Epson S1D13705 5.1.1 Registers, 5.1.2 Examples

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S1D13705 Programming Notes and Examples
X27A-G-002-03 Issue Date: 02/01/22
5.1.1 Registers
Memory Address Offset Register
REG[11h] forms an 8-bit value called the Memory Address Offset. This offset is the
number of additional words on each line of th e display. If the offset is set to zero there is
no virtual width.
Note
This value does not represent the number of words to be shown on the display. The dis-
play width is set in the Horizontal Display Width register.
5.1.2 Examples
Example 1:In this example we go through the calculations to display a 640x480 im-
age on a 320x240 panel at 2 bpp.
Step 1: Calculate the number of pixels per word for this color depth.
At 2 bpp each byte is comprised of 4 pixels, therefore each word contains 8 pixels.
pixels_per_word = 16 / bpp = 16 / 2 = 8
Step 2: Calculate the Memory Address Offset register value
We require a total of 640 pixels. The horizontal display register will account for 32 0 pixels,
this leaves 320 pixels for the Memory Address Offset register to account for.
offset = pixels / pixels_per_word = 320 / 8 = 40 = 28h
The Memory Address Offset register, REG[11h], will have to be set to 28h to satisfy the
above condition.
REG[11h] Memory Address Offset Register
Memory
Address
Offset
Bit 7
Memory
Address
Offset
Bit 6
Memory
Address
Offset
Bit 5
Memory
Address
Offset
Bit 4
Memory
Address
Offset
Bit 3
Memory
Address
Offset
Bit 2
Memory
Address
Offset
Bit 1
Memory
Address
Offset
Bit 0