At89C51RD2 ISP Programming

Hello all,

I'm using the at89C51RD2 in an current application where I;m trying to
use the Flip and the RS232 ISP programming.  I programmed a virgin chip
perfectly the first time and was amazed at how easy it was.  Now that
I'm trying to program it again though I'm having problems.  The flip
software is giving me an error message about a software timeout.

I've done nothing with ALE
I've tied EA high
and I use switches to give me the correct orientations on RESET and
PSEN.

I release my reset switch first.. and then I release my PSEN switch.


Any suggestions as to what I might be doing wrong are greatly
appreciated. 

Thanks.

<hb@viatechnology.com> skrev i en meddelelse
news:1162568572.078259.39380@f16g2000cwb.googlegroups.com...
> Hello all,
>
> I'm using the at89C51RD2 in an current application where I;m trying to
> use the Flip and the RS232 ISP programming.  I programmed a virgin chip
> perfectly the first time and was amazed at how easy it was.  Now that
> I'm trying to program it again though I'm having problems.  The flip
> software is giving me an error message about a software timeout.
>
> I've done nothing with ALE
> I've tied EA high
> and I use switches to give me the correct orientations on RESET and
> PSEN.
>
> I release my reset switch first.. and then I release my PSEN switch.
>
>
> Any suggestions as to what I might be doing wrong are greatly
> appreciated.
>
> Thanks.
>

Remember that the EA and PSEN signals are evaluated on the falling edge of
the RESET pin. So if your reset switch pulls the RESET signal low, PSEN must
be valid upon activation, not release.
Also note that upon completion of the RESET condition, the PSEN signal is
outputpin and therefore care should be taken to release this pin then reset
goes high again.
The virgin chips always start at the bootloader, so therefore this will work
regardless of your switches.

Hope this helps

Best regards
Henrik