Links

The reading and writing processes are similar in terms of the hardware
requirements on the SPI bus.  If you can read from the chip, you had to be
able to write from the programmer's MOSI to the targets MOSI, and you had to
be able to read from the target's MISO to the programmer's MISO.  The same
process is involved in writing to the target, just a difference in the bytes
on the wire.  I suppose there could be hardware damage depending on your spi
programmer design, but if you're reading valid data, I'd assume that the SPI
bus is still functional.

hth,

Tony

----- Original Message -----
From: "beaver" <bvr@o2.pl>
To: <AVR-Chat@yahoogroups.com>
Sent: Sunday, December 12, 2004 11:56 AM
Subject: [AVR-Chat] SPI programmer problem


>
> 12 grudnia 2004, 18:27
>
> I've simple spi programmer. I've successfuly programmed mcu (atmega8)
> several times (about 20), but today I had to change something in it and
I've

> accidently changed MISO and MOSI lines. I've tried to write the
> mcu but of course it didn't work. I've found the mistake and I've
> changed the lines back, however I can't write flash now.
>
> I can read the flash and it contains good, and working code which was
> written to the mcu before modifications made to spi programmer. I'm
> also able to read the signature, lock and fuse settings, so I know that
> the lock bits aren't set.
>
> When I'm trying to write something (flash, eprom, fuse bits) the mcu
> hangs and there is verification error at address 0. After that any
> read from mcu returns 0xff (for example when I want to read signature)
>
> Maybe someone had same or similar problem? Do You think that changeing
> MISO and MOSI could damage the mcu?
>
> --
> beaver
>
> JID: bvr@jabber.org
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>
>