3线模拟SPI驱动 HX8347 TFT屏

老五家2.8寸屏，3线GPIO模拟SPI驱动

前言

      面对没有定义的屏幕应该如何应对？查丝印吗？屏幕的驱动芯片都小的惊人，想必是不会打上丝印的，所以即使用显微镜观察，也不能直接看到芯片的类型。没有资料的屏幕，应该只能人工从几百个引脚中判断哪个是哪个，进而推断芯片类型，想想就晕。  但大佬们都太厉害了，看看FPC就知道屏幕的接线定义，也许还有其他巧妙的办法吧。一直好奇这种神技是怎么练成的，也尝试自己来猜定义，但发现实在太难，还是拿来主义，做个等等党（等着引脚定义）比较靠谱。

       本文用的屏是2.8寸TFT屏，驱动芯片是HX8347，定义早被大佬分析出来：

        定义有了。但不巧[IM3~0]=1100，只能支持3线SPI+RGB。驱动RGB屏不是单片机的强项。好像STM32F7XX和ESP32 S3是支持RGB，但也只是好像，这两个都价格不菲，手头也没有。

        还是想办法用3线SPI来驱动吧。

---

一、源码

HX8347.h

#ifndef USER_HX8347_H_
#define USER_HX8347_H_


#define X_MAX_PIXEL 240
#define Y_MAX_PIXEL 320

#define RED     0xf800
#define GREEN   0x07e0
#define BLUE    0x001f
#define WHITE   0xffff
#define BLACK   0x0000
#define YELLOW  0xFFE0
#define GRAY0   0xEF7D      //灰色0 3165 00110 001011 00101
#define GRAY1   0x8410          //灰色1      00000 000000 00000
#define GRAY2   0x4208          //灰色2  1111111111011111

#define LCD_CS          GPIO_Pin_0  // CS:PA0
#define LCD_SDA         GPIO_Pin_1  // SDA:PA1
#define LCD_SCL         GPIO_Pin_3  // SCL:PA3
#define LCD_RST         GPIO_Pin_4  // RST:PA4


#define LCD_SCL_SET GPIO_WriteBit(GPIOA, LCD_SCL,Bit_SET)
#define LCD_SDA_SET GPIO_WriteBit(GPIOA, LCD_SDA,Bit_SET)
#define LCD_CS_SET  GPIO_WriteBit(GPIOA, LCD_CS,Bit_SET)
#define LCD_RST_SET GPIO_WriteBit(GPIOA, LCD_RST,Bit_SET)


#define LCD_SCL_CLR GPIO_WriteBit(GPIOA, LCD_SCL,Bit_RESET)
#define LCD_SDA_CLR GPIO_WriteBit(GPIOA, LCD_SDA,Bit_RESET)
#define LCD_CS_CLR  GPIO_WriteBit(GPIOA, LCD_CS,Bit_RESET)
#define LCD_RST_CLR GPIO_WriteBit(GPIOA, LCD_RST,Bit_RESET)


void LCD_GPIO_Init(void);
void Lcd_WriteIndex(unsigned char Index);
void Lcd_WriteData(unsigned char Data);
void LCD_WriteData_16Bit(unsigned int Data);
void Lcd_Write_REG(unsigned char Index,unsigned char Data);
void LCD_Init(void);
void Lcd_Clear(unsigned int Color);
void FillRect(u16 x1, u16 y1, u16 x2, u16 y2, u16 color);

#endif /* USER_HX8347_H_ */

HX8347.c

#include "debug.h"
#include "HX8347.h"


void LCD_GPIO_Init(void)
{
   GPIO_InitTypeDef GPIO_InitStructure = {0};

   RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
   GPIO_InitStructure.GPIO_Pin = LCD_SCL|LCD_SDA|LCD_CS|LCD_RST;
   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
   GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
   GPIO_Init(GPIOA, &GPIO_InitStructure);
}


//向SPI总线传输一个8位数据
void  SPI_WriteData(unsigned char Data)
{
    unsigned char i=0;
    for(i=8;i>0;i--)
    {
      if(Data&0x80)
          LCD_SDA_SET; //输出数据
      else LCD_SDA_CLR;

      LCD_SCL_CLR;
      LCD_SCL_SET;
      Data<<=1;
    }
}

//向液晶屏写一个8位指令
void Lcd_WriteIndex(unsigned char Index)
{
   //SPI 写命令时序开始
   LCD_CS_CLR;
   SPI_WriteData(0x70);
   SPI_WriteData(Index);
   LCD_CS_SET;
}

//向液晶屏写一个8位数据
void Lcd_WriteData(unsigned char Data)
{
   LCD_CS_CLR;

   SPI_WriteData(0x72);
   SPI_WriteData(Data);

   LCD_CS_SET;
}

//向液晶屏写一个16位数据
void LCD_WriteData_16Bit(unsigned int Data)
{
   LCD_CS_CLR;

   SPI_WriteData(0x72);
   SPI_WriteData(Data>>8);
   SPI_WriteData(Data);
   LCD_CS_SET;
}

void Lcd_Write_REG(unsigned char Index,unsigned char Data)
{
    Lcd_WriteIndex(Index);
    Lcd_WriteData(Data);
}

void Lcd_Reset(void)
{
    unsigned int i;
    LCD_RST_CLR;
    Delay_Ms(50);
    LCD_RST_SET;
    Delay_Ms(50);
}





//  set region to paint
void LCD_SetWindow(unsigned int x1,unsigned int y1,unsigned int x2,unsigned int y2)
{

    //SC
    Lcd_Write_REG(0x02,x1>>8);       // Column address start2
    Lcd_Write_REG(0x03,(u8)x1);          // Column address start1
    //EC
    Lcd_Write_REG(0x04,x2>>8);       // Column address end2
    Lcd_Write_REG(0x05,(u8)x2);          // Column address end1
    //SP
    Lcd_Write_REG(0x06,y1>>8);       // Row address start2
    Lcd_Write_REG(0x07,(u8)y1);          // Row address start1
    //EP
    Lcd_Write_REG(0x08,y2>>8);       // Row address end2
    Lcd_Write_REG(0x09,(u8)y2);          // Row address end1
    //写0x22到index register，那么下次send data就会直接被写到graphic ram
    Lcd_WriteIndex(0x22);
}


void FillRect(u16 x1, u16 y1, u16 x2, u16 y2, u16 color)
{
    LCD_SetWindow(x1, y1,x2,y2);
    x2 = x2 - x1 + 1;
    y2 = y2 - y1 + 1;
    for(x1 = x2; x1 != 0 ; x1--)
    {
        for (y1 = y2;y1 != 0 ;y1--)
        {
            LCD_WriteData_16Bit(color);
        }
    }
}

void LCD_Init(void)
{
    LCD_GPIO_Init();
    Lcd_Reset();

    Lcd_Write_REG(0x18,0x88);        //UADJ 75Hz
    Lcd_Write_REG(0x19,0x01);        //OSC_EN='1', start Osc
    //Power Voltage Setting
    Lcd_Write_REG(0x1B,0x1E); //VRH=4.60V
    Lcd_Write_REG(0x1C,0x07); //AP Crosstalk    04
    Lcd_Write_REG(0x1A,0x01); //BT (VGH~15V,VGL~-10V,DDVDH~5V)
    Lcd_Write_REG(0x24,0x38); //VMH 27
    Lcd_Write_REG(0x25,0x5F); //VML
    //VCOM offset
    Lcd_Write_REG(0x23,0x8C); //for Flicker adjust
    Lcd_Write_REG(0x1F,0x88);// GAS=1, VOMG=00, PON=0, DK=1, XDK=0, DVDH_TRI=0, STB=0
    Delay_Ms(5);
    Lcd_Write_REG(0x1F,0x80);// GAS=1, VOMG=00, PON=0, DK=0, XDK=0, DVDH_TRI=0, STB=0
    Delay_Ms(5);
    Lcd_Write_REG(0x1F,0x90);// GAS=1, VOMG=00, PON=1, DK=0, XDK=0, DVDH_TRI=0, STB=0
    Delay_Ms(5);
    Lcd_Write_REG(0x1F,0xD0);// GAS=1, VOMG=10, PON=1, DK=0, XDK=0, DDVDH_TRI=0, STB=0
    Delay_Ms(5);
    //Display ON Setting
    Lcd_Write_REG(0x28,0x38);   //GON=1, DTE=1, D=1000
    Delay_Ms(40);
    Lcd_Write_REG(0x28,0x3C);   //GON=1, DTE=1, D=1100
    Lcd_Write_REG(0x36,0x09);   //REV, BGR
    Lcd_Write_REG(0x17,0x05);  //16BIT/PIXEL

    //Gamma 2.2 Setting
    Lcd_Write_REG(0x40,0x00); //
    Lcd_Write_REG(0x41,0x00); //
    Lcd_Write_REG(0x42,0x00); //
    Lcd_Write_REG(0x43,0x11); //
    Lcd_Write_REG(0x44,0x0e); //
    Lcd_Write_REG(0x45,0x23); //
    Lcd_Write_REG(0x46,0x08); //
    Lcd_Write_REG(0x47,0x53); //
    Lcd_Write_REG(0x48,0x03); //
    Lcd_Write_REG(0x49,0x11); //
    Lcd_Write_REG(0x4A,0x18); //
    Lcd_Write_REG(0x4B,0x1a); //
    Lcd_Write_REG(0x4C,0x16); //
    Lcd_Write_REG(0x50,0x1c); //
    Lcd_Write_REG(0x51,0x31); //
    Lcd_Write_REG(0x52,0x2e); //
    Lcd_Write_REG(0x53,0x3f); //
    Lcd_Write_REG(0x54,0x3f); //
    Lcd_Write_REG(0x55,0x3f); //
    Lcd_Write_REG(0x56,0x2c); //
    Lcd_Write_REG(0x57,0x77); //
    Lcd_Write_REG(0x58,0x09); //
    Lcd_Write_REG(0x59,0x05); //
    Lcd_Write_REG(0x5A,0x07); //
    Lcd_Write_REG(0x5B,0x0e); //
    Lcd_Write_REG(0x5C,0x1c); //
    Lcd_Write_REG(0x5D,0x88); //

  
     Delay_Ms(100);
     FillRect(0, 160, 239, 239, 0xf800 );
}

二、说明

1、LCD初始化是从GITHUB上拷的一段程序，具体是啥意思我也不清楚。试过官方数据手册里的初始化程序，一直不能成功。

2、写寄存器的程序

void Lcd_WriteIndex(unsigned char Index)
{
   LCD_CS_CLR;
   SPI_WriteData(0x70);
   SPI_WriteData(Index);
   LCD_CS_SET;
}

 3、写数据的程序

void Lcd_WriteData(unsigned char Data)
{
   LCD_CS_CLR;
   SPI_WriteData(0x72);
   SPI_WriteData(Data);

   LCD_CS_SET;
}

        上面程序中出现SPI_WriteData(0x70); SPI_WriteData(0x72);统一解释下:

        因为是3线SPI，所以缺少CD(或RS)引线，解决的办法一般是SPI发送数据时第一个bit的值代表CD。这样因为多出了1bit，就需要处理9bit的数据。UC1601就是这样，但是HX8347不是这样。

        下面摘自HX8347的数据手册：

        大概意思就是在发数据前需要发“01110”[ID][RS][RW]，一共是8bit。

        这里ID应该取0。RS取0是写指令，取1是写数据。RW取0，表示写。

        所以写指令就是:01110000=0x70；写数据就是：01110010=0x72。也因此就有了：

        SPI_WriteData(0x70); SPI_WriteData(0x72);

三、总结

1、主控是沁恒家申请的CH32V307的评估板，开发工具是MounRiver。不得不说评估板和开发工具都很完美。评估板留有arduino接口，可以和arduino扩展板链接。MounRiver编译很快，下载烧录更快，基本都是零点几秒。

2、本源码可以直接添加到CH32V307的demo中CH32V307EVT\EVT\EXAM\GPIO\GPIO_Toggle例程中运行。

int main(void)
{
    NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
    SystemCoreClockUpdate();
    Delay_Init();

 

    LCD_Init();
    while(1)
    {
        Delay_Ms(1000);
        FillRect(0, 0, 239, 319, 0x07c0 );
        Delay_Ms(1000);
        FillRect(0, 0, 239, 319, 0x0030 );
        Delay_Ms(1000);
        FillRect(0, 0, 239, 319, 0x0000 );
        Delay_Ms(1000);
        FillRect(0, 0, 239, 319, 0xf800 );
    }
}

3、用的是软件模拟3线SPI，所以帧数很低。以后考虑硬件SPI，或再加DMA，但DMA需要SRAM太大，可能玩不转。

演示用视频