最近在使用5寸LCD做一个项目。显示功能简单，但要求字体足够醒目。所以采用了256*128超大字体。使用PCtoLCD2002软件取模显示后发现字体刷新速度很慢，甚至眼睛可以看到刷新过程。我用的STM32F103,主频可达到72MHz,LCD 分辨率为800*480,而且使用的FSMC方式显示，理论上刷新频率应该能达到150帧/s( 72M/800/480 ),现在只是显示几个256*128 数字，不应该这么慢。经过最近的研究和调试，终于把速度提上去了。方式如下：
1.修改字体显示驱动程序
此方式是提高速度最重要的方式。之前LCD厂家给的驱动底层循环操作繁琐，执行效率太低，其原始代码如下：
void LCD_ShowChar(u16 x,u16 y,u8 num,u8 size,u8 mode)
{
u8 temp,t1,t;
u16 z=0;
u16 x0=x;
u16 colortemp=POINT_COLOR;
u16 qyt=0;
num=num-' ';//µÃµ½Æ«ÒƺóµÄÖµ
if(size==16)
{
qyt=16;
}else
{
qyt=64; //·ÖΪÁ½ÁÐÏÔʾ£¬¹ÊΪ32*2
}
z=num;
z*=qyt;
//ÉèÖô°¿Ú
if(!mode) //·Çµþ¼Ó·½Ê½
{
for(t=0;t<qyt;t++)
{
if(size==16)
{
temp=asc1608[z]; //µ÷ÓÃ1608×ÖÌå
}else
{
temp=asc3216[z]; //µ÷ÓÃ3216×ÖÌå
}
z++;
for(t1=0;t1<8;t1++)
{
if(temp&0x01)POINT_COLOR=colortemp;
else POINT_COLOR=BACK_COLOR;
LCD_DrawPoint(x,y);
temp>>=1;
x++;
if(x>=lcddev.width){POINT_COLOR=colortemp;return;}//³¬ÇøÓòÁË
if((x-x0)==(size/2))
{
x=x0;
y++;
if(y>=lcddev.height){POINT_COLOR=colortemp;return;}//³¬ÇøÓòÁË
break;
}
}
}
}else//µþ¼Ó·½Ê½
{
for(t=0;t<qyt;t++)
{
if(size==16)
{
temp=asc1608[z]; //µ÷ÓÃ1608×ÖÌå
}else
{
temp=asc3216[z]; //µ÷ÓÃ3216×ÖÌå
}
z++;
for(t1=0;t1<8;t1++)
{
if(temp&0x01)LCD_DrawPoint(x,y);
temp>>=1;
x++;
if(x>=lcddev.width){POINT_COLOR=colortemp;return;}//³¬ÇøÓòÁË
if((x-x0)==(size/2))
{
x=x0;
y++;
if(y>=lcddev.height){POINT_COLOR=colortemp;return;}//³¬ÇøÓòÁË
break;
}
}
}
}
POINT_COLOR=colortemp;
}
//»µã
//x,y:×ø±ê
//POINT_COLOR:´ËµãµÄÑÕÉ«
void LCD_DrawPoint(u16 x,u16 y)
{
LCD_SetCursor(x,y); //ÉèÖùâ±êλÖÃ
LCD->LCD_REG = lcddev.wramcmd;
// LCD_WriteRAM_Prepare(); //¿ªÊ¼Ð´ÈëGRAM
LCD->LCD_RAM = POINT_COLOR;
}
void LCD_SetCursor(u16 Xpos, u16 Ypos)
{
LCD->LCD_REG = 0x002A;
// LCD->LCD_RAM = Xpos;
LCD->LCD_RAM = Xpos>>8; //д¸ß°Ëλ
LCD->LCD_RAM = Xpos&0x00ff; //дµÍ°Ëλ
LCD->LCD_RAM = 799>>8; //дÈë×î´óXÖµ
LCD->LCD_RAM = 799&0x00ff;
LCD->LCD_REG = 0x002b;
LCD->LCD_RAM = Ypos>>8;
LCD->LCD_RAM = Ypos&0x00ff;
LCD->LCD_RAM = 479>>8; //дÈë×î´óYÖµ
LCD->LCD_RAM = 479&0x00ff;
}
修改后的驱动函数如下：
void LCD_ShowNumBig(u16 x,u16 y,u8 num)
{
u8 temp,t1;
u16 t = 0;
u16 z=0;
u16 qyt=BIG_H*(BIG_W>>3); //¼ÆËãÿ¸ö×ÖĸռÓõÄ×Ö½ÚÊý
z=num;
z*=qyt;
LCD_FastSetCursor(x,y,x+BIG_W-1,y+BIG_H-1); //ÉèÖÃÏÔʾÇøÓò
LCD->LCD_REG = LCD1963_WRITE_MEM; //Æô¶¯´æ´¢Æ÷дÃüÁî
for(t=0;t<qyt;t++)
{
temp = asc256128[z++];
for(t1=0;t1<8;t1++)
{
LCD->LCD_RAM = temp&0x80? POINT_COLOR : BACK_COLOR;
temp<<=1;
}
}
}
2.去掉字模中的无用信息
字体取模时我们可以看到如下图所示，字母的上下左右包含很多空白区域（无用信息），我们可以通过设置红框内的参数，将上下左右的无用信息裁剪掉，此方法可以提升约40%的速度，降低2/5字模存储容量。
3.降低FSMC的数据建立时间和保持时间
FSMC初始化代码如下，对参数进行设置即可。
void LCD_Init(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
FSMC_NORSRAMInitTypeDef FSMC_NORSRAMInitStructure;
FSMC_NORSRAMTimingInitTypeDef readWriteTiming;
FSMC_NORSRAMTimingInitTypeDef writeTiming;
// Enable FSMC, GPIOD, GPIOE clocks
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_FSMC, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB | RCC_APB2Periph_GPIOD | RCC_APB2Periph_GPIOE,ENABLE);
// Set PD.00(D2), PD.01(D3), PD.04(NOE), PD.05(NWE), PD.07(NE1), PD.08(D13),
// PD.09(D14), PD.10(D15), PD.13(A18), PD.14(D0), PD.15(D1) as alternate
// function push pull
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_4 | GPIO_Pin_5 |
GPIO_Pin_7 | GPIO_Pin_8 | GPIO_Pin_9 | GPIO_Pin_10|
GPIO_Pin_13 | GPIO_Pin_14 | GPIO_Pin_15;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOD, &GPIO_InitStructure);
// Set PE.07(D4), PE.08(D5), PE.09(D6), PE.10(D7), PE.11(D8), PE.12(D9), PE.13(D10),
// PE.14(D11), PE.15(D12) as alternate function push pull */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7 | GPIO_Pin_8 | GPIO_Pin_9 | GPIO_Pin_10 |
GPIO_Pin_11 | GPIO_Pin_12 | GPIO_Pin_13 | GPIO_Pin_14 |
GPIO_Pin_15;
GPIO_Init(GPIOE, &GPIO_InitStructure);
//PB14 --> LCD_RST
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_Init(GPIOB, &GPIO_InitStructure);
readWriteTiming.FSMC_AddressSetupTime = 1; //µØÖ·½¨Á¢Ê±¼ä£¨ADDSET£©Îª2¸öHCLK 1/36M=27ns
readWriteTiming.FSMC_AddressHoldTime = 1; //µØÖ·±£³Öʱ¼ä£¨ADDHLD£©Ä£Ê½AδÓõ½
readWriteTiming.FSMC_DataSetupTime = 1; // Êý¾Ý±£´æʱ¼äΪ16¸öHCLK,ÒòΪҺ¾§Çý¶¯ICµÄ¶ÁÊý¾ÝµÄʱºò£¬ËٶȲ»ÄÜÌ«¿ì£¬ÓÈÆä¶Ô1289Õâ¸öIC¡£
readWriteTiming.FSMC_BusTurnAroundDuration = 1;
readWriteTiming.FSMC_CLKDivision = 1;
readWriteTiming.FSMC_DataLatency = 1;
readWriteTiming.FSMC_AccessMode = FSMC_AccessMode_A; //ģʽA
writeTiming.FSMC_AddressSetupTime = 1; //µØÖ·½¨Á¢Ê±¼ä£¨ADDSET£©Îª1¸öHCLK
writeTiming.FSMC_AddressHoldTime = 1; //µØÖ·±£³Öʱ¼ä£¨A
writeTiming.FSMC_DataSetupTime = 1; ////Êý¾Ý±£´æʱ¼äΪ4¸öHCLK
writeTiming.FSMC_BusTurnAroundDuration =1;
writeTiming.FSMC_CLKDivision =1;
writeTiming.FSMC_DataLatency =1;
writeTiming.FSMC_AccessMode = FSMC_AccessMode_A; //ģʽA
FSMC_NORSRAMInitStructure.FSMC_Bank = FSMC_Bank1_NORSRAM1;// ÕâÀïÎÒÃÇʹÓÃNE4 £¬Ò²¾Í¶ÔÓ¦BTCR[6],[7]¡£
FSMC_NORSRAMInitStructure.FSMC_DataAddressMux = FSMC_DataAddressMux_Disable; // ²»¸´ÓÃÊý¾ÝµØÖ·
FSMC_NORSRAMInitStructure.FSMC_MemoryType =FSMC_MemoryType_SRAM;// FSMC_MemoryType_SRAM; //SRAM
FSMC_NORSRAMInitStructure.FSMC_MemoryDataWidth = FSMC_MemoryDataWidth_16b;//´æ´¢Æ÷Êý¾Ý¿í¶ÈΪ16bit
FSMC_NORSRAMInitStructure.FSMC_BurstAccessMode =FSMC_BurstAccessMode_Disable;// FSMC_BurstAccessMode_Disable;
FSMC_NORSRAMInitStructure.FSMC_WaitSignalPolarity = FSMC_WaitSignalPolarity_Low;
FSMC_NORSRAMInitStructure.FSMC_AsynchronousWait=FSMC_AsynchronousWait_Disable;
FSMC_NORSRAMInitStructure.FSMC_WrapMode = FSMC_WrapMode_Disable;
FSMC_NORSRAMInitStructure.FSMC_WaitSignalActive = FSMC_WaitSignalActive_BeforeWaitState;
FSMC_NORSRAMInitStructure.FSMC_WriteOperation = FSMC_WriteOperation_Enable; // ´æ´¢Æ÷дʹÄÜ
FSMC_NORSRAMInitStructure.FSMC_WaitSignal = FSMC_WaitSignal_Disable;
FSMC_NORSRAMInitStructure.FSMC_ExtendedMode = FSMC_ExtendedMode_Enable; // ¶ÁдʹÓò»Í¬µÄʱÐò
FSMC_NORSRAMInitStructure.FSMC_WriteBurst = FSMC_WriteBurst_Disable;
FSMC_NORSRAMInitStructure.FSMC_ReadWriteTimingStruct = &readWriteTiming; //¶ÁдʱÐò
FSMC_NORSRAMInitStructure.FSMC_WriteTimingStruct = &writeTiming; //дʱÐò
FSMC_NORSRAMInit(&FSMC_NORSRAMInitStructure); //³õʼ»¯FSMCÅäÖÃ
FSMC_NORSRAMCmd(FSMC_Bank1_NORSRAM1, ENABLE); // ʹÄÜBANK1
}
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