EM78808
8-bit Micro-controller
One instruction
REGISTER
IOC7(0) IOC7(1) IOC7(2) IOC7(3) IOC7(4) IOC7(5) IOC7(6) IOC7(7) IOC8(0) IOC8(1) IOC8(2) IOC8(3) IOC8(4) IOC8(5) IOC8(6) IOC8(7)
STROBE
SEG8
SEG9
1
1
1
1
1
1
1
1
1
1
1
0
1
1
1
1
1
1
1
1
1
1
1
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1
1
0
1
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1
0
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1
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0
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0
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0
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SEG10
SEG11
SEG12
SEG13
SEG14
SEG15
SEG16
SEG17
SEG18
SEG19
SEG20
SEG21
SEG22
SEG23
Fig.14 key strobe signal
Bit 6(KEYCHK) : Key check enable control bit
0 ꢂdisable key check function.
1 ꢂenable key check function. SEG8 to SEG23 will keep low level.
Figure 15 is relationship between KEYSCAN, KEYSTROBE , KETCHECK and segments.
And figure 16 is key scan flow by interrupt trigger.
RELATION BETWEEN S(8:23) , KEYSCAN, KEY STROBE, KEY CHECK
KEY SCAN PULSE
KEY SCAN
CONTROL
SEGMENT(8:23)
0
1
0
GND
1
MUX
KEY STROBE SIGNAL
MUX
KEYSTROBE
KEYCHECK
Fig.15 KEYSCAN, KEYSTROBE , KEYCHECK and segments.
Bit 7(CAS) : CALL WAITING decoding output
0/1 ꢂCW data valid / No data
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* This specification is subject to change without notice.
8/1/2004 (V3.1)
27
ELAN [ ELAN MICROELECTRONICS CORP ]
