Sharp PC-1500 - PC-1500 Servicing and Maintenance; PC-1500 Irregular Condition Handling and Reset; PC-1500 Flexible Printed Cable (FPC) Replacement

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5) Timer/cou nter circuit
-
....
0
...,
0
"'
'"l
r
=
(ft
""
-
-
Pin
No .
I
2
3
4
5
P CS C2
PC4 Cl
PC3 CO
PC 1 t-- - -+ -1 STB
Reset
ILSBI
"
...,
0
-
.,
.,
0
>
(")
Yoo
XTALI-----~
~ITt --- ....J l rJ s2. 1 ssKHz
liTAL 0
~ :!:: 1. Ou~lino
>--~ "[__J As shown in the left,
,;. the µPD! 990AC is used
for
the time keeping IC
to co un t hour/minu te/
secondfmonth/day.
2.
M ain fu n ct ion of
µPD 1990AC
Time data is in the
BCD form and i;;judged
by means of compari-
so n. However, day of
week is not used with
this chip and hour is
represented by 24·hour
system.
IMSBI
DIN
9 4 3 2
2 5 2
B
--
Seco nd$ Minutes Hours Day Week Monti\
4
4
I 4
Bits Bits
4 I 4
Bits Bits
4 I 4
Bits Bits
4 4
Bits
Bits Bits
Signal
In/out Description
na
me
C2 In Mode sele ct signal
C2=0
Ci
In Mode select signal
Cl co Mode Da ta In/out mode
co In Mode select signal
0 0 0
Resister hold
0
1 I Registered shirt
I
0
2 Time set
I 1 3 Time re ad
STB In Strobe. Command is latched by the strobe STB.
cs In
Chip
select: disables CLK and STB input and DAT A OUT outpu t by
the
CS input. All input/output are invalid unless CS
is high.
STB
"\_
J
Internal STB (command latch clock)
cs
./
~
CLK
]
)
Internal CLK (40-bit se rial clock)
]
"\_
Internal OE (gate input of DAT OUT)
OE
../
17
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