AVR-Chat

Hello, David.

_ANSWER_EMBEDDED_

You wrote:
>  On Feb 13, 2005, at 1:16 PM, Valerij Avrealij wrote:

 >> Hello.
 >>
 >>  Some words about 7805,ISP and my AVR.
 >>  First of all my programmer works fine with mega8 and 7805,

>  Thats nice but we still don't know much about "your" circuit. The 
>  reason you are having problems is that something is different. Is this
>  board of your design?
> Is everything identical, same hardware, but for the exchange of Atmega8 and tiny15/90s2343?
The problem with tiny15/90s2343 exists when I use any hardware logic.
There are NO problems with mega8, even if I use 7805. So, it is not
a 7805-problem.

 >>  but when I
 >>  connect my ISP to tiny15 or 90s2343 also powered from 7805 or from
 >>  another source (for example, power supply (AC 220V -> DC 5V)) the 
 >>  current is very high.

>  Once again is it the exact same board or just same regulator P/N?
Yes.
> If two 5 volt regulators are connected in parallel (the one on your board
>  and the one in your ISP) then its very unlikely they both agree on the
>  same value of "5.0 volts".
No, I have just ONE power regulator on my board. The ISP is powered
from target (I using Altera ByteBlaster).

 >>  Also very interest situation is that, when I connected swiched ON ISP
 >>  to the board all are OK, but if I connected ISP with breaked VCC to
 >>  the board (but board VCC is not breaked (it is swiched ON)), and than
 >>  turn on the ISP I have very high current.

>  I don't understand the term "breaked VCC" in the above context. Am lost
>  as to the difference between "breaked" and "switched." Am guessing you
>  powered the circuit, then powered the ISP, and found high current.
No, I realy mean that VCC line is "breaked" or "disconnected". The ISP
is not self-powered, it powered from the board. When I connect VCC
line I have very high current.
But, if I connect all wires (VCC, GND, MISO,...) at one time the
current is normal.

>  my previous suggestion to put a diode immediately after the 7805
>  regulator before 5 volts reaches either the AVR or ISP header.
Even I use another power source (i.e. AC-DC convertor from 220V to 5V)
I have some problem.

By taking all described above into consideration I think that it isn't
7805-problem.

Thanks for suggestions!

-- 

  Valerij Avrealij