Electronic Circuits and Tutorials
Electronics Schematics - K

Keypad Circuits

4 Bit µP's A/D Converter Decodes Keypad's Inputs - 10/13/94 EDN-Design Ideas: Fig 1 shows a Mitsubishi M50927-XXXSP/FP 4-bit microcontroller decoding a 4×4 keypad using only four digital I/O lines instead of eight. Saving four of a 4-bit µC's precious I/O lines could be significant.

4 Digit Keypad - (electronic design)

A 4-Digit Keypad Controlled Switch circuit db - This is a universal version of the Four-Digit Alarm Keypad . I have modified the design to free up the relay contacts. This allows the circuit to operate as a general-purpose switch. It also means....

A Decimal to BCD Decoder - This circuit will take the input from a keypad with up to 16 buttons, and convert it into a ''latched'' BCD output.

Alarm control keypad - (circuit / schematic design)

AN528: Implementing Wake-Up on Keystroke - Microchip Application Note Published 26-Aug-97  (app note)

AN529: Multiplexing LED Drive & 4x4 Keypad Sampling - Microchip Application Note Published 26-Aug-97  (app note)

AN552: Implementing Wake Up on Keystroke - Microchip Application Note Published 26-Aug-97  (app note)

AN557: Four Channel Digital Voltmeter with Display & Keyboard - Microchip Application Note Published 27-May-05  (app note)

AN-734: MF2 Compatible Keyboard with COP8 Microcontrollers - National Semiconductor Application Note  (app note)

AT89C2051/4051scanning 7 Segment Display & Keypad - (circuit / schematic design)

AVR 2x16 LCD & 4x4 keypad driver - A very simple circuit to experiment with AT90S2313, 2x16 LCD display and 4x4 keypad. The clock based on 4 MHz crystal, but you can use anyone crystal between 1-4 MHz. The keys with the name "A", "B" ... "F" are typed to the LCD with numbers 10-16. Because the AVR have only 15 I/O pins we are working the LCD display with 4-bit data bus. The 4 resistors (10K) are to protect the AVR from the shortcuts as the column of the keypad is change.

Camera Serializer/Deserializer Chip Set Reduces Wire Count for Keypad - 04/28/05 EDN-Design Ideas: Keypad interconnect needs just four wires.....(design idea)

Connect a 2x16 characters LCD display to a 4x4 keypad - Connect some 2x16 characters LCD display and 4x4 keypad with AVR microcontroller  (electronic design)

µC Implements Pushbutton Light Dimmers - 06/18/98 EDN-Design Ideas:  A project required building a synchronous-demodulator circuit to track a line drawn on paper.  beauty of  synchronous-modulator/demodulator approach is its inherent noise rejection.  method rejects nearly….....(design idea)

µC Provides Wireless Keypad Control - 10/08/98 EDN-Design Ideas: Scroll to find specific article.  Portable systems, such as telephone handsets, make extensive use of low-dropout (LDO) regulators. se components provide noise-sensitive parts with a stable power-supply line.....(design idea)

2 Way IR Term - This unit provide 2 way IR communications using a numeric keypad and an LCD display.  Data is sent and received in ASCII with no regard to what the data means to any particular device.

2 wire 4 by 4 key keyboard interface saves power - 08/17/06 EDN-Design Ideas: Resistor matrix and microcontroller encode keypad.....(design idea)

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