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omapl138 lcd monochrome mode

Other Parts Discussed in Thread: OMAPL138

omapl138 lcd if it is color data, it is encoded as 4 bits(Red), 4 bits(Green), and 4 bits (Blue), and the palette

is RGB444. When it is monochrome data, the pixels data is the index of palette entry, and the palette format

is only 4 bits Mono, what's the real format of pix data after fetching from palette entry? Can someone give

me  explained in detail or example?

  • Hi user4529167,

    By any chance you looked into the configuration-code snippet extracted from file, "demoraster.c" and raster.h of OMAPL138 starterware package ??

    void Raster0Init(void)
    {
        PSCModuleControl(SOC_PSC_1_REGS, HW_PSC_LCDC, PSC_POWERDOMAIN_ALWAYS_ON,
    		     PSC_MDCTL_NEXT_ENABLE);
    
        LCDPinMuxSetup();
    
        /* disable raster */
        RasterDisable(SOC_LCDC_0_REGS);
        
        /* configure the pclk */
        RasterClkConfig(SOC_LCDC_0_REGS, 25000000, 150000000);
    
        /* configuring DMA of LCD controller */ 
        RasterDMAConfig(SOC_LCDC_0_REGS, RASTER_DOUBLE_FRAME_BUFFER,
                        RASTER_BURST_SIZE_16, RASTER_FIFO_THRESHOLD_8,
                        RASTER_BIG_ENDIAN_DISABLE);
    
        /* configuring modes(ex:tft or stn,color or monochrome etc) for raster controller */
        RasterModeConfig(SOC_LCDC_0_REGS, RASTER_DISPLAY_MODE_TFT,
                         RASTER_PALETTE_DATA, RASTER_COLOR, RASTER_RIGHT_ALIGNED);
    
        /* frame buffer data is ordered from least to Most significant bye */
        RasterLSBDataOrderSelect(SOC_LCDC_0_REGS);
        
        /* disable nibble mode */
        RasterNibbleModeDisable(SOC_LCDC_0_REGS);
       
         /* configuring the polarity of timing parameters of raster controller */
        RasterTiming2Configure(SOC_LCDC_0_REGS, RASTER_FRAME_CLOCK_LOW |
                                                RASTER_LINE_CLOCK_LOW  |
                                                RASTER_PIXEL_CLOCK_LOW |
                                                RASTER_SYNC_EDGE_RISING|
                                                RASTER_SYNC_CTRL_ACTIVE|
                                                RASTER_AC_BIAS_HIGH     , 0, 255);
    
        /* configuring horizontal timing parameter */
       RasterHparamConfig(SOC_LCDC_0_REGS, 640, 64, 48, 48);
    
        /* configuring vertical timing parameters */
       RasterVparamConfig(SOC_LCDC_0_REGS, 480, 2, 11, 31);
    
       /* configuring fifo delay to */
       RasterFIFODMADelayConfig(SOC_LCDC_0_REGS, 2);
    }
  • Yes, in StarterWare the example "raster_armv5_omapl138_evmOMAPL138" used 16 BPP RGB565 mode, but what's the format of MONOCHROME mode?
  • Hi,

    Usually a palette entry would be selected from the look-up palette by the pixel data and once it is selected, it's contents would be sent to the gray-scaler/serializer and If it is monochrome data, it would be encoded as 4 bits passive (STN) mode.

    These 4-bit values would be used to select one of the 16 intensity levels, as shown in Table 24-7, section 24.2.5.4.1 in the OMAPl138 TRM as below. A patented algorithm would be used during this processing to provide an optimized intensity value that matches the eye's

    visual perception of color/gray gradations.

    For more details, please refer entry palette/frame buffer format (1,2,4, 12,16 BPP) in sections 24.2.5.1 & 24.2.5.2 from omapl138 TRM below:

    http://www.ti.com/lit/ug/spruh77a/spruh77a.pdf

    Thanks & regards,

    Sivaraj K

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