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Control Block; Sync. Signal Process; Front Button; I2C Bus Control - NEC FP1355 Service Manual

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Control block

The control block is composed of the following:
Monitor MPU IC101 to process the sync. signals, control the inside of the monitor and commu-
nicate with the external, EEPROM IC104 to memorize the picture adjustment values, I/O ex-
pander IC102 to output CS and V-LIN, etc.

Sync. signal process

When HSYNC or Composite Sync is input from the VIDEO board to the MPU IC101 pin 30 and
VSYNC is input to the MPU IC101 pin 20 the frequency/polarity of SYNC will be discriminated.
Then, HS_OUT will be output from pin 27 for beam deflection and OSD display and VS_OUT
will be output from pin 26 as the polarity POSI.
If SYNC is not input or abnormal SYNC is input, the MPU IC101 will output simulative SYNC.
The frequency of the simulative SYNC is near that of the previously input SYNC.
(Initial values: FH:31kHz and FV:60Hz)

Front button

When any tact switch of SW1X0 to SW1X8 on the front panel is pressed, the voltage of +5V will
be divided with the resistor according to the button.
The signal is converted into the digital value with the A/D converter of the MPU IC101 pin 12
and pin 13 to discriminate which button is pressed.

I2C bus control

The IC control inside the monitor is carried out using pin 36: SCL-I2C, pin 37 and pin 38: SDA-
I2C I2C bus.
The adjustment data corresponding to the input timing is read out from EEPROM and transmit-
ted to each IC. For this I2C bus, the master always works as microcomputer. EEPROM IC104,
deflection processor IC601, OSD-IC IC212, and pre-amplifier IC211 work as slaves, transmit
control data. Each slave address is as mentioned in Table 6.
The MPU IC 101 pin 46 is a write protect signal of EEPROM IC 104. At normal state (when
data is not written onto EEPROM), this signal is HI. When data is written onto EEPROM, this
signal turns to LO.
Deflection processor

Power control

The normal state and power management state are switched according to pin 33 P-OFF signal
and pin 32 P-SUS signal.
"Power save" of the OSD adjustment item is turned to "ON", and the power management is
activated when either H/VSYNC goes out.
In the power management mode, P-OFF+5V is turned OFF by setting pin 33 P-OFF signal at
LOW, other power supplies except +5V and heater are turned OFF by setting pin 32 P-SUS
signal at LOW.
Table 6 Slave address list
Symbol No.
A0(Write) / A1(Read)
78(Write) / 79(Read)
7A(Write) / 7B(Read)
1 - 38


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