KBDGRAY ABCIRCUITS | Alldatasheet

Document overview

  • Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
  • PDF pages: 6

Technical content

Features

  • Asynchronous serial output. ASCII 0-9, #, *, and A -D (on 16 key keypads)
  • Fully encodes a key switch array . (up to 4 x 4)
  • No external parts required .
  • Low power consumption 2 mA typical.
  • Supply voltage 2.4 to 5 .25 volts.
  • All timing internally generated .
  • 2 Key rollover.
  • On chip row input resistors .
  • Internal key bounce elimination .
  • TTL and CMOS compatible outputs .
  • Part is in full production .
  • SOIC 20 Pin Package .
  • Low EMI
  • ROHS Compliant

Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 Part Number KBDGRAY December 2012 Page 2 of 6 Example Circuits VCC DB9S VCC KBDGRAY COLX2 NC COLX1 SOUT NC NC ROWY1 ROWY2 ROWY3 ROWY4 NC NC COLX3 VSS NC COLX4 NC NC VDD NC SEE NOTES 1615 11 14 10 7 12 13 9 8 C1+ C1- C2+ C2- VCCGND T1in T1out T2in T2out R1out R1in R2out R2in U2= MAX232 FOR 5V RS232 GNDPINS1X8 1 2 3 4 5 6 7 8 9 * 0 # A B C D KEYPAD RS232 U2= MAX3232 FOR 3V RS232

16 KEY RS-232 ENCODED KEYBOARD

  • 0 # KEYPAD KBDGRAY COLX2 NC COLX1 SOUT NC NC ROWY1 ROWY2 ROWY3 ROWY4 NC NC COLX3 VSS NC COLX4 NC NC VDD NC

12 KEY RS-485 ENCODED KEYBOARD

-DO/-RI DO / RI RO DI -RE DE PINS1X7 U2 75176 FOR 5V RS485 OUT U2 MAX3485 FOR 3.3V VCC

Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 Part Number KBDGRAY December 2012 Page 3 of 6 1 2 3 4 5 6 7 8 9 * 0 # A B C D KEYPAD +3.3

16 KEY ETHERNET KEYBOARD

+3.3 ETHERNET LANTRONIX XPORT GND +3.3 -POR OUT IN CP1 CP2 CP3 PINS1X8 KBDGRAY COLX2 NC COLX1 SOUT NC NC ROWY1 ROWY2 ROWY3 ROWY4 NC NC COLX3 VSS NC COLX4 NC NC VDD NC Connection Diagram KBDGRAY COLX2 NC COLX1 SOUT NC NC ROWY1 ROWY2 ROWY3 ROWY4 NC NC COLX3 VSS NC COLX4 NC NC VDD NC Pin Description Pin # Description Pin # Description

1 Row Y1 20 VDD

2 Row Y2 19 NC

3 Row Y3 18 NC

4 Row Y4 17 NC

5 NC 16 NC

6 NC 15 NC

7 NC 14 NC

8 Col X4 13 SOUT

9 Col X3 12 Col X1

10 VSS 21 Col X2

Col X1 – Col X4 These pins are open drain column driver outputs to the key matrix . Row Y1 – Row Y4

Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 Part Number KBDGRAY December 2012 Page 4 of 6 These pins are the row inputs from the key matrix . These inputs have 5.6K (nominal) pull up resistors on chip. SOUT This is the serial output pin. It may be tied directly to the UART receiver input of your UART or microprocessor; to a RS -232 driver such as the MAX232 ; a standard RS485 driver such as the 75176 or an Ethernet interface such as the Lantronix Xport. This pin is high in the idle state, the output format is 8 bits, 1 stop, no parity at 9600 BPS. Other output formats and baud rate s are available, please contact the factory for information. VSS Connect to system ground. VDD Connect to supply voltage of 2.4 to 5 volts . A .1 uF decoupling capacitor to ground is recommended. NOTES: No connection is required to the NC pins . Pins 5 and 15 must be left unconnected . Truth Table Note: To achieve the correct output to match the keys on the Grayhill keyboard , wiring to keyboard must be as shown on the example circuits. On the Grayhill 12 key keyboards, ColX4 is not used. COLX1 COLX2 COLX3 COLX4 ASCII OUT HEX ROWY1 X * 2A ROWY1 X 0 30 ROWY1 X # 23 ROWY1 X D 44 ROWY2 X 7 37 ROWY2 X 8 38 ROWY2 X 9 39 ROWY2 X C 43 ROWY3 X 4 34 ROWY3 X 5 35 ROWY3 X 6 36 ROWY3 X B 42 ROWY4 X 1 31 ROWY4 X 2 32 ROWY4 X 3 33 ROWY4 X A 41 Absolute Maximum Ratings Symbol Description Min Typical Max Units Notes Tstg Storage Temperature -55 25 +100 ºC Ta Operating Temperature -40 +85 ºC Vdd Vdd - Vss Voltage -0.5 +6.0 V Vio Input Voltage Vss - 0.5 Vdd +0.5 V Imio Maximum current into any pin -25 +50 mA ESD Electrostatic Discharge Voltage 2000 V Human Body Model ESD LU Latch up current 200 mA

Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 Part Number KBDGRAY December 2012 Page 5 of 6 Symbol Description Min Typical Max Units Notes Vdd Supply Voltage 2.4 5.25 V Idd Supply Current 2 8 mA Vdd = 5V Voh High Output Level Vdd - 1.0 V Ioh=10 mA Vol Low Output Voltage 0.75 V Iol=25 mA Vih Input High Level 2.1 V Vil Input Low Level 0.8 V Ioh High Level Source Current 10 mA Iol Low Level Sink Current 25 mA Cio Capacitive load 3.5 10 pF Iil Input leakage 1 nA Rpu Pull Up Resistors On Row Inputs 4 5.6 8 k? Theory Of Operation The KBDGRAY IC is a custom programmed microprocessor designed to encode keyboards and provide a serial output. The open drain COLX pins are pulsed low one at a time, and the ROWY pins are sampled to check for key switch closures. If a key is detected, scanning stops until the key is released. The pressed key is encoded to ASCII and transmitted in standard asynchronous format on the SOUT key. The key is transmitted using 8 data bits, 1 stop bit and no parity. Baud rate is 9600 BPS. When the key is released scanning continues.

Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 Part Number KBDGRAY December 2012 Page 6 of 6 Physical Dimensions Design Services Available We can quickly turn your idea into a chip, a pc board, or a finished product. Contact us with your needs and specifications.