Rastergraf
Programming On-board Devices 3-15
Figure 3-3 Video Display Timing Fields
To change the horizontal frequency:
The horizontal frequency is also known as horizontal refresh or scan rate.
Indications that the horizontal frequency needs to be changed are an
unviewable picture with diagonal lines or no picture at all. Similar
symptoms can be caused by no sync at all, so make sure that the cables are
connected. When the sync is incorrect, the number of diagonal lines is an
indication of how close to the correct horizontal frequency you are: fewer
lines are closer, more lines are farther. Changing the horizontal frequency
will also affect the vertical frequency. Decreasing the horizontal frequency
will generally result in a wider picture.
To change the horizontal position:
To shift the image
left
increase
the horizontal front porch by the same
amount. Perform the converse procedure to move the image to the
right
.
Horizontal Border
Vertical Border
Vertical Border
Horizontal Blank
Horizontal Blank
Horizontal Border
Vertical Blank
Vertical Retrace
Vertical Blank
Horizontal Retrace
Horizontal Total
Horizontal Retrace Start
Horizontal Display End
Horizontal Blanking Start
Active Display Area
Horizontal Retrace End
Horizontal Blanking End
Vertical Display End
Vertical Blanking Start
Vertical Retrace Start
Vertical Retrace End
Vertical Blanking End
Vertical Total
