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(2) The horizontal sync frequency measurement:
We use the event counter for calculating how many counts are during a long fixed time, because the
vertical sync period is longer than the horizontal sync period, we can enable the event counter when
the first vertical sync generated and disable the event counter when the next vertical sync
generated, this time, we can get the horizontal sync counts during a vertical sync period.
The formula is Horizontal sync frequency
= FH
= Horizontal sync counts / Vertical sync period
==> Horizontal sync frequency
= Horizontal sync Counts / Vertical sync period
2.3.3.3 Hat are the Valid Key Functions for User
There are Five keys on 7277e control panel. They are "i-key, "Left," "Right," "Enter," and "Exit." The
one, i-key, is for auto calibration function, the others are used for OSD controlling. "Enter" for
entering sub-menu of main menu, "Exit" for escaping to main menu from sub-menu or leaving OSD
menu, and "Left," "Right" for adjusting the bar value.
Except the OSD basic key functions, the user can only press "Right" for brightness adjustment, or
"Left" for contrast adjustment.
2.3.3.4 How to Memorize the Timing and Adjusted Data
The EEPROM of 7277e is 24C08, it has 1024 bytes memory size and communicates with MCU by
two wires of I 2 C bus, one wire is "SCL," the other is "SDA". The MCU send clock and data to
EEPROM to do "Write" function and send clock and receive data from EEPROM to do "Read"
function by these two wires. We define three parts of storage area. One is for the storage of the
factory preset data, another is for saving user adjusted data, the other is for common settings area
where stored the data of the OSD color temperature settings, contrast and brightness value .
2.3.3.5 How to Display the OSD Menu
The OSD IC of 7277e is MC141542 which is developed by vender, it receives the data of the OSD
fonts and attribute what we want to display on the screen from the MCU by 2 wires of
communication, and exports OSD window data and PWM volume to the VIDEO circuit, the block
diagram is shown as below,
MCU(MTV112)
(1)Send data to
RAM for OSD
fonts or attribute.
(2)Send data to
Control registers
for PWM ouput
or OSD window
control.
(H-BLANK,HBNK)
2.3.3.6 How to Execute the Auto Alignment Function
The MCU MTV112 supports the UART function, it has 2 I/O serious ports, one is the receiver, the
other is the transmitter, they are connected with an interface to PC and PC can execute alignment
program by RS232 communication to send the formatted data to the MCU for adjusting any
adjustable parameters of the picture and saving the adjusted values into EEPROM. By this way, we
can get the products with the same quality and reduce the manufacturing time.
2-14
SDA
Shift receiving
SCL
register and decoder.
Control
registers
VSYNC
HSYNC
No Copy/Reproduction Allowed
OSD IC (MC141542)
PWM
output
RAM Fonts
generator
VCO circuit
API Confidential
Output to
the VIDEO circu
ROUT
GOUT
BOUT
FBKGC
7277e Monitor Service Guide
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