Re: [avrdude-dev] may be timing problems

[Jan-Hinnerk Reichert]

On Friday 23 January 2004 20:03, address@hidden wrote:
> Hallo
> i build a optical isolated bsd programmer.
> my little tiny26 ansering and i can see the signals at pin 10 of
> lpt. is there any option for avrdude to slow down the timing of the
> signals. may be its an timing problem.
> excuse my horrible english,
> ciao axel

Your english is good enough. Nevertheless, starting sentences with 
capital letters should improve readability ;-)

There is neither a commandline- nor a config-option for setting the 
SPI-speed. SPI is running at maximum speed, which is determined by 
the time needed for an "out" or "in" instruction. That is more than 
1.6us for changing a port-bit, IIRC, which is usually slow enough.

If you are able to compile avrdude from sources, you can add delays in 
"ppi.c". If you can't figure out where, I'm willing to help.

However, you should rule out some other possibilities first:

How does your optical isolation work?
- are the optocouplers driven by a low level= ->signals get negated
- are they driven by a high level? ->not enough current
- do you have pull-ups after the optocoupler? If yes, are they strong 
enough? (I would suggest 4k7 at most)

/Jan-Hinnerk