3 ms·
Here's a dramatically simplified diagram to illustrate the principle: https://db.tt/Fvs0xBpd https://db.tt/Fvs0xBpd If I put a voltage on pin 2, and key A is
by dools 13y ago
Here's a dramatically simplified diagram to illustrate the principle:
https://db.tt/Fvs0xBpd https://db.tt/Fvs0xBpd
If I put a voltage on pin 2, and key A is pressed, I will get a voltage at pin 1. If I put a voltage on pin 3 and key B is pressed, I will get a voltage at pin 1.
It doesn't matter if both are pressed simultaneously because I am reading them sequentially.
All you have to do is scan the keys quickly enough that someone can't "sneak in" a key press in between scans which turns out is possible with even the lowest powered hardware.
- jfoks 13y agoGhosting is with three keys pressed: If there is a key A that is in the same row as a key B plus and also in the same column as a key C, then a fourth key (the 'ghost') appears to be pressed in the column of key B and the row of key C due to the shorting of the rows and columns, also in your scheme.
- dools 13y agoThere are no columns in this design. The behaviour you're describing can't occur since this isn't a 2d matrix of keys. The keys are grouped such that putting voltage on an input pin will result in an output voltage on many pins depending on which keys are pressed at the time.