ADE3800XT datasheet(89/138 Pages) STMICROELECTRONICS

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ADE3800

distribution of the color components. By default, we assume the most frequent setting is +-+ or -+-,

which means FLICKER_CTRL0[2:0] are programmed to either 101 or 010.

A calculation is done after the number of frames programmed in FRAME_CNT_MAX have passed.

With each frame the calculation is performed only on a horizontal portion of the image on all lines.

The size of that horizontal portion (in pixels) is determined by the value programmed in the

HBLOCK_SIZE included in the following formula:

2 ^ (3 + hblock_size)

For calculation of flicker patterns on the whole image, the result of this formula multiplied by

FRAME_CNT_MAX should be equal to the line length (in pixels), although that is not a constraint.

By splitting the image calculation to smaller horizontal portions, the local scores are banked (saved)

at the end of each portion, hence enabling a reverse pattern within a line to be detected. The

smaller that horizontal portion is, the better chance of detecting pattern reversals within a line.

Taking that into account, the smaller the horizontal portion is, the more frames needed to finish the

full image pattern scan. The minimum horizontal portion can be 8 pixels, and the maximum can be

the size of the line. Vertically, the flicker block is defined to have a resolution of 8 lines, so no

programming is needed to define the vertical portion, it banks automatically every 8 lines, and it

goes through all lines every frame.

The free_run/freeze_scores bit FLICKER_CTRL0[4] enables the final calculation to be fed to the

I2C registers. This bit does not regulate all the internal flicker calculation, but only the update of the

I2C registers.

The output results are stored in four 32 bit registers with addresses described in the table. The

higher the score is, the more that pattern is present in the image (each 32 bit register represents 1

pattern). Whichever pattern is detected most, the TCON is advised to cancel the flicker by switching

the pixel polarity which is the opposite of the pattern detected.

The following figure shows all patterns that can be detected by this flicker block.

Figure 17: 8x8 Walsh basis function set

ADE3800XT 数据表(PDF) 89 Page - STMicroelectronics