TVP3020 datasheet(39/98 Pages) TI

39 / 98 page

2–25

(0,0)

(31,31)

(63,63)

Figure 2–7. Common Sprite-Origin Settings

NOTE: The programmable sprite-origin feature can be especially useful in creating

crosshair cursors and pointers. See Section 2.5.5 and Figures 2–8 and 2–9 for

more details.

2.5.4

Crosshair Cursor

Cursor positioning for the crosshair cursor is also done through the cursor-position (x,y) register. The

intersection of the crosshair cursor is specified by the cursor-position (x,y) register. If the thickness of the

crosshair cursor is greater than one pixel, the center of the intersection is the reference position. The

thickness of the crosshair cursor is specified by cursor-control register bits 0 and 1 (see Section 2.16.2).

The sprite-origin (x,y) register has no effect on the crosshair cursor location.

In order to display the crosshair cursor, cursor-control register bit 2 needs to be enabled while CCR bit 3

is used to set the desired color as shown in the following table:

CCR2

CCR3

CROSSHAIR COLOR

Crosshair not displayed

Cursor color 0

Cursor color 1

Cursor-control register bits 0 and 1 specify the crosshair cursor thickness (see Section 2.16.2).

The crosshair cursor is limited to being displayed within a window, which is specified by the window-start

(x,y) and window-stop (x, y) registers. Since the cursor-position (x,y) register must specify a point within the

window boundaries, it is the responsibility of the user software to ensure that the cursor-position (x,y)

relationship between the different window and cursor register specifying regions.

If a full-screen crosshair cursor is desired, the window-start (x,y) registers should contain 0000 (hex) and

the window-stop (x,y) registers should be set to the last pixel location on the active screen. For the crosshair

cursor to be displayed, the window-start and window-stop registers must contain locations on the active

screen. If one wishes to temporarily remove the crosshair cursor from the screen without disabling the

function, the window-start registers can be programmed with a location off the active screen.

TVP3020 Datasheet(PDF) 39 Page - Texas Instruments