Texas Instruments TMS320DM648 Video Display Field 1 Image Offset Register VDIMGOFF1, IMGVOFF1

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Video Display Registers

4.12.9 Video Display Field 1 Image Offset Register (VDIMGOFF1)

The video display field 1 image offset register (VDIMGOFF1) defines the field 1 image offset and specifies the starting location of the displayed image relative to the start of the active display.

The image line counter (ILCOUNT) is reset to 1 on the first image line (when FLCOUNT = VBLNKYSTOP1 + IMGVOFF1). If the NV bit is set, ILCOUNT is reset to 1 when FLCOUNT = VBLNKYSTOP1 - IMGVOFF1. Display image pixels are output in field 1 beginning on the line where ILCOUNT = 1. The default output values or blanking values are output during active lines prior to ILCOUNT = 1. For a negative offset, IMGVOFF1 must not be greater than VBLNKYSTOP1. The field 1 active image must not overlap the field 2 active image.

The image pixel counter (IPCOUNT) is reset to 0 at the start of an active line image. Once ILCOUNT = 1, image pixels from the FIFO are output on each line in field 1 beginning when FPCOUNT = IMGHOFF1. If the NH bit is set, IPCOUNT is reset when FPCOUNT = FRMWIDTH - IMGHOFF1. The default output values or blanking values are output during active pixels prior to IMGHOFF1.

The video display field 1 image offset register (VDIMGOFF1) is shown in Figure 4-39and described in Table 4-14.

Figure 4-39. Video Display Field 1 Image Offset Register (VDIMGOFF1)

31	30	28	27	16
NV		Reserved		IMGVOFF1
R/W-0		R-0		R/W-0
15	14	12	11	0
NH		Reserved		IMGHOFF1
R/W-0		R-0		R/W-0

LEGEND: R/W = Read/Write; R = Read only; -n= value after reset

Table 4-14. Video Display Field 1 Image Offset Register (VDIMGOFF1) Field Descriptions

				Description
Bit	field (1)	symval (1)	Value	BT.656 and Y/C Mode	Raw Data Mode
31	NV	OF(value)		Negative vertical image offset enable bit.
		DEFAULT	0		Not used.
		NONE
		NEGOFF	1	Display image window begins before the	Not used.
				first active line of field 1. (Used for VBI
				data output.)
30-28	Reserved	-	0	Reserved. The reserved bit location is always read as 0. A value written to this field
				has no effect.
27-16	IMGVOFF1	OF(value)	0-FFFh	Specifies the display image vertical offset in lines from the first active line of field 1.
		DEFAULT	0
15	NH	OF(value)		Negative horizontal image offset.
		DEFAULT	0		Not used.
		NONE
		NEGOFF	1	Display image window begins before the	Not used.
				start of active video. (Used for HANC
				data output.)
14-12	Reserved	-	0	Reserved. The reserved bit location is always read as 0. A value written to this field
				has no effect.

(1)For CSL implementation, use the notation VP_VDIMGOFF1_field_symval.

132 Video Display Port SPRUEM1 –May 2007

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