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3 page 
FUNCTIONAL DESCRIPTION PIN DEFINITIONS Copyright Semtech, 1997-2001 DOC5-FJL-DS-106 www.semtech.com 3 The GreenCoderTM consists functionally of seven major sections (see Functional Diagram, previous page). These are the Keyboard Encoder, a 16-Bit Timer, the Mode Control Unit, the Data Buffer, the Interrupt Control, the PC Commun- ication Channel and the 8042 Emulation Channel. All sections communicate with each other and operate concurrently. Mnemonic DIP PLCC QFP Type Name and Function VCC 40 44 38 I Power Supply: +5V VSS 20 22 17 I Ground OSCI 39 43 37 I Oscillator input OSCO 38 42 36 O Oscillator output _RESET 1 1 41 I Reset: apply 0V to provide orderly start-up EKC1 37 41 35 I External Keyboard Clock 1:connects to external keyboard clock line and is used to generate an interrupt for every clock line transmission VX 3 4 43 I Tie to Vcc OPT 6 7 2 I Used for options selection KC 8 9 4 I/O Keyboard Clock: connects to PC keyboard port data line KD 7 8 3 I/O Keyboard Data: connects to PC port data line EKD 10 11 6 I/O External Keyboard Data: connect to external keyboard clock line EXC 9 10 5 I/O External Keyboard Clock 1: connects to external keyboard data line DRV 2 2 42 I Wake-up line: used for sleep mode R0-R5 29-34 32-37 27-32 I Row Data Inputs R6 5 6 1 I R7 36 39 34 I C0-C4 12-16 13-17 8-12 I/O Column Select Outputs: select 1 of 16 C5-C7 17-19 19-21 13-15 O columns C8-C15 28-21 31-24 26-18 O CL 11 12 7 O Caps Lock LED NL 4 5 44 O Num Lock LED SL 35 38 33 O Scroll Lock LED NC 3,18 39-40 No Connects: these pins are unused 23,40 16,22 Note: An underscore before a pin mnemonic denotes an active low signal. KEYBOARD ENCODER The encoder scans a keyboard organized as an 8 row by 16 column matrix for a maximum of 128 keys. Smaller-size keyboards are support- ed provided that all unused row lines are pulled to Vcc. When active, the encoder selects 1 of the 16 column lines (C0-C15) every 512 µS and then reads the row data lines (R0-R7). A key closure is detected as a 0 in the corresponding position of the matrix. A complete scan cycle for the entire keyboard takes approximately 9.2 mS. Each key found pressed is debounced for a period of 20 mS. Once the key is verified, the corresponding key code(s) are loaded into the transmit buffer of the PC keyboard communication channel. Scan Code Table Sets The UR5HCFJL supports all three scan code table sets. Scan Code Table Set 3 allows the user to program individual key attributes such as Make/Break and Typematic or Single-Touch Action. For more information, refer to the IBM Tech- nical Reference Manuals. Custom scan code tables, including macros, are also available. |
