裸机控制器详解原理程序LCD(裸机控制器引脚寄存器详解)

来源：韦东山嵌入式专栏_ARM裸机加强版维基教程作者：韦东山本文字数：3840，阅读时长：2.5分钟继续上一节的代码，修改s3c2440_lcd_controller.c：

struct lcd_controller s3c2440_lcd_controller = {    .init    = s3c2440_lcd_controller_init,    .enalbe  = s3c2440_lcd_controller_enalbe,    .disable = xs3c2440_lcd_controller_disable,};

然后对每个函数进行功能实现，首先是s3c2440_lcd_controller_init，依次设置LCD控制器寄存器，先是LCD寄存器1：[27:18]为只读数据位，不需要设置；[17:8]用于设置CLKVAL(像素时钟频率)，我们使用的是TFT屏，因此采用的公式是VCLK = HCLK / [(CLKVAL+1) x 2]，其中HCLK为100M
LCD手册里面Clock cycle的要求范围为5-12MHz即可，即假设VCLK=9，根据公式9=100/[(CLKVAL+1)x2],算出CLKVAL≈4.5=5
VCLK为plcdparams->time_seq.vclk，则clkval = HCLK/plcdparams->time_seq.vclk/2-1+0.5;[7]不用管，默认即可；[6:5]TFT lcd配置为0b11；[4:1]设置bpp模式，根据传入的plcdparams->bpp配置为相应的数值；[0]LCD输出使能，先暂时关闭不输出；寄存器2：对比2440LCD部分时序图和LCD时序图，得出两者之间关系，以后就可通过plcdparams传参数进来设置相关寄存器
[31:24] : VBPD = tvb - 1[23:14] : LINEVAL = line - 1[13:6] : VFPD = tvf - 1[5:0] : VSPW = tvp - 1寄存器3：[25:19] : HBPD = thb - 1[18:8] : HOZVAL = 列 - 1[7:0] : HFPD = thf - 1寄存器4：[7:0] : HSPW = thp - 1寄存器5：用来设置引脚极性, 设置16bpp, 设置内存中象素存放的格式[12] : BPP24BL[11] : FRM565, 1-565[10] : INVVCLK, 0 = The video data is fetched at VCLK falling edge[9] : HSYNC是否反转[8] : VSYNC是否反转[7] : INVVD, rgb是否反转[6] : INVVDEN[5] : INVPWREN[4] : INVLEND[3] : PWREN, LCD_PWREN output signal enable/disable[2] : ENLEND[1] : BSWP[0] : HWSWP然后再设置framebuffer地址，先是LCDSADDR1：[29:21] : LCDBANK, A[30:22] of fb[20:0] : LCDBASEU, A[21:1] of fb即用[29:0]表示起始地址的[30:1]
LCDSADDR2：[20:0] : LCDBASEL, A[21:1] of end addr即framebuffer的结束地址
最后还要设置相关引脚，包括背光控制引脚、LCD专用引脚、电源控制引脚：

void jz2440_lcd_pin_init(void){    / 初始化引脚 : 背光引脚 /    GPBCON &= ~0x3;    GPBCON |= 0x01;    / LCD专用引脚 /    GPCCON = 0xaaaaaaaa;    GPDCON = 0xaaaaaaaa;    / PWREN /    GPGCON |= (3<<8);}

LCD所有寄存器的具体设置如下：

#define HCLK 100void jz2440_lcd_pin_init(void){    / 初始化引脚 : 背光引脚 /    GPBCON &= ~0x3;    GPBCON |= 0x01;    / LCD专用引脚 /    GPCCON = 0xaaaaaaaa;    GPDCON = 0xaaaaaaaa;    / PWREN /    GPGCON |= (3<<8);}/ 根据传入的LCD参数设置LCD控制器 /void s3c2440_lcd_controller_init(p_lcd_params plcdparams){    int pixelplace;    unsigned int addr;    jz2440_lcd_pin_init();    / [17:8]: clkval, vclk = HCLK / [(CLKVAL+1) x 2]                        9   = 100M /[(CLKVAL+1) x 2], clkval = 4.5 = 5                      CLKVAL = 100/vclk/2-1      [6:5]: 0b11, tft lcd      [4:1]: bpp mode      [0]  : LCD video output and the logic enable/disable     /    int clkval = (double)HCLK/plcdparams->time_seq.vclk/2-1+0.5;    int bppmode = plcdparams->bpp == 8  ? 0xb :\                  plcdparams->bpp == 16 ? 0xc :\                  0xd;  / 0xd: 24bpp /    LCDCON1 = (clkval<<8) | (3<<5) | (bppmode<<1) ;    / [31:24] : VBPD    = tvb - 1      [23:14] : LINEVAL = line - 1      [13:6]  : VFPD    = tvf - 1      [5:0]   : VSPW    = tvp - 1     /    LCDCON2 =   ((plcdparams->time_seq.tvb - 1)<<24) | \                ((plcdparams->yres - 1)<<14)         | \                ((plcdparams->time_seq.tvf - 1)<<6)  | \                ((plcdparams->time_seq.tvp - 1)<<0);    / [25:19] : HBPD    = thb - 1      [18:8]  : HOZVAL  = 列 - 1      [7:0]   : HFPD    = thf - 1     /    LCDCON3 =   ((plcdparams->time_seq.thb - 1)<<19) | \                ((plcdparams->xres - 1)<<8)           | \                ((plcdparams->time_seq.thf - 1)<<0);    /       [7:0]   : HSPW    = thp - 1     /    LCDCON4 =   ((plcdparams->time_seq.thp - 1)<<0);    / 用来设置引脚极性, 设置16bpp, 设置内存中象素存放的格式      [12] : BPP24BL      [11] : FRM565, 1-565      [10] : INVVCLK, 0 = The video data is fetched at VCLK falling edge      [9]  : HSYNC是否反转      [8]  : VSYNC是否反转      [7]  : INVVD, rgb是否反转      [6]  : INVVDEN      [5]  : INVPWREN      [4]  : INVLEND      [3]  : PWREN, LCD_PWREN output signal enable/disable      [2]  : ENLEND      [1]  : BSWP      [0]  : HWSWP     /    pixelplace = plcdparams->bpp == 24 ? (0) : |\                 plcdparams->bpp == 16 ? (1) : |\                 (1<<1);  / 8bpp /    LCDCON5 = (plcdparams->pins_pol.vclk<<10) |\              (plcdparams->pins_pol.rgb<<7)   |\              (plcdparams->pins_pol.hsync<<9) |\              (plcdparams->pins_pol.vsync<<8) |\              (plcdparams->pins_pol.de<<6)    |\              (plcdparams->pins_pol.pwren<<5) |\              (1<<11) | pixelplace;    / framebuffer地址 /    /      [29:21] : LCDBANK, A[30:22] of fb      [20:0]  : LCDBASEU, A[21:1] of fb     /    addr = plcdparams->fb_base & ~(1<<31);    LCDSADDR1 = (addr >> 1);    /       [20:0] : LCDBASEL, A[21:1] of end addr     /    addr = plcdparams->fb_base + plcdparams->xresplcdparams->yresplcdparams->bpp/8;    addr >>=1;    addr &= 0x1fffff;    LCDSADDR2 = addr;// }void s3c2440_lcd_controller_enalbe(void){    / 背光引脚 : GPB0 /    GPBDAT |= (1<<0);    / pwren    : 给LCD提供AVDD  /    LCDCON5 |= (1<<3);    / LCDCON1'BIT 0 : 设置LCD控制器是否输出信号 /    LCDCON1 |= (1<<0);}void s3c2440_lcd_controller_disable(void){    / 背光引脚 : GPB0 /    GPBDAT &= ~(1<<0);    / pwren    : 给LCD提供AVDD  /    LCDCON5 &= ~(1<<3);    / LCDCON1'BIT 0 : 设置LCD控制器是否输出信号 /    LCDCON1 &= ~(1<<0);}

这就完成了s3c2440_lcd_controller.c的编写，后面只需要向s3c2440_lcd_controller_init()传入构造好的参数即可
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