??? 08/02/06 05:05 Read: times |
#121539 - No! Responding to: ???'s previous message |
Erik said:
The keypad (if reasonably close to the processor) will work equally well with weak pull-up as with push-pull. Hardly! If you use push-pulls in the rows, you can short-circuit port outputs, when two or more switches are pressed at the same time. Even if no damage will occur, then this will at least result in huge supply and ground currents, causing ground bounce within the micro and, in worst case, eroding the low level noise margin. Such a design cannot be recommended at all! Kai |