STM32直接驅動ov7670 開發筆記
加入技術交流群
經過我的調試發現，要成功的關鍵：首先是時鐘的初始化，直接驅動時時鐘設置和寄存器設定常理不一樣（這有可能是因為直接驅動太慢的緣故）下面代碼我會詳細說明；第二個是圖像數據的讀取很容易丟失掉第一個字節，（這是很多花屏的原因，很重要很重）最后就會出現反色呀，有規律的花屏呀，圖像不正常等等（有fifo的肯定就不會有這些情況）；第三是增益控制，因為直接驅動速度是相當慢的所以得把增益關掉，如果圖像全是白的，或者很紅有可能就是這原因。第四就是圖像窗口和圖像格式的設置，下面我把寄存器配置貼出來，注意下面的代碼只適合直接驅動方式（時鐘由STM32產生）。
/**********很重要內部時鐘分頻如果是直接驅動必須為0x80(不知道為何 直接使用外部時鐘顏色不對ox40時)原因是數據起始讀取不對 （0x40是容易把第一個數據丟掉，要特別注意）****/
{0x11,(0x040|0x00)},
/********0x3a 和 0x3d *************/
/***0x3d com13 [1] 0x3a TSLB [3]
* 1 1 VYUY
********************************************/
{0x3a,0x04},//yuv輸出順序
{0x3d,0xc2},//110000010 位[6]：UV飽和度標準-UV自動調整
/********0X12 AND 0X40*************
*這兩個決定了輸出圖像的格式
**********************************/
{0x12,0x14},//輸出圖片模式為QVGA RGB
{0X40,0xd0},//輸出數據范圍 rgb565使能
{0x1e,0x17},//水平鏡像/豎直翻轉使能 //0x17為正面 37是鏡面
/****0x17 18 32 0x19 1a 0a *******
*開窗口的大小設置
***********************************/
{0x17,0x16},//hstart
{0x18,0x04},//hstop
{0x32,0x80},//href
{0x19,0x02},
{0x1a,0x7b},//0x7a
{0x03,0x0a},//幀豎直方向控制 0x0a
/**********************************/
{0x0c,0x00},//
{0x3e,0x00},//pclk分頻
/***********
*圖像和測試開關
************************/
{0x70,0x3a},//測試圖案
{0x71,0x35},//測試圖案 35
{0x72,0x11},//dcw控制 設置亞抽樣率 320*240
{0x73,0xf0},//dsp縮放時鐘f0 f0
{0x55,0x00},//亮度控制 0x00最亮 00
{0x56,0x80},//對比度控制 80
{0xa2,0x02},//像素始終延遲
{0x7a,0x20},//伽馬校正
{0x7b,0x10},
{0x7c,0x1e},
{0x7d,0x35},
{0x7e,0x5a},
{0x7f,0x69},
{0x80,0x76},
{0x81,0x80},
{0x82,0x88},
{0x83,0x8f},
{0x84,0x96},
{0x85,0xa3},
{0x86,0xaf},
{0x87,0xc4},
{0x88,0xd7},
{0x89,0xe8},
{0x13,0xef},//agc/aec/awb使能 條紋濾波
/*********增益控制********
*慢速是要關掉
*******************************/
{0x00,0x00},//自動增益控制 ff
/****曝光值 該寄存器提供[9:2] 07 AEGHH[15:10] 04COM1[1:0]******/
{0x07,0x00},
{0x10,0x00},
{0x04,0x00},
{0x0d,0x00},//different 0x60 10
{0x42,0x40},//aec窗口 0x80
{0x14,0x18},//自動增益限度 固定aec/agc
{0xa5,0x08},//50Hz條紋濾波器步長限制 0x08
{0xab,0x08},//60Hz條紋濾波器步長限制 0x08
{0x24,0x75},//AGC/AEC-穩定運行區域（上限）
{0x25,0x63},//AGC/AEC-穩定運行區域（下限）
{0x26,0xd4},//AGC/AEC快速運行區域
{0x9f,0x78},
{0xa0,0x68},
{0xa1,0x03},
{0xa6,0xd8},
{0xa7,0xd8},
{0xa8,0xf0},
{0xa9,0x90},
{0xaa,0x14},
{0x13,0xe5},//打開agc aec
{0x0e,0x61},
{0x0f,0x4b},
{0x16,0x02},
{0x21,0x02},
{0x22,0x91},
{0x29,0x07},
{0x33,0x0b},
{0x35,0x0b},
{0x37,0x1d},
{0x38,0x71},
{0x39,0x2a},
{0x3c,0x78},
{0x4d,0x40},
{0x4e,0x20},
{0x69,0x00},//固定增益控制
/*****這個很重要 直接驅動時不能設為0x00***/
{0x6b,0x0a},//pll 內部ld0
{0x74,0x10},
{0x8d,0x4f},
{0x8e,0x00},
{0x8f,0x00},
{0x90,0x00},
{0x91,0x00},
{0x92,0x19},
{0x96,0x00},
{0x9a,0x80},
{0xb0,0x84},
{0xb1,0x0c},
{0xb2,0x0e},
{0xb3,0x82},
{0xb8,0x0a},
{0x43,0x0a},
{0x44,0xf0},
{0x45,0x34},
{0x46,0x58},
{0x47,0x28},
{0x48,0x3a},
{0x59,0x88},
{0x5a,0x88},
{0x5b,0x44},
{0x5c,0x67},
{0x5d,0x49},
{0x5e,0x0e},
{0x64,0x04},
{0x65,0x20},
{0x66,0x05},
{0x94,0x04},
{0x95,0x08},
{0x6c,0x0a},
{0x6d,0x55},
{0x6e,0x11},
{0x6f,0x9f},//0x9e for advanced AWB
{0x6a,0x40},
{0x01,0x40},
{0x02,0x40},
{0x13,0xe7},
{0x4f,0x86},//80/86/8c/93/99
{0x50,0x86},//80/86/8c/93/99
{0x51,0x00},//00/00/00/00/00
{0x52,0x23},//22/23/25/27/28
{0x53,0x62},//5e/62/67/6c/70
{0x54,0x86},//80/86/8c/93/99
{0x58,0x9e},
{0x41,0x08},
{0x3f,0x1f},//邊緣增強調整 位[4：0]：邊緣增強系數
{0x75,0x10},//位[4：0]：邊緣增強下限 0x0f
{0x76,0xc0},//位[4：0]：邊緣增強上限 0x01
{0x4c,0xff},//噪聲抑制強度
{0x77,0x01},
{0x3d,0xc2},//110000010 位[6]：UV飽和度標準-UV自動調整
{0x4b,0x09},
{0xc9,0xf0},//飽和度控制
{0x41,0x3a},//針對YUV邊緣增強閾值自動調整 AWB增益使能
{0x34,0x11},
{0x3b,0x0a},
{0xa4,0x88},
{0x96,0x00},
{0x97,0x30},
{0x98,0x20},
{0x99,0x30},
{0x9a,0x84},
{0x9b,0x29},
{0x9c,0x03},
{0x9d,0x4b},
{0x9e,0x3f},
{0x78,0x04},
{0x79,0x01},
{0xc8,0xf0},
{0x79,0x0f},
{0xc8,0x00},
{0x79,0x10},
{0xc8,0x7e},
{0x79,0x0a},
{0xc8,0x80},
{0x79,0x0b},
{0xc8,0x01},
{0x79,0x0c},
{0xc8,0x0f},
{0x79,0x0d},
{0xc8,0x20},
{0x79,0x09},
{0xc8,0x80},
{0x79,0x02},
{0xc8,0xc0},
{0x79,0x03},
{0xc8,0x40},
{0x79,0x05},
{0xc8,0x30},
{0x79,0x26},
{0x2d,0x00},
{0x2e,0x00},
這個配置表一般就可以出圖像了，或許你還出不來的話就得看看你用的STM32是不是fsmc接口驅動的lcd，如果不是那就99%不行了。有了配置表我在把主函數貼出來，大家可以改進算法，最近也沒時間再改進了（因為我最終的任務是驅動CCD所以cmos只是一個過場）；想要提高水品還得靠自己。
主程序（關鍵代碼）：
void main(void)
{
uint32_t PCnt=0;
static uint8_t Cnt= 0;
u16 value=0,val1=0,val2=0,REG=0;
/**************************/
SysTick_Init();
TIME2_Init( );
START_TIME;
Init_CCD_OV7670( );
LCD_Init();
Delay_us(20);
LCD_REG=R34;
CCD_EXTI_Init( );
while(1)
{
PCnt = 0;
Cnt = 1;
XClock_Init( ); //OV7670 XCLK 開 （我用的是TIM2產生PWM波，開關只要改變相應引腳狀態就好了）
while(value & 0x0004) value = GPIOE->IDR; // Vsync=H
while(~value & 0x0004) value = GPIOE->IDR; // Vsync=L
XClock_OUT(); //OV7670 XCLK 關
/*******直接使用時鐘時要加一個低電平*************
*不然會把第一個字節丟掉，產生反色或者是花紋的現象
*正常數據 (R G B) (R G B) (R G B )
*丟失第一字節 (G B R) (G B R) (G B
************************************************/
XCLK_L;
while(PCnt<76800)
{
XCLK_H;
XCLK_L;
REG = GPIOE->IDR;
if(REG&0x0002) // HREF = H 水平信號高時有數據
{
if(REG&0x0001){ //PCLK = H 再次判斷像素時鐘是不是高
value = GPIOC->IDR;
if((Cnt == 1))// 高字節
{
val1=(value<<8);
Cnt=0;
}
else // 低字節
{
val2=(value&0x00ff);
Cnt = 1;
LCD_RAM =val1 |val2; //(我用的是fsmc接口所以才可以這樣寫)
PCnt ++;
}
}
}
}
}
}
//快的時鐘一定要用定時器的PWM功能，定時器中斷翻轉電平是無法實現的，切記。
好了就寫這么多，應該對大家有幫助。
評論