E 2 Prom For Pnp; E 2 Prom; Cpu Circuit; Dection Of Power Switch Status - HP VF15 Service Manual

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8. E PROM for PnP (Circuit diagram MAIN PWB 3/7)
Data transfer between I308 and host.
There are two forms of communications protocal. In both, display capabilities are retrieved by the system software
during the boot-up and configuration time.
For the PC platform, this software layer is defined in the VESA BIOS Extension / Display Data Channel, DDC2,
standard.
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9. E PROM (Circuit diagram MAIN PWB 4/7)
Data transfer between I306 (24LC16B) and I303 (Circuit diagram MAIN PWB page 4/7 (I306) is effected through the
IIC bus SCL (pin 52) and SDA (pin 51) of I303. The data to be transferred to each device are stored in I306.
l
I303 control data.
l
OSD related setting data.
l Other control data for service menu.
10. CPU circuit (Circuit diagram MAIN PWB 4/7)
I303 (gm2115) embeded microcontroller with parallel ROM interface (I302).
The source voltage for the device is 3.3V and 2.5Vthe system clock frequency is 14.318MHz.
10.1 Detection of POWER switch status
The I303 identifies the ON status of the two power supplies. The identification is made when the power supply is
turned off. For example, if the power supply is turned off with the POWER switch, the POWER switch must be
turned on when activating the power supply again. If the power supply is turned off by pulling out the power
cord, then this power supply can be turned on by connecting the power cord, without pressing the POWER
switch.

10.2 Display mode identification

10.2.1Functions
(1) Display mode identification
l The display mode of input signal is identified based on Table 1, and according to the frequency and polarity
(HPOL, VPOL) of horizontal or vertical sync signal, presence of the resolution or vertical sync signal, and the
discrimination signal (HSYNC_DETECT, VSYNC_DETECT).
l
When the mode has been identified through the measurement of horizontal and vertical frequencies, the total
number of lines is determined with a formula of " Horizontal frequency / Vertical frequency = Total number
of lines. "Final identification can be made by examining the coincidence of the obtained figure with the
number of lines for the mode identified from the frequency.
l
When the detected frequency if the sync signal has changed, the total number of lines should be counted even
through it is registor identified frequency in the same mode. Then, it is necessary to examine whether the
preset value for the vertical display position has exceeded the total number of lines. If exceeded, a maximum
value should be set up, which does not exceed the vertical display position.
(2) Out-of -range
This out-of-range mode is assumed when the frequency of the vertical signal is as specified below.
l Vertical frequency equal to 85Hz into fail save mode.
l
Vertical frequency over 85Hz into out of range.
(3) Power save mode
The power save mode is assumed when the horizontal / vertical signals are as specified below.
l
If there is no horizontal sync signal input.
l If there is no vertical sync signal input.
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