90后嵌入式软件开发生涯 第一篇（am335x LCD 驱动移植）

本文实现一个am35xskevm的uboot开机显示logo

一、从TI官网上下载裸机驱动包StarerWare

二、在rasterDisplay.c的main中找到如下函数做以下修改：

//Enable backlight

LCDBackLightEnable();

//set Lcd

SetUpLCD();

/* Configuring the base ceiling

Configure the base address register with base address of the array which contain pixels of the image to be

displayed and ceiling address register with end address of the same array using API RasterDMAFBConfig()

*/

RasterDMAFBConfig( 0x4830E000,

(unsigned int)image1,

(unsigned int)image1 + sizeof(image1) - 2,

0);

RasterDMAFBConfig( 0x4830E000,

(unsigned int)image1,

(unsigned int)image1 + sizeof(image1) - 2,

1);

/* Enable End of frame0/frame1 interrupt */

RasterIntEnable(0x4830E000,(0x00000100u)|(0x00000200u));

/* Enable raster */

RasterEnable( 0x4830E000);

并找到SetUpLCD()函数。

static void SetUpLCD(void)

{

/* Enable clock for LCD Module */

LCDModuleClkConfig();

/*Pin multiplexing registers to enable LCD raster pin and a standard configuration is provided as part of the

function LCDPinMuxSetup() in platform directory

*/

LCDPinMuxSetup();

/*

**Clock for DMA,LIDD and for Core(which encompasses

** Raster Active Matrix and Passive Matrix logic)

** enabled.

*/

RasterClocksEnable(LCDC_INSTANCE);

/* Disable raster */

RasterDisable(LCDC_INSTANCE);

/* Configure the pclk

Configure the rate at which pixel data should be output by configuring pixel clock frequency by invoking

RasterClkConfig() API

*/

RasterClkConfig(LCDC_INSTANCE, 23040000, 192000000);

/* Configuring DMA of LCD controller

Configuring the DMA for single or double frame buffer ,busrst size for DMA data transfer etc is done by

invoking RasterDMAConfig() API

*/

RasterDMAConfig(LCDC_INSTANCE, 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(LCDC_INSTANCE, RASTER_DISPLAY_MODE_TFT_UNPACKED,

RASTER_PALETTE_DATA, RASTER_COLOR, RASTER_RIGHT_ALIGNED);

/* Configuring the polarity of timing parameters of raster controller for example frame clock , pixel clock, line clock etc.*/

RasterTiming2Configure(LCDC_INSTANCE, RASTER_FRAME_CLOCK_LOW |

RASTER_LINE_CLOCK_LOW |

RASTER_PIXEL_CLOCK_HIGH|

RASTER_SYNC_EDGE_RISING|

RASTER_SYNC_CTRL_ACTIVE|

RASTER_AC_BIAS_HIGH , 0, 255);

/* Configuring horizontal timing parameter */

RasterHparamConfig(LCDC_INSTANCE, 480, 4, 8, 43);

/* Configuring vertical timing parameters */

RasterVparamConfig(LCDC_INSTANCE, 272, 10, 4, 12);

/*Configure the required amount of FIFO delay by invoking RasterFIFODMADelayConfig()*/

RasterFIFODMADelayConfig(LCDC_INSTANCE, 128);

}

以下是SetUpLCD()函数在docs目录下UserGuide_02_00_00_07.pdf中的说明：

Programing Sequence

To program the raster controller, the following sequence can be used.

• Enable clock for LCD module.

• Pin multiplexing registers to enable LCD raster pin and a standard configuration is provided as part of the

function LCDPinMuxSetup() in platform directory

• Enable Software Clock for DMA,LIDD submodule and for Core(which encompasses raster active and

passive matrix logic) by invoking RasterClocksEnable() API.

• Configure the rate at which pixel data should be output by configuring pixel clock frequency by invoking

RasterClkConfig() API.

• Configuring the DMA for single or double frame buffer ,busrst size for DMA data transfer etc is done by

invoking RasterDMAConfig() API.

• Configuring Panel type(TFT or STN) ,color display or monochrome, 1/2/4/8/16/24 bit per pixel mode (packed or

unpacked(only for 24 bit)) is done invoking RasterModeConfig()API.

• Configure the polarity of various timing parameters (for example frame clock , pixel clock, line clock etc.) used

by raster by invoking RasterTiming2Configure()

• Configure the Horizontal timing parameters and pixel per line of the raster by invoking RasterHparamConfig()

API.

• Configure the vertical timing parameters and Pixel per panel of the raster invoking RasterVparamConfigure()

API.

• Configure the required amount of FIFO delay by invoking RasterFIFODMADelayConfig()

• Configure the base address register with base address of the array which contain pixels of the image to be

displayed and ceiling address register with end address of the same array using API RasterDMAFBConfig()

• Enable End of frame 0 and 1 interrupt by invoking RasterIntEnable() API;

• Enable the Raster by inovking RasterEnable()