No electronics project of mine ever ends without me rerouting and resoldering at least two connections.


Because many if not most sources for connector pinout info do not deal well with the fact that there are at least four ways of describing every damn type of plug/jack: looking at the front of the male-ish half, looking at its back (or at the solder lugs) and ditto for the female-ish half.

Lots of info out there lacks any label stating which of the damn choices their description uses, and I seem to be a sucker for picking the wrong interpretation or orientation or both (I'm not dyslexic at all but still don't want to remember the number of DB9s I've had to redo because I mirrored the intended connections...).

And don't get me started on the definitions of TX and RX lines: without an explanation of who the transmitting party is, the info is worthless.

This time I'm building a Sun Type 4/5 keyboard to PS/2 converter/translator, which is fun on the Sun side (simple RS-232 with inverted TTL signal levels) but really ugly on the other end (the PS/2 protocol is an extremely hideous thing to implement, but then that's IBM for you).

Yesterday's resoldering exercise came from my misinterpreting the "Keyboard Out" label in the Sun pinout to mean "to the keyboard" which - surprise! - it ain't. Still, no big deal, and with the hardware complete (a 7404, a PIC16F628, one cap and two connectors) now it's "just" a question of finishing and debugging the microprocessor code to do what it is supposed to do.

[ published on Sat 27.02.2010 13:34 | filed in interests/tinkering | ]
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© Alexander Zangerl