Epson S1D13705 User Manual download pdf (Page 121)

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Epson Research and Development Page 27

Vancouver Design Center

Programming Notes and Examples S1D13705

Issue Date: 02/01/22 X27A-G-002-03

Example 2: From the above, what is the maximum number of lines our image can

contain?

Step 1: Calculate the number of bytes on each line.

bytes_per_line = pixels_per_line / pixels_per_byte = 640 / 4 = 160

Each line of the display requires 160 bytes.

Step 2: Calculate the number of lines the S1D13705 is capable of.

total_lines = memory / bytes_per_line = 81920 / 160 = 512

We can display a maximum of 512 lines. Our example image requires 480 lines so this

example can be done.

5.2 Panning and Scrolling

Panning and scrolling describe the operation of moving a physical display viewport about

a virtual image in order to view the entire image a portion at time. For example, after setting

up the previous example (virtual display) and drawing an image into it we would only be

able to view one quarter of the image. Panning and scrolling are used to reveal the rest of

the image.

Panning describes the horizontal (side to side) motion of the viewport. When panning to the

right the image in the viewport appears to slide to the left. When panning to the left the

image to appears to slide to the right. Scrolling describes the vertical (up and down) motion

of the viewport. Scrolling down causes the image to appear to slide up and scrolling up

causes the image to appear to slide down.

Both panning and scrolling are performed by modifying the start address register. The start

address registers in the S1D13705 are a word offset to the data to be displayed in the top

left corner of a frame. Changing the start address by one means a change on the display of

the number of pixels in one word. The number of pixels in word varies according to the

color depth. At 1 bit-per-pixel a word contains sixteen pixels. At 2 bit-per-pixel there are

eight pixels, at 4 bit-per-pixel there are four pixels and at 8 bit-per-pixel there is two pixels

in each word. The number of pixels in each word represent the finest step we can pan to the

left or right.

When portrait mode (see Hardware Rotation on page 37) is enabled the start address

registers become offsets to bytes. In this mode the step rate for the start address registers if

halved making for smoother panning.

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Epson S1D13705 User Manual Page 121

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