Circuit Description; Micro Controller Circuit - Tatung VM9G5DA S995T Service Manual

Colour monitor flat screen

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MICRO Controller

The IC101 contains a 6502 8-bit CPU code, 256 bytes of RAM, 16K bytes of ROM, 14 channel 8 bit PWM D/A converters,

2 channel A/D converters for key detection, one 8 bit pre-laudable base timer, internal H-sync and V-sync signals processor

providing mode detection, watch- dog timer preventing system from abnormal operation, and an I2C bus interface.

When CPU detects a timing, it takes relative data from E²PROM (IC102), then output voltage to control the geometry and

video R.G. B drive & bias to make the display best. If key is pressed, the CPU will do some jobs according to the key

function.

H/V sync signals processor

The functions of the sync processor include polarity detection, H-SYNC & V-SYNC signals counting, Programmable

SYNC signals output, free running signal generator. Pin39/Pin40 are for the H-SYNC and V-SYNC input, Pin32/Pin33 will

output the same signal as input sync signal without delay, and the polarity are setting in the positive. When no signal input,

the Pin32 will output a 61HZ V-SYNC free run signal, The Pin33 will output a 62.5KHz H-SYNC free run signal, For the

monitor testing use.

On Screen Display Controller

The IC103 is designed for display the built-in characters or fonts onto monitor screen. The display operation is by

transforming data and control information from micro controller to RAM through a serial data interface.

Pin2 is used to control the internal oscillator frequency by DC voltage input from external low pass filter and filter is used to

regulate the appropriate bias current for internal oscillator the resonate at specific dot frequency.

Pin5 is input the horizontal fly back pulse, for PLL generator tracking.

Pin6 is left floating, I2C bus is enabled. Otherwise the SPI bus is enabled.

Pin7 the external data transfer through this pin to internal display registers and control registers

Pin8 the clock-input pin is used to synchronize the data transfer.

Pin10 is input the vertical flyback pulse for synchronizing the vertical position.

Pin12 is output a blanking signal to cut off external R.G.B signals of VGA while this chip is displaying characters or

windows.

Pin13, Pin14, Pin15 is used to output the OSD (B.G.R) video signal.

5. CIRCUIT DESCRIPTION

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