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Keypad Circuits   Page 4
Key Pads:  #'s - C      D - I      K - L      M - Z
Last Updated on: Wednesday, November 29, 2017 05:40 AM
 


Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

MF2 Compatible Keyboard with COP8 MicroControllers -  National Semiconductor Application Note  (app note added 2/06)
MIDI Keyboard -  (electronic circuit added 4/05)
Multiplexing LED Drive & 4x4 Keypad Sampling -  Microchip Application Note Published 26-Aug-97  (app note added 2/06)
Novel idea implements low-cost keyboard -  3-Apr-03 Issue of EDN  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..... [Design Idea by Jean-Jacques Thevenin, Thomson Plasma, Moirans, France]
PIC LCD & Keypad Driver -  (circuit / schematic design added 6/06)
PS/2 Keyboard Keystroke Logger Based on Atmel 89C2051 -  (electronic circuit added 4/05)
RS232C Serial Port Scans Remote Keypad -  12/04/97 EDN-Design Ideas.....In many embedded or control applications, you might prefer to use a small,...[Design Idea by SK Shenoy, NPOL, Kochi, India]
Scheme improves on low-cost keyboard -  30-Oct-03 Issue of EDN  You can easily improve on a previous Design Idea to produce a slightly simpler resistor arrangement with better timing balance between switches, using a single resistor value (Reference 1, Figure 1]. The use of a single resistor value, RS, in a series chain for the switch resistors gives the timing parameters a simpler format and should reduce bill-of-materials cost..... [Design Idea by Martin O'Hara, Telematica Systems Ltd, Cranfield, Bedfordshire, UK]
Security Circuit Eschews Sophistication -  05/26/94 EDN-Design Ideas.....Because of the many states involved in implementing sequential combination locks, most designers use a microcontroller or a PLD. But for those die-hard discrete designers who don't want to bother with debugging programs, here's a dead-simple circuit that verifies a security code's entry from a 10-digit keypad..... EDN is migrating links. This link is not verified.  Search the "title" + "EDN" for new link.

Security Keypad -  This Electronic Code Lock uses a 12-keys keypad is used to enter a password and open an electrick lock or any other device with a signal. Uses an 8-pin PIC 12F629. (11/04)
Security Keypad II -  An improved version that can be used on security vaults, Doors with electric latches, Alarms, Safety devices and many other uses. It uses an HITACHI LCD (16x1 or 8x1) and a matrix keypad. The HEX code is available for 16F84A and 16F628. (added circuit 5/06)
Ser-Key 10-Key Serial Keypad Encoder -  (electronic circuit added 4/05)
Single-wire keypad interface frees microcontroller-I/O pins -  31-Mar-05 Issue of EDN  Using this interface topology, you can reduce the number of keypad interface wires to just one and thus save critical microcontroller I/O ports..... [Design Idea by Israel Schleicher, Prescott Valley, AZ; Edited by Brad Thompson]
Sun Type 5 keyboard on the PC -  Many people have dreamed of having their Sun Type 5 keyboard attached to their PC. Now with this adapter, it is finally possible. Because the standard Sun keyboards use TTL RS232 at 1200 bps to talk to the Suns, it's relatively easy to make them talk to any non-Sun computer by converting this to true RS232. However PC's don't understand keyboards hooked up to serial ports without special drivers. While such drivers do exist you will still need to keep a PC keyboard about if you want to change the BIOS setup etc..... [Jonathan A. Buzzard]
TB056: Demonstrating the *set_report* Request: With PS/2® to USB Keyboard Translator Example -  Microchip Application Note Published 4-May-04  (app note added 2/06)
Touch Keypad -  This board layout was created using the SOIC version of a PIC16F627A without drawing the usual schematic first.  Most of the part values are etched on the Layout.   The SIP resistor packs I used are 10k ohm, some experimentation with this value may be useful.....(circuit added 08/08/08) [Luhan Monat - Mesa Arizona]
Two-wire, four-by-four-key keyboard interface saves  -  08/17/06 EDN-Design Ideas.....You can use a microcontroller that includes an ADC to design a two-wire-plusground keyboard interface. For example, you can use a resistive voltage divider to identify a pressed key (Reference 1). A microcontroller’s integrated ADC typicallyou can use a microcontroller that includes an ADC to design a two-wire-plusground keyboard interface. For example, you can use a resistive voltage divider to identify a pressed key (Reference 1). A microcontroller’s integrated ADC typically..... [Design Idea by Stefano Salvatori, University of Rome, Rome, Italy; and Gabriele Di Nucci, EngSistemi, Rome, Italy]
White LED driver backlights LCD and keypad -  13-Nov-03 Issue of EDN  Designers widely use white LEDs to backlight color LCDs and keypads in handheld devices, such as cell phones, MP3 players, GPS navigators, and PDAs. Their spectrum and brightness represent near-ideal light sources. One possible configuration for a phone or a phone/PDA combination is to have a group of three LEDs to light the display and six LEDs for the keypad..... [Design Idea by Fabien Franc, Catalyst Semiconductor, Sunnyvale, CA]
White LED driver provides 64 step logarithmic dimming -  10-Jun-04 Issue of EDN  The circuit of Figure 1 is designed for portable-power applications that require white LEDs with adjustable, logarithmic dimming levels. The circuit drives as many as four white LEDs from a 3.3V source and adjusts the total LED current from 1 to 106 mA in 64 steps of 1 dB each. The driver is a charge pump that mirrors the current ISET (sourced from IC3's SET terminal] to produce a current o..... [Design Idea by William Hadden, Maxim Integrated Products, Sunnyvale, CA]
Wired USB Keyboard -  (application / block diagram added 6/07)
XY Keypad uses µC's Serial Port -  10/10/96 EDN-Design Ideas.....Interfacing an X-Y keypad to a microcontroller usually uses a parallel port of 8 bits or more. But with the circuit shown in Figure 1, a more efficient interface using a microcontroller's serial port reduces the number of connections required from eight to three.  This interface uses the MM74C922N, a National Semiconductor keypad encoder,..... [Design Idea by James Mears, National Semiconductor, Tacoma, WA]
Key Pads:  #'s - C      D - I      K - L      M - Z


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