keypad over one wire

[blueroomelectronics]

Issue #2 of JPUG has a 1 wire analog type schematic and source for the 18F1320 (Junebug)

 

[arhi]

Issue #2 of JPUG has a 1 wire analog type schematic and source for the 18F1320 (Junebug)

I need the smiley banging the head to the wall .... I knew I saw that somewhere .. I knew it ... but .. could of saved me few hours

EDIT: just checked it out ... this one would not do it .. the schematic from the jpub is to "make the keypad" and you use resistor per key ... if you get the standard keypad (factory one) you cannot put the resistors without doing too many modifications ... the one I needed / made is attachable to any off the shelve keypad 3x4 (easy to modify to 4x4)

 

[shingadaddy]

It is fairly common. Heres another similar version. I've interfaced to a piece of avionics equipment that ran variable resistors and switches using the resistance method to the input of an analog multiplexor. The reading device supplied a clock and one wire. The clock drove a counter and every so many counts, a new analog value was place on the multiplexor output (single wire)for reading the level or state, by an analog input on the micro. Works like a charm

Multiple buttons, no problem.