Figure 7-3. Compare Range for TMED

255 0

LCD Controller

LB=(PixelValue * Frame#) mod 256 + Offset

19264

Compare Range

(LB+PV) mod 256

128

Either of two matrices may be used for each color, chosen by bits 0, 1, and 14 of the TMED Control Register (TCR, Section 7.6.10). Offsets may be selected for the shading of each color to avoid gray color problems. Although these offset values are panel dependent, the recommended values are listed in Section 7.6.9, with the blue data path being used for monochrome modes. Offsets may also be chosen in the TMED Control Register for shifting the row (horizontal) value, line (vertical) value, and frame number.

Figure 7-4shows the block diagram for TMED. Pixel data (up to 8 bits) enters the module and is sent through the Color Value (CV) generator. Depending on the value of the TCR[TSCS] field, the CV generator rounds off between 0 and 3 of the least-significant bits, creating a new CV. If the original pixel value is 254 or 255, the final data output is set to one. Otherwise, the following occurs:

1.The new CV is sent through the Color Offset Adjuster, where it is used as a lookup into the matrix selected by TCR[COAM].

2.Either the 8-bit output of the chosen matrix or 00h, as selected by TCR[COAE], is added to the appropriate color’s seed register value in register TRGBR to form an offset.

3.This offset is added to the result of the multiplication of the Frame Number and the CV to form the algorithm’s lower boundary (only the lower 8 bits are used).

4.The CV is added to the lower boundary to obtain the upper boundary.

5.Row (line) and column (pixel) counters are combined with beat suppression (offset) values in the Pixel Number Adjuster and Address Generator to form yet another address for a matrix lookup.

6.The output of the chosen matrix is compared to the lower and upper boundaries in the Data Generator.

7.If the matrix output is between these boundaries or the original pixel value is 254 or 255, then the data output to the panel is one. In all other cases, it is zero.

Intel® PXA255 Processor Developer’s Manual

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Intel PXA255 manual Compare Range for Tmed