I8080 8BIT 点亮 240x320 屏

注意芯片型号！

首先确认芯片型号是否为支持型号。

此次适配的 I8080 屏为 D240C2422V0，使用的是 I8080 进行驱动。

引脚配置如下：

V821	引脚复用功能	TFT 模块
PD1—PD8	LCD-D3—LCD-D12	D0—D7
PD12	LCD-VSYNC	TE
PD11	LCD-HSYNC	RD
PD9	LCD-CLK	WR
PD10	LCD-DE	DC
PD14	GPIO OUTPUT	CS
PD19	GPIO OUTPUT	RESET

编写 LCD 显示屏驱动

获取屏幕初始化序列

首先询问屏厂提供初始化序列，和屏幕手册。

屏厂会提供一个初始化代码

RES=1;
Delayms(5);
RES=0;
Delayms(10);
RES=1;
Delayms(120);
//************* Start Initial Sequence **********//
Writecom(0x11);     
Delayms(120);                //ms            
Writecom(0x36);     
Writedat(0x00);   
Writecom(0x3A);     
Writedat(0x55);   
Writecom(0xB2);     
Writedat(0x0C);   
Writedat(0x0C);   
Writedat(0x00);   
Writedat(0x33);   
Writedat(0x33);   
Writecom(0xB7);     
Writedat(0x56);   
Writecom(0xBB);     
Writedat(0x20);   
Writecom(0xC0);     
Writedat(0x2C);   
Writecom(0xC2);     
Writedat(0x01);   
Writecom(0xC3);     
Writedat(0x0F);   
Writecom(0xC4);     
Writedat(0x20);   
Writecom(0xC6);     
Writedat(0x0F);   
Writecom(0xD0);     
Writedat(0xA4);   
Writedat(0xA1);   
Writecom(0xD6);     
Writedat(0xA1);   
Writecom(0xE0);
Writedat(0xF0);
Writedat(0x00);
Writedat(0x06);
Writedat(0x06);
Writedat(0x07);
Writedat(0x05);
Writedat(0x30);
Writedat(0x44);
Writedat(0x48);
Writedat(0x38);
Writedat(0x11);
Writedat(0x10);
Writedat(0x2E);
Writedat(0x34);
Writecom(0xE1);
Writedat(0xF0);
Writedat(0x0A);
Writedat(0x0E);
Writedat(0x0D);
Writedat(0x0B);
Writedat(0x27);
Writedat(0x2F);
Writedat(0x44);
Writedat(0x47);
Writedat(0x35);
Writedat(0x12);
Writedat(0x12);
Writedat(0x2C);
Writedat(0x32);
Writecom(0x21);
Writecom(0x29);

编写屏幕驱动

选择一个现成的 LCD 驱动改写即可，这里选择 st7789v_cpu.c 驱动来修改。

找到初始化序列的部分 static void lcd_panel_st7789v_init(u32 sel, struct disp_panel_para *info)

把原来的初始化序列删除，然后将屏厂提供的初始化序列复制进来。

屏厂函数	LCD框架接口
`Writecom`	`sunxi_lcd_cpu_write_index`
`Writedat`	`sunxi_lcd_cpu_write_data`
`Delayms`	`sunxi_lcd_delay_ms`

配置屏幕使用 TE 模式

由于屏幕支持 TE，这里可以配置使用 TE 模式，参考屏幕驱动 IC 手册，查看 TE 启用的寄存器，或者询问屏厂。针对 ST7789V2 IC 驱动，其开启 TE 的寄存器是 35H

配置 TE 时钟的寄存器是 44H

这里配置启用 TE，并且设置 TE 时钟为60Hz。在初始化中写入启用 TE 功能的如下代码

#if defined(CPU_TRI_MODE)
	/* enable te, mode 0 */
	sunxi_lcd_cpu_write_index(0, 0x35);
	sunxi_lcd_cpu_write_data(0, 0x00);

	sunxi_lcd_cpu_write_index(0, 0x44);
	sunxi_lcd_cpu_write_data(0, 0x00);
	sunxi_lcd_cpu_write_data(0, 0x80);
#endif

配置屏幕开启

针对 i8080 屏幕，还需要写入 21H，29H开显示之后，还需要开启 GRAM 写入，对应寄存器是 2CH，一般屏厂会在初始化中提供，但是也有屏厂初始化中不提供这个指令。

如果出现这样屏幕可以亮但是花屏，且送显示没有反应的情况（如下图）

可以尝试增加开启 GRAM 写入的指令到初始化序列最后一行：

sunxi_lcd_cpu_write_index(0, 0x2c);

完整屏幕驱动

完整的屏幕驱动如下：

#include "st7789v_cpu.h"

#define CPU_TRI_MODE

#define DBG_INFO(format, args...)                                              \
	(printk("[ST7789V LCD INFO] LINE:%04d-->%s:" format, __LINE__,         \
		__func__, ##args))
#define DBG_ERR(format, args...)                                               \
	(printk("[ST7789V LCD ERR] LINE:%04d-->%s:" format, __LINE__,          \
		__func__, ##args))
#define panel_reset(val) sunxi_lcd_gpio_set_value(sel, 0, val)
#define lcd_cs(val) sunxi_lcd_gpio_set_value(sel, 1, val)

static void lcd_panel_st7789v_init(u32 sel, struct disp_panel_para *info);
static void LCD_power_on(u32 sel);
static void LCD_power_off(u32 sel);
static void LCD_bl_open(u32 sel);
static void LCD_bl_close(u32 sel);

static void LCD_panel_init(u32 sel);
static void LCD_panel_exit(u32 sel);

static void LCD_cfg_panel_info(struct panel_extend_para *info)
{
#if defined(__DISP_TEMP_CODE__)
	u32 i = 0, j = 0;
	u32 items;
	u8 lcd_gamma_tbl[][2] = {
		/* {input value, corrected value} */
		{ 0, 0 },     { 15, 15 },   { 30, 30 },	  { 45, 45 },
		{ 60, 60 },   { 75, 75 },   { 90, 90 },	  { 105, 105 },
		{ 120, 120 }, { 135, 135 }, { 150, 150 }, { 165, 165 },
		{ 180, 180 }, { 195, 195 }, { 210, 210 }, { 225, 225 },
		{ 240, 240 }, { 255, 255 },
	};

	u32 lcd_cmap_tbl[2][3][4] = {
		{
			{ LCD_CMAP_G0, LCD_CMAP_B1, LCD_CMAP_G2, LCD_CMAP_B3 },
			{ LCD_CMAP_B0, LCD_CMAP_R1, LCD_CMAP_B2, LCD_CMAP_R3 },
			{ LCD_CMAP_R0, LCD_CMAP_G1, LCD_CMAP_R2, LCD_CMAP_G3 },
		},
		{
			{ LCD_CMAP_B3, LCD_CMAP_G2, LCD_CMAP_B1, LCD_CMAP_G0 },
			{ LCD_CMAP_R3, LCD_CMAP_B2, LCD_CMAP_R1, LCD_CMAP_B0 },
			{ LCD_CMAP_G3, LCD_CMAP_R2, LCD_CMAP_G1, LCD_CMAP_R0 },
		},
	};

	items = sizeof(lcd_gamma_tbl) / 2;
	for (i = 0; i < items - 1; i++) {
		u32 num = lcd_gamma_tbl[i + 1][0] - lcd_gamma_tbl[i][0];

		for (j = 0; j < num; j++) {
			u32 value = 0;

			value = lcd_gamma_tbl[i][1] +
				((lcd_gamma_tbl[i + 1][1] -
				lcd_gamma_tbl[i][1]) *
				j) / num;
			info->lcd_gamma_tbl[lcd_gamma_tbl[i][0] + j] =
				(value << 16) + (value << 8) + value;
		}
	}
	info->lcd_gamma_tbl[255] = (lcd_gamma_tbl[items - 1][1] << 16) +
				(lcd_gamma_tbl[items - 1][1] << 8) +
				lcd_gamma_tbl[items - 1][1];

	memcpy(info->lcd_cmap_tbl, lcd_cmap_tbl, sizeof(lcd_cmap_tbl));
#endif
}

static s32 LCD_open_flow(u32 sel)
{
	LCD_OPEN_FUNC(sel, LCD_power_on, 120);
#ifdef CPU_TRI_MODE
	LCD_OPEN_FUNC(sel, LCD_panel_init, 100);
	LCD_OPEN_FUNC(sel, sunxi_lcd_tcon_enable, 50);
#else
	LCD_OPEN_FUNC(sel, sunxi_lcd_tcon_enable, 100);
	LCD_OPEN_FUNC(sel, LCD_panel_init, 50);
#endif
	LCD_OPEN_FUNC(sel, LCD_bl_open, 0);

	return 0;
}

static s32 LCD_close_flow(u32 sel)
{
	LCD_CLOSE_FUNC(sel, LCD_bl_close, 20);
#ifdef CPU_TRI_MODE
	LCD_CLOSE_FUNC(sel, sunxi_lcd_tcon_disable, 10);
	LCD_CLOSE_FUNC(sel, LCD_panel_exit, 50);
#else
	LCD_CLOSE_FUNC(sel, LCD_panel_exit, 10);
	LCD_CLOSE_FUNC(sel, sunxi_lcd_tcon_disable, 10);
#endif
	LCD_CLOSE_FUNC(sel, LCD_power_off, 0);

	return 0;
}

static void LCD_power_on(u32 sel)
{
	/* config lcd_power pin to open lcd power0 */
	sunxi_lcd_power_enable(sel, 0);
	sunxi_lcd_pin_cfg(sel, 1);
}

static void LCD_power_off(u32 sel)
{
	/* lcd_cs, active low */
	lcd_cs(1);
	sunxi_lcd_delay_ms(10);
	/* lcd_rst, active hight */
	panel_reset(1);
	sunxi_lcd_delay_ms(10);

	sunxi_lcd_pin_cfg(sel, 0);
	/* config lcd_power pin to close lcd power0 */
	sunxi_lcd_power_disable(sel, 0);
}

static void LCD_bl_open(u32 sel)
{
	sunxi_lcd_pwm_enable(sel);
	/* config lcd_bl_en pin to open lcd backlight */
	sunxi_lcd_backlight_enable(sel);
}

static void LCD_bl_close(u32 sel)
{
	/* config lcd_bl_en pin to close lcd backlight */
	sunxi_lcd_backlight_disable(sel);
	sunxi_lcd_pwm_disable(sel);
}

/* static int bootup_flag = 0; */
static void LCD_panel_init(u32 sel)
{
	struct disp_panel_para *info =
		kmalloc(sizeof(struct disp_panel_para), GFP_KERNEL);

	DBG_INFO("\n");
	bsp_disp_get_panel_info(sel, info);
	lcd_panel_st7789v_init(sel, info);

	kfree(info);
	return;
}

static void LCD_panel_exit(u32 sel)
{
	sunxi_lcd_cpu_write_index(0, 0x28);
	sunxi_lcd_cpu_write_index(0, 0x10);
}

static void lcd_panel_st7789v_init(u32 sel, struct disp_panel_para *info)
{
	DBG_INFO("\n");
	/* lcd_cs, active low */
	lcd_cs(0);
	sunxi_lcd_delay_ms(10);
	panel_reset(1);
	sunxi_lcd_delay_ms(20);
	panel_reset(0);
	sunxi_lcd_delay_ms(20);
	panel_reset(1);
	sunxi_lcd_delay_ms(120);
	sunxi_lcd_cpu_write_index(0, 0x11);
	sunxi_lcd_delay_ms(120);
	sunxi_lcd_cpu_write_index(0, 0x36);
	sunxi_lcd_cpu_write_data(0, 0x00);

	sunxi_lcd_cpu_write_index(0, 0x3A);
	sunxi_lcd_cpu_write_data(0, 0x55);

	sunxi_lcd_cpu_write_index(0, 0xB2);
	sunxi_lcd_cpu_write_data(0, 0x0C);
	sunxi_lcd_cpu_write_data(0, 0x0C);
	sunxi_lcd_cpu_write_data(0, 0x00);
	sunxi_lcd_cpu_write_data(0, 0x33);
	sunxi_lcd_cpu_write_data(0, 0x33);

	sunxi_lcd_cpu_write_index(0, 0xB7);
	sunxi_lcd_cpu_write_data(0, 0x56);

	sunxi_lcd_cpu_write_index(0, 0xBB);
	sunxi_lcd_cpu_write_data(0, 0x20);

	sunxi_lcd_cpu_write_index(0, 0xC0);
	sunxi_lcd_cpu_write_data(0, 0x2C);

	sunxi_lcd_cpu_write_index(0, 0xC2);
	sunxi_lcd_cpu_write_data(0, 0x01);

	sunxi_lcd_cpu_write_index(0, 0xC3);
	sunxi_lcd_cpu_write_data(0, 0x0F);

	sunxi_lcd_cpu_write_index(0, 0xC4);
	sunxi_lcd_cpu_write_data(0, 0x20);

	sunxi_lcd_cpu_write_index(0, 0xC6);
	sunxi_lcd_cpu_write_data(0, 0x0F);

	sunxi_lcd_cpu_write_index(0, 0xD0);
	sunxi_lcd_cpu_write_data(0, 0xA4);
	sunxi_lcd_cpu_write_data(0, 0xA1);

	sunxi_lcd_cpu_write_index(0, 0xD6);
	sunxi_lcd_cpu_write_data(0, 0xA1);

	sunxi_lcd_cpu_write_index(0, 0xE0);
	sunxi_lcd_cpu_write_data(0, 0xF0);
	sunxi_lcd_cpu_write_data(0, 0x00);
	sunxi_lcd_cpu_write_data(0, 0x06);
	sunxi_lcd_cpu_write_data(0, 0x06);
	sunxi_lcd_cpu_write_data(0, 0x07);
	sunxi_lcd_cpu_write_data(0, 0x05);
	sunxi_lcd_cpu_write_data(0, 0x30);
	sunxi_lcd_cpu_write_data(0, 0x44);
	sunxi_lcd_cpu_write_data(0, 0x48);
	sunxi_lcd_cpu_write_data(0, 0x38);
	sunxi_lcd_cpu_write_data(0, 0x11);
	sunxi_lcd_cpu_write_data(0, 0x10);
	sunxi_lcd_cpu_write_data(0, 0x2E);
	sunxi_lcd_cpu_write_data(0, 0x34);

	sunxi_lcd_cpu_write_index(0, 0xE1);
	sunxi_lcd_cpu_write_data(0, 0xF0);
	sunxi_lcd_cpu_write_data(0, 0x0A);
	sunxi_lcd_cpu_write_data(0, 0x0E);
	sunxi_lcd_cpu_write_data(0, 0x0D);
	sunxi_lcd_cpu_write_data(0, 0x0B);
	sunxi_lcd_cpu_write_data(0, 0x27);
	sunxi_lcd_cpu_write_data(0, 0x2F);
	sunxi_lcd_cpu_write_data(0, 0x44);
	sunxi_lcd_cpu_write_data(0, 0x47);
	sunxi_lcd_cpu_write_data(0, 0x35);
	sunxi_lcd_cpu_write_data(0, 0x12);
	sunxi_lcd_cpu_write_data(0, 0x12);
	sunxi_lcd_cpu_write_data(0, 0x2C);
	sunxi_lcd_cpu_write_data(0, 0x32);

#if defined(CPU_TRI_MODE)
	/* enable te, mode 0 */
	sunxi_lcd_cpu_write_index(0, 0x35);
	sunxi_lcd_cpu_write_data(0, 0x00);

	sunxi_lcd_cpu_write_index(0, 0x44);
	sunxi_lcd_cpu_write_data(0, 0x00);
	sunxi_lcd_cpu_write_data(0, 0x80);
#endif

	sunxi_lcd_cpu_write_index(0, 0x21);
	sunxi_lcd_cpu_write_index(0, 0x29);
	sunxi_lcd_cpu_write_index(0, 0x2c);
}

/* panel driver name, must mach the name of lcd_drv_name in sys_config.fex */
struct __lcd_panel st7789v_cpu_panel = {
	.name = "st7789v_cpu",
	.func = {
		.cfg_panel_info = LCD_cfg_panel_info,
		.cfg_open_flow = LCD_open_flow,
		.cfg_close_flow = LCD_close_flow,
	},
};

配置屏幕驱动

进入内核，勾选 ST7789V_CPU 驱动。

编辑设备树，配置屏幕时序与引脚

&disp {
	disp_init_enable         = <1>;
	disp_mode                = <0>;

	screen0_output_type      = <1>;
	screen0_output_mode      = <4>;
	screen0_to_lcd_index     = <0>;

	screen1_output_type      = <3>;
	screen1_output_mode      = <10>;
	screen1_to_lcd_index     = <2>;

	screen1_output_format    = <0>;
	screen1_output_bits      = <0>;
	screen1_output_eotf      = <4>;
	screen1_output_cs        = <257>;
	screen1_output_dvi_hdmi  = <2>;
	screen1_output_range     = <2>;
	screen1_output_scan      = <0>;
	screen1_output_aspect_ratio = <8>;

	fb_format                = <0>;
	fb_num                   = <1>;
	fb_debug                 = <0>;
	/*<disp channel layer zorder>*/
	fb0_map                  = <0 0 0 16>;
	fb0_width                = <240>;
	fb0_height               = <320>;
	/*<disp channel layer zorder>*/
	fb1_map                  = <0 2 0 16>;
	fb1_width                = <300>;
	fb1_height               = <300>;
	/*<disp channel layer zorder>*/
	fb2_map                  = <1 0 0 16>;
	fb2_width                = <1280>;
	fb2_height               = <720>;
	/*<disp channel layer zorder>*/
	fb3_map                  = <1 1 0 16>;
	fb3_width                = <300>;
	fb3_height               = <300>;

	chn_cfg_mode             = <1>;
	disp_para_zone           = <1>;
};

&lcd0 {
	lcd_used            = <1>;

	lcd_driver_name     = "st7789v_cpu";
	lcd_if              = <1>;

	lcd_x               = <240>;
	lcd_y               = <320>;
	lcd_width           = <43>;
	lcd_height          = <63>;

	lcd_dclk_freq       = <20>;

	lcd_hbp             = <20>;
	lcd_ht              = <298>;
	lcd_hspw            = <10>;
	lcd_vbp             = <8>;
	lcd_vt              = <336>;
	lcd_vspw            = <2>;

	lcd_backlight       = <50>;
	lcd_pwm_used        = <1>;
	lcd_pwm_ch          = <4>;
	lcd_pwm_freq        = <50000>;
	lcd_pwm_pol         = <1>;
	lcd_pwm_max_limit   = <255>;
	lcd_bright_curve_en = <1>;

	lcd_frm             = <2>;
	lcd_gamma_en        = <0>;
	lcd_bright_curve_en = <0>;
	lcd_cmap_en         = <0>;

	lcdgamma4iep        = <22>;
	lcd_cpu_mode        = <1>;
	lcd_cpu_te          = <2>;
	lcd_cpu_if          = <14>;

	/* rst */
	lcd_gpio_0          = <&pio PD 19 GPIO_ACTIVE_LOW>;
	/* cs */
	lcd_gpio_1          = <&pio PD 14 GPIO_ACTIVE_LOW>;

	pinctrl-0 = <&rgb8_pins_a>, <&rgb8_pins_ctl_a>;
	pinctrl-1 = <&rgb8_pins_b>, <&rgb8_pins_ctl_b>;
};

测试屏幕

使用命令查看 TCON 彩条，这个彩条是由 TCON 发出的，操作更加底层。

echo 1 > /sys/class/disp/disp/attr/colorbar

使用命令查看 DE 彩条，这个彩条是由 DE 合成发出的，如果 DE 出问题则可以看到 TCON 彩条看不到 DE 彩条。

提示

如果刚才开了 TCON 彩条，记得先关一下，TCON 彩条优先级更高

echo 0 > /sys/class/disp/disp/attr/colorbar

echo 8 > /sys/class/disp/disp/attr/colorbar

FAQ

I8080接口显示抖动有花纹

改大时钟管脚的管脚驱动能力，改大。

黑屏无显示

黑屏，没有屏幕信号输出

注意芯片型号！

首先确认芯片型号是否为 V821L2-WXX，其他型号不支持 I8080 显示。

完全黑屏，背光也没有

屏驱动添加失败。驱动没有加载屏驱动，导致背光电源相关函数没有运行到。
屏驱动加载成功，但是没有执行到开背光函数（可以在uboot的屏驱动中加打印确认开屏流程的执行情况）。这时候大概率是屏驱动的开屏函数没有执行完，uboot就执行完毕进入内核了。需要在满足屏手册上电时序要求的情况下，尽量减少延迟。
PWM 配置和背光电路的问题，另外就是直接测量下硬件测量下相关管脚和电压，再检查屏是否初始化成功。

黑屏但是有背光

没送图层。如果应用没有送任何图层那么表现的现象就是黑屏。
SoC端的显示接口模块没有供电。SoC端模块没有供电自然无法传输视频信号到屏上。
复位脚没有复位。如果有复位脚，请确保硬件连接正确，确保复位脚的复位操作有放到屏驱动中。
board.dts 中 lcd0有严重错误。第一个是 lcd的timing搞错了，请严格按照屏手册中的提示来写。第二个就是，接口类型搞错。
屏的初始化命令不对。包括各个步骤先后顺序，延时等，这个时候请找屏厂确认初始化命令。

编写 LCD 显示屏驱动​

获取屏幕初始化序列​

编写屏幕驱动​

配置屏幕使用 TE 模式​

配置屏幕开启​

完整屏幕驱动​

配置屏幕驱动​

测试屏幕​

FAQ​

I8080接口显示抖动有花纹​

黑屏无显示​

黑屏，没有屏幕信号输出​

完全黑屏，背光也没有​

黑屏但是有背光​