Sharp ER-1910 Service Manual page 6

- LOW
CLI/CL2
ba 500mS
"Power c on.
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Vcc \
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PEIN
RES I
SHEN
~ LDRQ.
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ok :
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SCK
8 clocks ©
Data process by CPU
ER=2395
The CPU (SC1033C) is not operating as'+5V is notin supply during
power off.
(2) When power is turned on.
When the power is turned on, PE is foised high and sent to the
KDC. The KDC having received a ee State of PE, the KDC | issues
RES1. to reset the CPU. |
(3) When power is turned off x 2 ee c o
When the power is turned off, PE is forced low and' directly sent to
the CPU. After the. CPU. finishes executing.the required processing,
it sends LDRQ and SCK to the KDC. leat - send R AEST cue
CPU thus received RES1 is. then: reset. a
Power off
i
(¢——
%§
RES1 generating condition: SCK = low at a low to
_ high transition of LDRQ.
—| @ . Reset is released from the CPU upon detecting the mode and key input.
Fig. 4-13
(4) KDC reset
SRV 2 SRV2--SRV1
' :
RESET
a KDC starts
SCK
Fig. 4-14
~The CPU initializes every ey and reads ine
'start condition.
REST
"2 QV others are high impedance
P21, 380~388, 70~78
(5) Data transfer between the CPU and the KDC ~~
Data is transferred through the CPU and KDC 8-bit serial port in
synchronization. with SCK received from the CPU...
To transfer data from the CPU to the KDC, the STH line is used.
To transfer data from the KDC to the CPU, the HTS line is used.
Data transfer can take place with a SHEN which is an output from
the KDC. When the CPU senses a high state of SHEN, it responds
with SCK to carry out data transfer. When data transfer has been
completed, the CPU sends a.LDRQ to the KDC to inform that the
CPU has finished meen: and sending. |