Re: [avr-gcc-list] programming header, pinout?

[Graham Davies]

"Richard Urwin" wrote:

> It's easy enough to find a 6-pin header with individual crimp pins. The
> 10-way pin-out gives you interleaved ground wires when wired with
> ribbon, reducing cross-talk.  So I'd say it depends on what sort of
> cable you prefer, and how long it's going to be.

I wonder at what operating frequency and cable length the interleaved
grounds become significant?  If I had to waste some wires, I'd interleave
grounds on them too, but I'm not sure one should shy away from the more
compact 6-pin layout just to get them.

> You can probably get polarised 10-pin sockets too, so it also depends on
> what sort of users you've got ;-)

Polarized / non-polarised / headers / sockets / whatever, 10-pin are easier
to find (in small quantity at least) than 6-pin.  The same for the cable
itself.  Neither Mouser nor Digi-Key have the 6-pin stuff.

> NB. The pinout has pins 1 and 2 across the width of the pinout, and odd
> numbers down one side and even numbers down the other. IIRC that's not
> the standard numbering for IDC sockets, but it does match the ribbon
> cable.

This zig-zag numbering is standard for two-row headers, probably because of
their common use with ribbon cable.  Mating IDC sockets only have pin 1
marked, so how the other pins are numbered is up to you.  Where you can get
really confused is with IDC DB9s where the pins are numbered along one row
first and then along the other.  Only pin 1 matches up end-to-end.  (Is this
the most off-topic thing to appear here, or what?)

Graham.