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SDRAM Controller (SDRC) Subsystem
programmed to:
•
Image width = w pixels (that is, w = 13 * 64 /2 = 416)
•
Image height = h pixels (that is, h = 19 * 16 = 304)
NOTE:
In this example, the values obtained are not integer values, but are rounded up to the
closest integer value. This results in a loss of physical memory, generally negligible
compared to the total size of the image.
In terms of memory allocation (in the physical memory), this corresponds to a 416 * 304 * 2 =
252,928-byte buffer.
The physical base address of this buffer must be aligned on a page boundary (in that example, a
1024-byte boundary; that is, the 10 LSBs of the base address must be all zeros). This buffer must be
allocated as a contiguous memory segment.
All these parameters, once determined, must be loaded in the registers of the chosen context (there
are 12 VRFB contexts with 12 independent sets of registers).
Example, context 1:
•
Configure the physical base address of the frame buffer. Example: 512M bytes, start of CS0,
SMS.
[30:0] PHYSICALBA = 0x20000000 (where n = 1)
•
Configure the image height and width:
Image width (416): SMS.
[10:0] IMAGEWIDTH = 0x1A0 (where n = 1)
Image height (304): SMS.
[26:16] IMAGEHEIGHT = 0x130
•
Configure the control parameters:
Pixel size (example: 2 bytes, 2
1
bytes): SMS.
[1:0] PS = 0x1 (where n = 1)
Page (page) size (example: 1024 bytes = 64 bytes * 16 bytes)
Page height (example: 16 rows, 2
4
rows): SMS.
[10:8] PH = 0x4
Page width (example: 64 bytes, 2
6
bytes): SMS.
[6:4] PW = 0x6
3. The frame buffer just created is now ready for use by the different system initiators (MPU, sDMA, DSS
controller, etc.).
From the perspective of these modules, the frame buffer object can be accessed at the following VRFB
address-space memory locations:
•
Context 1 0-degree view: 0x7400 0000
•
Context 1 90-degree view: 0x7500 0000
•
Context 1 180-degree view: 0x7600 0000
•
Context 1 270-degree view: 0x7700 0000
The start address of the view corresponds to the logical origin of the image (x = 0, y = 0). The image
pitch parameter, commonly defined as the distance between two vertically adjacent pixels, is fixed to
2048 pixels.
Example of usage by the application:
In a system using an 400 * 300 LCD panel that has a native landscape orientation, the natural scan
order is as shown in
.
2265
SWPU177N – December 2009 – Revised November 2010
Memory Subsystem
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