MC14497 查看數據表（PDF） - Motorola => Freescale
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MC14497 Datasheet PDF : 8 Pages
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PIN DESCRIPTIONS
E1 – E8
Row Inputs (Pins 1, 2, 10, 11, 14, 15, 16, 17)
Under idle conditions, these inputs are held high by inter-
nal pull–up resistors. As soon as a key is pressed, a logical 0
on that particular line signals to the circuit that a key has
been selected. After a delay of 20 ms, the internal register is
loaded with the code word for the key selected.
E9
Row Input (Pin 3)
This is a special programming input and when connected
to the appropriate scanner output via a diode, it will modify
the transmitted output according to Table NO TAG.
In Table NO TAG, the figures in brackets (FK1, etc.) refer
to the switches shown in the Block Diagram and Figure 3. If
only one option is required, the diode may be omitted. The
connections shown in Table NO TAG may be made in any
combination.
Although E9 is a row input, forcing this line low will not acti-
vate the circuit.
A1 – A4
Scanner Outputs (Pins 4 – 7)
Under idle conditions, these outputs are held low, logical 0.
When a key is pressed, the circuit is activated and the oscil-
lator will start and release the outputs (see Figure 5).
OSCin, OSCout
Oscillator Input and Oscillator Output (Pins 12, 13)
These pins are designed to operate with a 500 kHz ceram-
ic resonator or a tune LC circuit. It is important that a ceramic
resonator and not a filter be used here, as the oscillator fre-
quency cannot be guaranteed if a ceramic filter is used.
SIGNAL OUT
Signal Output (Pin 8)
This output provides the modulating signal ready to drive
the modulation amplifier. If required, the transmitter can be
used as a keyboard encoder for direct use with a receiver. In
this case, the AM option is selected, the output inverted, and
fed directly to the receiver’s signal input pin.
INSTRUCTION
START BIT
A
B
VSS
E1 17 9
VDD
18
E1a
E2
2
E2a
E3
1
E3a
E4
16
E4a
E5
15
E5a
E6
14
E6a
E7
10
E7a
E8
11
E8a
A1 7
A2 6
A3 5
A4 4
FK2
FK1
3 12 13
E9
NOTE: Maximum key contact
resistance = 1 kΩ .
C1 C2
Figure 3. 64–Key Keyboard
C
D
E
F
FSK
f3
f2
f3 f2
f3
f2
f3
f2
f3
AM f1
f1
f1
f1
f1
f1
KEY WORD
DEBOUNCE
20 ms
ONE WORD
9 ms
99 ms
Figure 4. Transmitted Waveforms and Timing (Not Drawn to Scale)
MC14497
4
MOTOROLA
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