ST7735 TFT显示屏 显示问题

1. 叙述

许久未使用的TFT显示屏，这些天突然想使用它来竖屏显示，在查阅数据手册后设置成功，加上还有一些颜色显示问题，一并记录。首先看数据手册的寄存器功能位描述

数据手册

再看一下不同设置方法的理论显示效果

显示分析

由于一开始的色块刷新函数适用于的初始化时(36h)寄存器位置写入的值为(1100_0000),也就是上图的第四个，注意上图的三位数据和(MV MX MY)与实际寄存器顺序不一样

X-Y 坐标交换: 与DDRAM中的正常数据显示模式相比，就是X和Y的数据对调了

X-Mirror: 与DDRAM中正常的模式相比，为X轴对称

Y-Mirror： 与与DDRAM中正常的模式相比，为Y轴对称

至于为啥采用第四种竖屏 显示，而不是正常模式，由于模块正常模式是反着的，不好看。

若是需要改为横屏 显示，而且还能够使用原来的刷屏函数，那就要向寄存器中写入(0110_0000)

三种显示效果如下所示，由于屏幕亮度太高，文字显示不出来。2是正常显示，1是第四种显示，3是横屏显示

至于颜色错乱问题，如红色显示成了蓝色，是由于(36h)寄存器的RGB位被置1了，所以RGB数据被显示成了BGR。

2.代码

初始化的代如下所示，其实就只改了一行。

void Lcd_Init()
{	
	LCD_GPIO_Init();
	Lcd_Reset();

	Lcd_WriteIndex(0x11);//Sleep exit 
	Lcd_DelayMs (120);
	
	//ST7735R Frame Rate
	Lcd_WriteIndex(0xB1); 
	Lcd_WriteData(0x01); Lcd_WriteData(0x2C); Lcd_WriteData(0x2D); 
	Lcd_WriteIndex(0xB2); 
	Lcd_WriteData(0x01); Lcd_WriteData(0x2C); Lcd_WriteData(0x2D); 
	Lcd_WriteIndex(0xB3); 
	Lcd_WriteData(0x01); Lcd_WriteData(0x2C); Lcd_WriteData(0x2D); 
	Lcd_WriteData(0x01); Lcd_WriteData(0x2C); Lcd_WriteData(0x2D); 
	
	Lcd_WriteIndex(0xB4); //Column inversion 
	Lcd_WriteData(0x07); 
	
	//ST7735R Power Sequence
	Lcd_WriteIndex(0xC0); 
	Lcd_WriteData(0xA2); Lcd_WriteData(0x02); Lcd_WriteData(0x84); 
	Lcd_WriteIndex(0xC1); Lcd_WriteData(0xC5); 
	Lcd_WriteIndex(0xC2); 
	Lcd_WriteData(0x0A); Lcd_WriteData(0x00); 
	Lcd_WriteIndex(0xC3); 
	Lcd_WriteData(0x8A); Lcd_WriteData(0x2A); 
	Lcd_WriteIndex(0xC4); 
	Lcd_WriteData(0x8A); Lcd_WriteData(0xEE); 
	
	Lcd_WriteIndex(0xC5); //VCOM 
	Lcd_WriteData(0x0E); 
	
    //屏幕横竖问题未解决    已解决 写入0x60
	Lcd_WriteIndex(0x36); //MX, MY, RGB mode 
	//Lcd_WriteData(0xC0);  //竖屏
    Lcd_WriteData(0x60);    //横屏
	
	//ST7735R Gamma Sequence
	Lcd_WriteIndex(0xe0); 
	Lcd_WriteData(0x0f); Lcd_WriteData(0x1a); 
	Lcd_WriteData(0x0f); Lcd_WriteData(0x18); 
	Lcd_WriteData(0x2f); Lcd_WriteData(0x28); 
	Lcd_WriteData(0x20); Lcd_WriteData(0x22); 
	Lcd_WriteData(0x1f); Lcd_WriteData(0x1b); 
	Lcd_WriteData(0x23); Lcd_WriteData(0x37); Lcd_WriteData(0x00); 
	
	Lcd_WriteData(0x07); 
	Lcd_WriteData(0x02); Lcd_WriteData(0x10); 
	Lcd_WriteIndex(0xe1); 
	Lcd_WriteData(0x0f); Lcd_WriteData(0x1b); 
	Lcd_WriteData(0x0f); Lcd_WriteData(0x17); 
	Lcd_WriteData(0x33); Lcd_WriteData(0x2c); 
	Lcd_WriteData(0x29); Lcd_WriteData(0x2e); 
	Lcd_WriteData(0x30); Lcd_WriteData(0x30); 
	Lcd_WriteData(0x39); Lcd_WriteData(0x3f); 
	Lcd_WriteData(0x00); Lcd_WriteData(0x07); 
	Lcd_WriteData(0x03); Lcd_WriteData(0x10);  
	
	Lcd_WriteIndex(0x2a);
	Lcd_WriteData(0x00);Lcd_WriteData(0x00);
	Lcd_WriteData(0x00);Lcd_WriteData(0x7f);
	Lcd_WriteIndex(0x2b);
	Lcd_WriteData(0x00);Lcd_WriteData(0x00);
	Lcd_WriteData(0x00);Lcd_WriteData(0x9f);
	
	Lcd_WriteIndex(0xF0); //Enable test command  
	Lcd_WriteData(0x01); 
	Lcd_WriteIndex(0xF6); //Disable ram power save mode 
	Lcd_WriteData(0x00); 
	
	Lcd_WriteIndex(0x3A); //65k mode 
	Lcd_WriteData(0x05); 
	
	
	Lcd_WriteIndex(0x29);//Display on
}

//对应的设置显示区代码
void Lcd_SetRegion(u16 x_start,u16 y_start,u16 x_end,u16 y_end)
{

#ifdef USE_DMA
//修改后，为使用DMA 加速SPI2传输数据(刷屏)    
        Lcd_WriteIndex(0x2A);
        Lcd_WriteData16(x_start);
        Lcd_WriteData16(x_end);

        Lcd_WriteIndex(0x2B);
        Lcd_WriteData16(y_start);
        Lcd_WriteData16(x_end);        //采用DMA搬运时需要使用x_end，很奇怪

        Lcd_WriteIndex(0x2C);

#else	
	//正常显示
	Lcd_WriteIndex(0x2a);
	Lcd_WriteData(0x00);
	Lcd_WriteData(x_start);
	Lcd_WriteData(0x00);
	Lcd_WriteData(x_end);

	Lcd_WriteIndex(0x2b);
	Lcd_WriteData(0x00);
	Lcd_WriteData(y_start);
	Lcd_WriteData(0x00);
	Lcd_WriteData(y_end);

	Lcd_WriteIndex(0x2c);

#endif    

}
           

3.总结

本次主要是在使用littvgl 开源GUI显示图片时发现图片显示颜色出现了问题，开始以为是GUI移植过程出了问题，后来在直接操作屏幕显示发现颜色也不对，便找到了相关的数据手册细看了(36h)这一寄存器的说明，最后定位到了初始化的问题上。本人不才，必有疏漏，望指正。

注意！！！

下载资源 UCOSIII+LittleVGL+DMA刷新屏幕 的朋友，会出现颜色显示不对的问题，需要将原来初始化代码中的 Lcd_WriteData(0x68); //横屏 改为 Lcd_WriteData(0x68)

自己上传的资源不允许修改和评论，这也是**操作，抱歉了。