SLAU723A October 2017 – October 2018 MSP432E401Y , MSP432E411Y
For raw formats used in active matrix panels, the palette RAM provides a 12-bpp output, or a color depth of 12 bits (4096 colors per pixel). Data formats of 24 bpp can be stored in packed or unpacked format. In packed format, four 24 bit pixels are stored in 3 contiguous 32-bit words (also called a quad-pixel triplet) in DDR, as show in Figure 20-5.
When using a 24-bit packed format, four consecutive pixels provide three word-aligned accesses for the DMA. If the MSBPPL and PPL bits in the LCDRASTRTIM0 register are programmed to a multiple of 16, then the MSBLPP and LPP bits of the LCDRASTRTIM1 and LCDRASTRTIM2 register must follow a multiple of 16 so the DMA can access the data using word-aligned accesses.
When LCDTFT = 0x1, TFT24UPCK = 0x1 and TFT24 = 0x1 in the LCDRASTRCTL register, a 24bit unpacked format is used. In this mode, each 24-bpp data is stored in a 32-bit word, with the upper 8 bits unused. Figure 20-6 shows the unpacked implementation.
For 24-bpp color components, data is stored in the DDR in B-G-R order with each color representing 8 bits. When the data is transferred to the LCD pixel data bus (LCDDATA[23:0]), the output is transposed such that a portion of the color components are now displayed on LCDDATA [15:0] in RGB565 format. The three least significant bits of the RGB 24-bit data are prepended to RGB565 data on LCDDATA[23:15]. Figure 20-7 shows the transposition of data.