EDE1144SO 查看數據表（PDF） - Unspecified
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EDE1144SO Datasheet PDF : 7 Pages
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4x4 Multiplexed Keypad
0
1
2
3
4
5
6
7
8
9
10 11
12 13 14 15
Row 0
Row 1
Row 2
Row 3
Column 3
Column 2
Column 1
Column 0
EDE1144
Keypad
Encoder
EDE1144 Keypad Encoder IC
Data Output
D0
D1
D2
D3
Serial
Output
Data
Valid
Beeper
Output
2400 / 9600 Baud Select Input
Figure One: Connection Block Diagram
As illustrated by Figure One, the EDE1144 resides between the keypad and host microcontroller/
processor. The host microcontroller receives keypress data via either the four parallel data
outputs (D0-D3, Pins 6-9) or the Serial Data Output (Pin 1). The Data Valid signal (Pin 17) is
activated upon keypress (and upon each key repeat cycle if key is held). The Data Valid signal is
activated prior to transmission of the serial data to allow polled (software-UART) style host serial
systems such as the BASIC Stamp™ or a microcontroller without a hardware UART to enter the
serial receive routine and receive the keypress data without needing to continually wait for the
start bit. Note that the data outputs to the host microcontroller reside on the row output pins
(Pins 6-9), therefore parallel-output data should only be read while the Data Valid (Pin 17) signal
is active (low). Upon powerup, the four data output pins will be high, and will remain high
except when a key is pressed.
The following table illustrates the data values returned by the serial and parallel outputs of the
EDE144 upon each keypress. Note that the serial values are increased (by Hexadecimal 30 ($30)
for 0-9 and Hex $37 for 10-15) to correspond to the ASCII equivalent (0-9,A-F) of the BCD
(binary-coded decimal) value on the parallel outputs.
Key:
RS-232:
D3..D0:
0
$30
('0')
0000
1
$31
('1')
0001
2
$32
('2')
0010
3
$33
('3')
0011
4
$34
('4')
0100
5
$35
('5')
0101
6
$36
('6')
0110
7
$37
('7')
0111
Key:
RS-232:
D3..D0:
8
$38
('8')
1000
9
$39
('9')
1001
10
$41
('A')
1010
11
$42
('B')
1011
12
$43
('C')
1100
13
$44
('D')
1101
14
$45
('E')
1110
15
$46
('F')
1111
Table One: Keynumber vs. Output Data
Page 3/7
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