Decimal to BCD Convertor: This circuit will provide an output in Binary Coded Decimal from any of the input switches. The input switches may be expanded to 16 switches, providing a Hexadecimal to BCD conversion.

Key Reading Circuit Saves I/O Pins: 03/06/03 EDN-Design Ideas / PDF contains multiple circuits - scroll to find this circuit

Keypad Encoder Commands Tape Transport: 09/02/96 EDN-Design Ideas

Keypad sequence activates relay: 10/12/00 EDN-Design Ideas / PDF contains multiple circuits - scroll to find this circuit

Low Power Keypad Consumes only 100 NA : 01/24/02 EDN-Design Ideas / Often in the use of products with keypads, one or more keys become "stuck" or are being pressed.

Low power keypad consumes only 100 nA: 01/24/2002 EDN - Design Ideas / Often in the use of products with keypads, one or more keys become "stuck" or are being pressed. For example, a cell phone in the bottom of a purse or in a hip pocket could have one or more of its keys inadvertently pressed and held down for a considerable period. Depending on the circuit design and implementation of the keypad interface, this condition could cause excess current to flow,... .

Novel idea implements low cost keyboard: 04/03/03 EDN-Design Ideas / Many applications that use a microcontroller also use a keyboard. If your application uses a relatively powerful microcontroller, you can use several free I/O pins or an unused input with an ADC to effect an easy keyboard connection. But, if the microcontroller in your system has too few free I/O pins and no on-chip ADC, you can be in trouble...

One Pin Keypad Features Low Component Count: 05/26/03 Electronic Design - Ideas for Design / While current-shunt-monitor ICs like the INA168 can be connected to current-shunt resistors at supply voltages of up to 60 V, the circuit shown in the figure allows current sensing at even higher voltages....

OnePin Keypad Interface Conserves Battery Power : 11/11/02 Electronic Design - Ideas for Design / This idea builds on a previous IFD, "Connect Any Keypad With Any Microcontroller Using Only One Pin" (electronic design, May 1, 1998, p. 126), where a 555 timer connects a keypad switch matrix to a microprocessor. The timer converts a...

PIC Based Keyboard Emulator:

RS232C Serial Port Scans Remote Keypad: 12/04/97 EDN-Design Ideas

Security Circuit Eschews Sophistication: 05/26/94 EDN-Design Ideas

X Y Keypad uses ?C`s Serial Port: 10/10/96 EDN-Design Ideas