Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 KBDSER132 IC Serial output keyboard encoder for up to 132 keys General Description The KBDSER132 IC is designed to provide a serial binary output encoder for keyboards up to 132 keys. The KBDSER132 IC contains all the logic necessary to encode a SPST keyboard switch array up to 12 by 11 in size and provide a serial binary output. The output is standard asynchronous format, using 8 bits, 1 stop and no parity at 9600 BPS. Other formats and encoding are available, contact the factory. The array can be a 12 x 11 array, but any smaller size may be used. The KBDSER132 handles debouncing and encodes the keys with no external parts. All timing is internally generated. No external diodes are required in the array to prevent key ghosting in a two key rollover situation. A .1 uF bypass capacitor is suggested across the VDD and VSS pins. The part uses the standard 28 pin .3 inch width SOIC package. Features • Asynchronous serial output • Fully encodes a key switch array. • • • • • • • • • • • • (up to 12 x 11) No external parts required. Low power consumption 5 mA typical. Supply voltage 2.4 to 5.25 volts. All timing internally generated. 2 Key rollover. On chip row input resistors. Applications • Data Entry • Security Alarms • Handheld devices • Machine Control • Numeric Entry • Telephones • Computers • Controls • Gaming Internal key bounce elimination. TTL and CMOS compatible outputs. Part is in full production. SOIC and DIP 28 Pin Package. ROHS Compliant Low EMI Part Number 74C922-SO Copyright © 2014 ABCircuits. Revised September 2014 Page 1 of 9 Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 Example Circuits 132 KEY RS-232 ENCODED KEYBOARD VCC 28 27 26 25 24 23 22 21 20 19 18 17 16 15 VCC 16 VDD COLX10 COLX8 ROWY11 ROWY9 ROWY7 ROWY5 ROWY3 ROWY1 NC COLX7 COLX5 COLX3 COLX1 C5 .1 1 C1+ 3 C6 .1 C2+ V+ +5 C7 .1 2 V- 6 C8 .1 C2- 11 T1in 10 T1out T2in 12 T2out R1out KEYPAD 9 R2out R1in R2in RS232 DB9S J1 1 2 3 4 5 6 7 8 9 8 14 7 13 8 TXD GND 15 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 U2 SEE NOTES C1- 4 5 C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 VCC COLX11 COLX9 ROWY12 ROWY10 ROWY8 ROWY6 ROWY4 ROWY2 NC SOUT COLX6 COLX4 COLX2 VSS GND KBDSER132 1 2 3 4 5 6 7 8 9 10 11 12 13 14 11 X 12 KEYBOARD MATRIX U2= MAX232 FOR 5V RS232 U2= MAX3232 FOR 3V RS232 132 KEY RS-485 KEYBOARD KBDSER132 1 2 3 4 5 6 7 8 9 10 11 12 13 14 COLX11 COLX9 ROWY12 ROWY10 ROWY8 ROWY6 ROWY4 ROWY2 NC SOUT COLX6 COLX4 COLX2 VSS VDD COLX10 COLX8 ROWY11 ROWY9 ROWY7 ROWY5 ROWY3 ROWY1 NC COLX7 COLX5 COLX3 COLX1 VCC 28 27 26 25 24 23 22 21 20 19 18 17 16 15 VCC U2 1 VCC 2 3 4 RO VCC -RE -DO/-RI DE DO / RI DI GND 8 7 6 RS485 OUT 5 U2 75176 FOR 5V U2 MAX3485 FOR 3.3V R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 KEYPAD C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 11 X 12 KEYBOARD MATRIX Part Number KBDSER132 Copyright © 2014 ABCircuits. Revised September 2014 Page 2 of 9 Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 132 KEY ETHERNET KEYBOARD COLX11 COLX9 ROWY12 ROWY10 ROWY8 ROWY6 ROWY4 ROWY2 NC SOUT COLX6 COLX4 COLX2 VSS VDD COLX10 COLX8 ROWY11 ROWY9 ROWY7 ROWY5 ROWY3 ROWY1 NC COLX7 COLX5 COLX3 COLX1 +3.3 28 27 26 25 24 23 22 21 20 19 18 17 16 15 +3.3 LANTRONIX XPORT 1 2 3 4 5 6 7 8 GND +3.3 -POR OUT IN CP1 CP2 CP3 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 KEYPAD C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 11 X 12 KEYBOARD MATRIX Part Number KBDSER132 Copyright © 2014 ABCircuits. Revised September 2014 Page 3 of 9 ETHERNET KBDSER132 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 Connection Diagram KBDSER132 1 2 3 4 5 6 7 8 9 10 11 12 13 14 COLX11 COLX9 ROWY12 ROWY10 ROWY8 ROWY6 ROWY4 ROWY2 NC SOUT COLX6 COLX4 COLX2 VSS VDD COLX10 COLX8 ROWY11 ROWY9 ROWY7 ROWY5 ROWY3 ROWY1 NC COLX7 COLX5 COLX3 COLX1 28 27 26 25 24 23 22 21 20 19 18 17 16 15 Pin Description Pin # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Description Col X11 Col X9 Row Y12 Row Y10 Row Y8 Row Y6 Row Y4 Row Y2 NC SOUT Col X6 Col X4 Col X2 VSS Pin # 28 27 26 25 24 23 22 21 20 19 18 17 16 15 Description VDD Col X10 Col X8 Row Y11 Row Y9 Row Y7 Row Y5 Row Y3 Row Y1 NC Col X7 Col X5 Col X3 Col X1 Col X1 – Col X11 These pins are open drain column driver outputs to the key matrix. Row Y1 – Row Y12 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 rates 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. Part Number KBDSER132 Copyright © 2014 ABCircuits. Revised September 2014 Page 4 of 9 Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 NOTES: Make no connection to the NC pins. Pins 9 and 19 must be left unconnected. Truth Table The output codes of the KBDSER132 start at zero, and progress upwards in a binary count. Custom output codes are available, consult the factory for information. COLX1 COLX1 COLX1 COLX1 COLX1 COLX1 COLX1 COLX1 COLX1 COLX1 COLX1 COLX1 COLX2 COLX2 COLX2 COLX2 COLX2 COLX2 COLX2 COLX2 COLX2 COLX2 COLX2 COLX2 COLX3 COLX3 COLX3 COLX3 COLX3 COLX3 COLX3 COLX3 COLX3 COLX3 COLX3 COLX3 COLX4 COLX4 COLX4 COLX4 COLX4 1 X 2 3 4 5 ROWY 6 7 8 9 10 11 12 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X HEX 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F 20 21 22 23 24 25 26 27 28 Part Number KBDSER132 Copyright © 2014 ABCircuits. Revised September 2014 Page 5 of 9 Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 COLX4 COLX4 COLX4 COLX4 COLX4 COLX4 COLX4 COLX5 COLX5 COLX5 COLX5 COLX5 COLX5 COLX5 COLX5 COLX5 COLX5 COLX5 COLX5 COLX6 COLX6 COLX6 COLX6 COLX6 COLX6 COLX6 COLX6 COLX6 COLX6 COLX6 COLX6 COLX7 COLX7 COLX7 COLX7 COLX7 COLX7 COLX7 COLX7 COLX7 COLX7 COLX7 COLX7 COLX8 COLX8 COLX8 COLX8 COLX8 COLX8 COLX8 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X 29 2A 2B 2C 2D 2E 2F 30 31 32 33 34 35 36 37 38 39 3A 3B 3C 3D 3E 3F 40 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F 50 51 52 53 54 55 56 57 58 59 5A Part Number KBDSER132 Copyright © 2014 ABCircuits. Revised September 2014 Page 6 of 9 Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 COLX8 COLX8 COLX8 COLX8 COLX8 COLX9 COLX9 COLX9 COLX9 COLX9 COLX9 COLX9 COLX9 COLX9 COLX9 COLX9 COLX9 COLX10 COLX10 COLX10 COLX10 COLX10 COLX10 COLX10 COLX10 COLX10 COLX10 COLX10 COLX10 COLX11 COLX11 COLX11 COLX11 COLX11 COLX11 COLX11 COLX11 COLX11 COLX11 COLX11 COLX11 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X 5B 5C 5D 5E 5F 60 61 62 63 64 65 66 67 68 69 6A 6B 6C 6D 6E 6F 70 71 72 73 74 75 76 77 78 79 7A 7B 7C 7D 7E 7F 80 81 82 83 Part Number KBDSER132 Copyright © 2014 ABCircuits. Revised September 2014 Page 7 of 9 Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 Absolute Maximum Ratings Symbol Description Tstg Ta V dd V io Imio ESD Storage Temperature Operating Temperature LU Latch up current V dd - V ss Voltage Input Voltage Maximum current into any pin Electrostatic Discharge Voltage Min -55 -40 -0.5 Typical Max Units 25 +100 +85 +6.0 ºC ºC V V mA V Vss - 0.5 -25 2000 V dd +0.5 +50 200 Notes Human Body Model ESD mA DC Electrical Characteristics Symbol Description V dd Idd V oh V ol V ih V il Ioh Iol Cio Iil Rpu Supply Voltage Supply Current High Output Level Low Output Voltage Input High Level Input Low Level High Level Source Current Low Level Sink Current Capacitive load Input leakage Pull Up Resistors On Row Inputs Min Typical Max Units 5 5.25 8 V mA V V V V mA mA pF nA k? 2.4 V dd - 1.0 0.75 2.1 4 3.5 1 5.6 0.8 10 25 10 8 Notes Note 1 Ioh=10 mA Iol=25 mA Note 1: Vdd=5VDC, all inputs and outputs open Theory Of Operation The KBDSER132 IC is a custom programmed microprocessor designed to encode keyboards and provide a serial output. The open drain COL X pins are pulsed low one at a time, and the ROW Y 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 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. A program such as REALTERM may be used to view the binary data as hexadecimal. Hyperterm will not show data in hexadecimal format. Part Number KBDSER132 Copyright © 2014 ABCircuits. Revised September 2014 Page 8 of 9 Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 Physical Dimensions SOIC-28 Physical Dimensions 28 Pin Dip Package (-DIP Suffix) Close but not quite? Our products are software based, we can modify existing parts to fit your needs at a minimal cost or create new parts designed to your specifications. Email us and we can make a chip for you! For the latest version of this spec sheet, visit www.abcircuits.com 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. Part Number KBDSER132 Copyright © 2014 ABCircuits. Revised September 2014 Page 9 of 9