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[avrdude-dev] Re: avrdude-dev Digest, Vol 12, Issue 4
From: |
Lou Cypher |
Subject: |
[avrdude-dev] Re: avrdude-dev Digest, Vol 12, Issue 4 |
Date: |
Sat, 24 Jan 2004 13:21:51 +0100 |
> 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.
Don't forget that common optocouplers do have a very slow propagation time,
i.e. 4N25 and 4N35 are specified by Agilent to have a typical rise/fall time
of 3 us, and someway similar are devices like Toshiba TLP521; in this case a
1.6 us pulse gets completely lost.
A good choice could be with 6N135, 6N136 or even better 6N137, that are all
fast enough, and quite common devices.
Lou
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