Re[2]: [avr-chat] "Proper" programmer for Linux ?

[Kreyl]

  Hi!

You wrote:

>>   I  never  did  something  special  to make work all of this. AvrDude
>> works quite fine.

> I was only talking about the buffer used on the Ponyprog itself,
> the 74HC244 chip ;-)

  Well,  I  didn't  look  the  page  closely.  There are only parralel
variants, I use serial one (see http://www.lancos.com/siprogsch.html).
More,  I  simplified it: I never needed external power, so J9, Q6, Q4,
R15, R11, R8, and JP2 has gone. 2 and 3 of JP2 just crossed.

>>   But   surely,  to  use  ISP,  you  should  consider  some  rules  of
>> schematics.  For  example,  I can't program chip, when it connected to
>> MOSFET with great gate capacity. Powerful LED also will do ;-)

> Oops, I am not sure I understand... you mean that programming fails if
> the AVR drives an LED on one of its (ISP un-related) pins ?

  Yes,  but  this depends on LED. Really, what current your programmer
can  provide? No more than 10-15 mA. If your LED consumes more - well,
LED wil blink, chip will fail.

  I  have  no  problems  with LED in series with 100 Ohm resistor, but
direct connection would fail programming.

  Also, large MOSFETs have great capacitance of gate, so great current
needed  to recharge it during programming. It's ok with 2N7002 (50pF),
but something with 400 pF and more would probably fail.

Best regards,
                        Kreyl