Epson S1D13504 manual Display Configuration Registers, Display Mode Register, Even Scan Only

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8.2.4	Display Configuration Registers
Display Mode Register
REG[0Dh]										RW
			Simultaneous	Simultaneous	Number Of	Number Of	Number Of
n/a			Display	Display	Bits/Pixel	Bits/Pixel	Bits/Pixel	CRT Enable	LCD Enable
			Option Select	Option Select
					Select Bit 2	Select Bit 1	Select Bit 0
			Bit 1	Bit 0
bits 6-5			Simultaneous Display Option Select Bits [1:0]
			These bits are used to select one of four different simultaneous display mode options: Normal, Line
			Doubling, Interlace, or Even Scan Only. The purpose of these modes is to manipulate the vertical
			resolution of the image so that it fits on both CRT, typically 640 x 480, and LCD. The following
			gives descriptions of the four modes using a 640x480 CRT as an example:
				Table 8-6: Simultaneous Display Option Selection
		Simultaneous Display Option Select Bits [1:0]				Simultaneous Display Option
				00			Normal
				01			Line Doubling
				10			Interlace
				11			Even Scan Only

Note

1.Line doubling option is not supported with dual panel.

2.Dual Panel Considerations

When configured for a dual panel LCD and using Simultaneous Display,

the Half Frame Buffer Disable, REG[1Bh] bit 0, must be set to 1. This will result in a lower contrast on the LCD panel, which then may require adjustment.

Normal - the image is the same on both displays, i.e. 640x240. CRT parameters determine the LCD image. The LCD image will appear to be washed out due to the 1/525 duty cycle of the CRT.

Line Doubling - each line is sent to the CRT twice, giving a 640x480 image which has a long aspect ratio. The image on the LCD has each line sent twice but only one FPLINE. This gives a duty cycle of 2/525, which is very close to the LCD only mode duty cycle of 1/242, so the image on the LCD will have almost the same contrast as that of a single LCD.

Interlace - odd frames receive odd scan lines and even frames receive even scan lines. The 640x480 image on the CRT will be normal while the image on the 640x240 LCD will appear to be squashed, though text will be readable.

Even Scan Only - the 640x480 image on the CRT is normal. The LCD (640x240) only receives the even scan lines. The image on the LCD does not flicker, but it may be hard to read text.

Hardware Functional Specification	S1D13504
Issue Date: 01/01/30	X19A-A-002-18