DL7942 Datasheet PDF - QiXin

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DL7942
QiXin

Part Number DL7942
Description single chip keyboard encoder
Page 22 Pages


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DL7942
键盘 IC
GENERAL DESCRIPTION
The DL7942 a single chip keyboard encoder developed for IBM PC AT, IBM PS2 and compatible machine keyboard.
The device detects the key press and release activity, sends the scan code to system, and accepts the command from system.
A high performance, low cost keyboard can be achieved by using the DL7942 with the minimal external components.
FEATURES
Support scan code set 1, 2 and 3.
Support PC AT and PS/2 keyboard.
104/107 keys with with multi media or other special application keyboard encoder.
Support WINDOWS95, 98, 2000 keys.
IBM PC AT or compatible machine keyboard
IBM PS/2 model 30, 50, 60, 80 or compatible machine keyboard.
Phantom key detects.
Built-in RC oscillator with external resistor.
Internal pull-up resistor for inputs.
Tri-state outputs.
Low power CMOS device technology.
APPLICATION
PIN DESCRIPTION
PIN NO
Pin Name
1 GND
2 OSCO
3 DATA
4 CLK
245611~1522232119
19181716202526
C0~C17
27~34
R0~R7
78910
NC
35 SCRL
36 NUM
37 CAPS
38 NC
39 VDD
40 OSCI
Direction
POWER
O
I/O
I/O
Function description
Negative power supply pin
Clock output
Data line of serial port
Clock line of serial port,
O Keyboard matrix scanning output pins
I
-
O
O
O
TEST
POWER
I
Keyboard matrix scanning input pins
No connection
Scroll Lock indicator
Num Lock indicator
CAPS lock indicator
--
Positive power supply pin
External oscillator resistor connection pin
FUNCTION DESCRIPTIONS
The DL7942‘s main function is to detect key press and release activity and to transmit the corresponding scan code, as
well as make and break codes to the system. The device also accepts commands from the system. The communication
between the keyboard and the system is realized via a serial port consists of CLOCK and DATA pins.
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DL7942
键盘 IC
Power-on-reset and self-test
The power-on-reset (POR) occurs first when power is applied to the keyboard. The duration of POR is 150ms~2s.
After POR, the self-test BAT (Basic Assurance Test) happens, it takes 300ms~500ms.
The following activities take place in BAT:
1) Turns on LED indicators at the beginning.
2) Test.
3) Turns off LED indicators at the end
4) Send the result to the system.
A completion code AA is send to the system if BAT is successful. an error code is if BAT fails. BAT takes
300ms-500ms the completion codes are send 450ms-2.5s after POR, and 300ms~500ms after RESET command is
acknowledged.
Keyboard buffer
An FIFO is used to buffer the received scan code.
1) The buffer is 16-byte
2) Respond codes, i.e FA and repeated codes isn‘t be buffered.
Additional keystroke is discarded.
Command description
Command from the system
ResetFF(hex)
Send ACK to system
Checks clock and data limes-Reset in the high state for at least 500ms or receives another command.
Default to scan code set 2.
ResendFE(hex)
Sends the previous code again. If the previous code is RESEND, the last code before RESEND will be send .
Set Key Type-FB, FC, FD (hex)
Keyboard responds with ACK
Clears output buffer
Receivers key ID byte
Receivers ACK
Sets key ID type (affect only scan code set 3 operation).
FB: Typematic
FC: Make/Break
FD: Make
Returns to previous scanning rate.
Set All Keys-F7, F8, F9, FA(hex)
Sends ACK to the system
Clears output buffer.
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DL7942
键盘 IC
Sets all key type to the type specified by the command (affect only scan code set 3 operation).
F7: Typematic
F8: Make /Break
F9: Make
FA: Typematic /Make/Break
Returns to previous scanning rate.
Set Default - F6(hex)
Sends an ACK to system
Resets all conditions to power-on state
Clears the output buffer
Set the default key type(scan code set 3 only).
Set the default typematic rate/delay.
Default Disable-F5(hex)
Sends an ACK to the system.
Resets all condition to power-on state.
Clears the output buffer.
Sets the default key type (scan code set 3 only).
Set the default typematic rate/delay.
Clear last typematic key.
Stops scanning and wait for commands
Enable-F4(hex)
Sends and ACK to the system
Clears the output buffer.
Clears the last typematic key.
Start scanning
Set Typematic Rate/Delay F3(hex)
Sends an ACK to the system.
Receivers rate/delay value byte
Sends and ACK to the system.
Set rate/delay.
Returns to previous scanning state.
Note:
1. Repeat period=(8+A)×(2B)×0.00417s
A. Binary value of bits 2, 1, and 0.
B. Binary value of bits 4 and 3.
2. Delay=(C+1)×250ms
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DL7942
A. Binary value of bits 6 and 5.Bit 7 is always 0
B4b0
Typematic rate
00000
00001
00010
00011
00100
00101
00110
00111
01000
01001
01010
01011
01100
01101
01110
01111
3.Default rate=10.9 chars/sec+20%
Default delay =500ms±20%
30.0
26.7
24.0
21.8
20.0
18.5
17.1
16.0
15.0
13.3
12.0
10.9
10.0
9.2
8.6
8.0
B4b0
10000
10001
10010
10011
10100
10101
10110
10111
11000
11001
11010
11011
11100
11101
11110
11111
Read ID-f2 (hex)
Sends an ACK to the system
Discontinues scanning.
Sends two ID bytes. The second byte will be sent within 500 us after first byte.
Resumes scanning.
Select Alternate Scan Codes-F0(hex)
Sends an ACK to the system.
Clears the output buffer.
Sets the default typematic rate/delay.
Clears last typematic key.
Receives option byte.
Sends an ACK to the system.
Option byte=
01: scan code set 1
02: scan code set 2
03: scan code set 3
Returns to previous scanning rate.
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键盘 IC
Typematic rate
7.5
6.7
6.0
5.5
5.0
4.6
4.3
4.0
3.7
3.3
3.0
2.7
2.5
2.3
2.1
2.0



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