Did I break it...?

Hyblademin

While trying to configure a push-button circuit, I noticed I couldn't get the button to pass a voltage. Rather, it always did, even when it wasn't pressed.

I later found out the pins 15 and 14 set as inputs on my stamp were always receiving high, even when disconnected, and wiggling nearby components made them behave erratically (rapidly alternating reception of high and low signals). I suspect that Vin may have been accidentally connected to pin 15 while building a circuit, causing damage to the stamp. I'm not sure, however, if 6V rather than 5V in an input would be enough to do this. All other pins work as normal. It seems broken enough regardless, though. Will I need a replacement stamp? (BS2)

Mike Green

Connecting 6V to an I/O pin is certainly enough to damage the I/O pin and possibly the Stamp itself. The crucial question is whether the current is limited. Most CMOS ICs including the Stamp have protective diodes, one from each I/O pin to Vdd (the +5V supply) and another from each I/O pin to Vss (the supply ground). These diodes conduct when there's a voltage above roughly +5.7 or below roughly -0.7V and shunt the excess current (and voltage) to the power supply pins. This scheme works for currents up to roughly 500uA. Beyond that, the diodes and the conductors (wires) on the chip can be damaged (melted). It sounds like there was nothing to limit the current from the 6V Vin supply to I/O pins 15 and 14. You might be able to just ignore I/O pins 14 and 15 and use the rest of the Stamp. If you need the two I/O pins, you'll have to replace the Stamp. Call Parallax Tech Support.

electrosys

The Basic Stamp at HomeWorker Board, has another feature, with 220 ohm resistors across all I/O pins, these resistors will prevents accident, like wrong connection, currents overload etc.

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