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PDF DL7942 Fiche technique - QiXin

Numéro de référence DL7942
Description single chip keyboard encoder
Fabricant QiXin 
Logo QiXin Logo 

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DL7942 Datasheet, Description
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 Fiche technique
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
3 页 共 22

3 Page

DL7942 pdf
DL7942
键盘 IC
Data Communication via Serial Port
Data output
The keyboard first checks the CLK and DATA lines. If both of them are high, that means data transmission from
keyboard to the system is permitted, then keyboard starts to clock data out. Data will be valid before the trailing edge and
after the leading edge. The keyboard checks the clock line at least every 60us. If the clock line is lowered before the
leading edge of the 10th clock, the keyboard should stop sending, and set both data line and clock line to high.
.Data input
The system checks the CLK line first. If the keyboard is not sending data or it is sending data but has not reached the
10th clock, the system can force the clock line low for more than 60us and prepares to send data.
The keyboard checks clock line status at intervals of no more than 5ms. If a system-request-to-send (RTS) is
detected, the keyboard clocks 11 bit in. After the 10th bit, the keyboard checks the data line. If the data line is high, the
keyboard pulls it low and clocks one more bit to signal the system that data has been received.
If data is low after the 10th bit, a frame error occurs. When a frame error occurs, the keyboard should continue to
count until data line goes high , then pulls it low and sends a RESEND command to the system.
Keyboard Scan Code Table
The keyboard supports 3 scan code sets. When a key is pressed down, its make scan code is sent to the system.
When the key is released, its break code is sent. If two or more keys are held down, only the last key pressed repeats at
the typematic rate. Typematic operation stops when the last pressed key is released
Scan code set 1
Key
`()
1
2
3
4
5
6
7
8
9
0
-(-)
=(+)
BACKSPACE
TAB
Q
W
Make code
29
02
03
04
05
06
07
08
09
0A
0B
0C
0D
0E
0F
10
11
Break code
A9
82
83
84
85
86
87
88
89
8A
8B
8C
8D
8E
8F
90
91
Key
X
C
V
B
N
M
,(<)
.(>)
/(?)
SHIFT_R
CTRL_L
ALT_L
SPACE
ALT_R
CTRL_R
NUM
(7)
6 页 共 22
Make code
2D
2E
2F
30
31
32
33
34
35
36
ID
38
39
E038
E01D
45
47
Break code
AD
AE
AF
B0
B1
B2
B3
B4
B5
B6
9D
B8
B9
E0B8
E09D
C5
C7

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