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37.5.4.3 Memory Interface

37.5.4.3.1 RGB Mode

The preview datapath contains a data formatter that converts 8:8:8 pixel to RGB 5:6:5 format compliant with the 16-

bit format of the LCD controller

. In general, when converting from a color channel with more bits to one with fewer

bits, the formatter module discards the lower-order bits.

For example, converting from RGB 8:8:8 to RGB 5:6:5, the formatter module discards the three LSBs from the red

and blue channels, and two LSBs from the green channel.

37.5.4.3.2 12-bit Grayscale Mode

ISI_DATA[11:0] is the physical interface to the ISI. These bits are sampled and written to memory.

When 12-bit Grayscale mode is enabled, two memory formats are supported:

ISI_CFG2.GS_MODE = 0: two pixels per word

ISI_CFG2.GS_MODE = 1: one pixel per word

The following tables illustrate the memory mapping for the two formats.

Table 37-8. Grayscale Memory Mapping Configuration for 12-bit Data (ISI_CFG2.GS_MODE = 0: two pixels

per word)

31 30 29 28 27 26 25 24

Pixel 0 [11:4]

23 22 21 20 19 18 17 16

Pixel 0 [3:0] – – – –

15 14 13 12 11 10 9 8

Pixel 1 [11:4]

7 6 5 4 3 2 1 0

Pixel 1 [3:0] – – – –

If ISI_CFG1.GRAYLE = 0, the pixels map as follows:

If ISI_CFG1.GRA

YLE=1, the pixels map as follows:

Table 37-9. Grayscale Memory Mapping Configuration for 12-bit Data (ISI_CFG2.GS_MODE = 0: two pixels