user29660: I have read a great deal today about interfacing the OV7670 with the Arduino Uno. I decided to jump in and start tinkering with this thing. I wired it up according to this schematic:

And I copied and pasted the sketch I found here (http://www.instructables.com/id/OV7670-Without-FIFO-Very-Simple-Framecapture-With-/step3/Upload-sketch-to-Arduino/):
// Source code for application to transmit image from ov7670 to PC via USB
// By Siarhei Charkes in 2015
// http://privateblog.info 
//

#include <stdint.h>
#include <avr/io.h>
#include <util/twi.h>
#include <util/delay.h>
#include <avr/pgmspace.h>

#define F_CPU 16000000UL
#define vga   0
#define qvga  1
#define qqvga   2
#define yuv422  0
#define rgb565  1
#define bayerRGB  2
#define camAddr_WR  0x42
#define camAddr_RD  0x43

/* Registers */
#define REG_GAIN    0x00  /* Gain lower 8 bits (rest in vref) */
#define REG_BLUE    0x01  /* blue gain */
#define REG_RED       0x02  /* red gain */
#define REG_VREF    0x03  /* Pieces of GAIN, VSTART, VSTOP */
#define REG_COM1    0x04  /* Control 1 */
#define COM1_CCIR656  0x40    /* CCIR656 enable */

#define REG_BAVE    0x05  /* U/B Average level */
#define REG_GbAVE   0x06  /* Y/Gb Average level */
#define REG_AECHH   0x07  /* AEC MS 5 bits */
#define REG_RAVE    0x08  /* V/R Average level */
#define REG_COM2    0x09  /* Control 2 */
#define COM2_SSLEEP         0x10  /* Soft sleep mode */
#define REG_PID           0x0a  /* Product ID MSB */
#define REG_VER           0x0b  /* Product ID LSB */
#define REG_COM3    0x0c  /* Control 3 */
#define COM3_SWAP         0x40  /* Byte swap */
#define COM3_SCALEEN          0x08  /* Enable scaling */
#define COM3_DCWEN          0x04  /* Enable downsamp/crop/window */
#define REG_COM4    0x0d  /* Control 4 */
#define REG_COM5    0x0e  /* All "reserved" */
#define REG_COM6    0x0f  /* Control 6 */
#define REG_AECH    0x10  /* More bits of AEC value */
#define REG_CLKRC   0x11  /* Clocl control */
#define CLK_EXT           0x40  /* Use external clock directly */
#define CLK_SCALE   0x3f  /* Mask for internal clock scale */
#define REG_COM7    0x12  /* Control 7 */ //REG mean address.
#define COM7_RESET          0x80  /* Register reset */
#define COM7_FMT_MASK         0x38
#define COM7_FMT_VGA          0x00
#define COM7_FMT_CIF          0x20  /* CIF format */
#define COM7_FMT_QVGA         0x10  /* QVGA format */
#define COM7_FMT_QCIF         0x08  /* QCIF format */
#define COM7_RGB          0x04  /* bits 0 and 2 - RGB format */
#define COM7_YUV          0x00  /* YUV */
#define COM7_BAYER          0x01  /* Bayer format */
#define COM7_PBAYER         0x05  /* "Processed bayer" */
#define REG_COM8    0x13  /* Control 8 */
#define COM8_FASTAEC          0x80  /* Enable fast AGC/AEC */
#define COM8_AECSTEP          0x40  /* Unlimited AEC step size */
#define COM8_BFILT    0x20  /* Band filter enable */
#define COM8_AGC    0x04  /* Auto gain enable */
#define COM8_AWB    0x02  /* White balance enable */
#define COM8_AEC    0x01  /* Auto exposure enable */
#define REG_COM9    0x14  /* Control 9- gain ceiling */
#define REG_COM10   0x15  /* Control 10 */
#define COM10_HSYNC         0x40  /* HSYNC instead of HREF */
#define COM10_PCLK_HB         0x20  /* Suppress PCLK on horiz blank */
#define COM10_HREF_REV          0x08  /* Reverse HREF */
#define COM10_VS_LEAD         0x04  /* VSYNC on clock leading edge */
#define COM10_VS_NEG          0x02  /* VSYNC negative */
#define COM10_HS_NEG          0x01  /* HSYNC negative */
#define REG_HSTART    0x17  /* Horiz start high bits */
#define REG_HSTOP   0x18  /* Horiz stop high bits */
#define REG_VSTART    0x19  /* Vert start high bits */
#define REG_VSTOP   0x1a  /* Vert stop high bits */
#define REG_PSHFT   0x1b  /* Pixel delay after HREF */
#define REG_MIDH    0x1c  /* Manuf. ID high */
#define REG_MIDL    0x1d  /* Manuf. ID low */
#define REG_MVFP    0x1e  /* Mirror / vflip */
#define MVFP_MIRROR         0x20  /* Mirror image */
#define MVFP_FLIP   0x10  /* Vertical flip */

#define REG_AEW           0x24  /* AGC upper limit */
#define REG_AEB           0x25    /* AGC lower limit */
#define REG_VPT           0x26  /* AGC/AEC fast mode op region */
#define REG_HSYST   0x30  /* HSYNC rising edge delay */
#define REG_HSYEN   0x31  /* HSYNC falling edge delay */
#define REG_HREF    0x32  /* HREF pieces */
#define REG_TSLB    0x3a  /* lots of stuff */
#define TSLB_YLAST    0x04  /* UYVY or VYUY - see com13 */
#define REG_COM11   0x3b  /* Control 11 */
#define COM11_NIGHT         0x80  /* NIght mode enable */
#define COM11_NMFR          0x60  /* Two bit NM frame rate */
#define COM11_HZAUTO          0x10  /* Auto detect 50/60 Hz */
#define COM11_50HZ          0x08  /* Manual 50Hz select */
#define COM11_EXP   0x02
#define REG_COM12   0x3c  /* Control 12 */
#define COM12_HREF          0x80  /* HREF always */
#define REG_COM13   0x3d  /* Control 13 */
#define COM13_GAMMA         0x80  /* Gamma enable */
#define COM13_UVSAT         0x40  /* UV saturation auto adjustment */
#define COM13_UVSWAP          0x01  /* V before U - w/TSLB */
#define REG_COM14   0x3e  /* Control 14 */
#define COM14_DCWEN         0x10  /* DCW/PCLK-scale enable */
#define REG_EDGE    0x3f  /* Edge enhancement factor */
#define REG_COM15   0x40  /* Control 15 */
#define COM15_R10F0         0x00  /* Data range 10 to F0 */
#define COM15_R01FE         0x80  /*      01 to FE */
#define COM15_R00FF         0xc0  /*      00 to FF */
#define COM15_RGB565          0x10  /* RGB565 output */
#define COM15_RGB555          0x30  /* RGB555 output */
#define REG_COM16   0x41  /* Control 16 */
#define COM16_AWBGAIN         0x08  /* AWB gain enable */
#define REG_COM17   0x42  /* Control 17 */
#define COM17_AECWIN          0xc0  /* AEC window - must match COM4 */
#define COM17_CBAR          0x08  /* DSP Color bar */
/*
* This matrix defines how the colors are generated, must be
* tweaked to adjust hue and saturation.
*
* Order: v-red, v-green, v-blue, u-red, u-green, u-blue
* They are nine-bit signed quantities, with the sign bit
* stored in0x58.Sign for v-red is bit 0, and up from there.
*/
#define REG_CMATRIX_BASE  0x4f
#define CMATRIX_LEN           6
#define REG_CMATRIX_SIGN  0x58
#define REG_BRIGHT    0x55  /* Brightness */
#define REG_CONTRAS         0x56  /* Contrast control */
#define REG_GFIX    0x69  /* Fix gain control */
#define REG_REG76   0x76  /* OV's name */
#define R76_BLKPCOR         0x80  /* Black pixel correction enable */
#define R76_WHTPCOR         0x40  /* White pixel correction enable */
#define REG_RGB444          0x8c  /* RGB 444 control */
#define R444_ENABLE         0x02  /* Turn on RGB444, overrides 5x5 */
#define R444_RGBX   0x01  /* Empty nibble at end */
#define REG_HAECC1    0x9f  /* Hist AEC/AGC control 1 */
#define REG_HAECC2    0xa0  /* Hist AEC/AGC control 2 */
#define REG_BD50MAX         0xa5  /* 50hz banding step limit */
#define REG_HAECC3    0xa6  /* Hist AEC/AGC control 3 */
#define REG_HAECC4    0xa7  /* Hist AEC/AGC control 4 */
#define REG_HAECC5    0xa8  /* Hist AEC/AGC control 5 */
#define REG_HAECC6    0xa9  /* Hist AEC/AGC control 6 */
#define REG_HAECC7    0xaa  /* Hist AEC/AGC control 7 */
#define REG_BD60MAX         0xab  /* 60hz banding step limit */
#define REG_GAIN    0x00  /* Gain lower 8 bits (rest in vref) */
#define REG_BLUE    0x01  /* blue gain */
#define REG_RED           0x02  /* red gain */
#define REG_VREF    0x03  /* Pieces of GAIN, VSTART, VSTOP */
#define REG_COM1    0x04  /* Control 1 */
#define COM1_CCIR656          0x40  /* CCIR656 enable */
#define REG_BAVE    0x05  /* U/B Average level */
#define REG_GbAVE   0x06  /* Y/Gb Average level */
#define REG_AECHH   0x07  /* AEC MS 5 bits */
#define REG_RAVE    0x08  /* V/R Average level */
#define REG_COM2    0x09  /* Control 2 */
#define COM2_SSLEEP         0x10  /* Soft sleep mode */
#define REG_PID           0x0a  /* Product ID MSB */
#define REG_VER           0x0b  /* Product ID LSB */
#define REG_COM3    0x0c  /* Control 3 */
#define COM3_SWAP         0x40  /* Byte swap */
#define COM3_SCALEEN          0x08  /* Enable scaling */
#define COM3_DCWEN          0x04  /* Enable downsamp/crop/window */
#define REG_COM4    0x0d  /* Control 4 */
#define REG_COM5    0x0e  /* All "reserved" */
#define REG_COM6    0x0f  /* Control 6 */
#define REG_AECH    0x10  /* More bits of AEC value */
#define REG_CLKRC   0x11  /* Clocl control */
#define CLK_EXT           0x40  /* Use external clock directly */
#define CLK_SCALE   0x3f  /* Mask for internal clock scale */
#define REG_COM7    0x12  /* Control 7 */
#define COM7_RESET          0x80  /* Register reset */
#define COM7_FMT_MASK         0x38
#define COM7_FMT_VGA          0x00
#define COM7_FMT_CIF          0x20  /* CIF format */
#define COM7_FMT_QVGA         0x10  /* QVGA format */
#define COM7_FMT_QCIF         0x08  /* QCIF format */
#define COM7_RGB    0x04  /* bits 0 and 2 - RGB format */
#define COM7_YUV    0x00  /* YUV */
#define COM7_BAYER          0x01  /* Bayer format */
#define COM7_PBAYER         0x05  /* "Processed bayer" */
#define REG_COM8    0x13  /* Control 8 */
#define COM8_FASTAEC          0x80  /* Enable fast AGC/AEC */
#define COM8_AECSTEP          0x40  /* Unlimited AEC step size */
#define COM8_BFILT    0x20  /* Band filter enable */
#define COM8_AGC    0x04  /* Auto gain enable */
#define COM8_AWB    0x02  /* White balance enable */
#define COM8_AEC    0x01  /* Auto exposure enable */
#define REG_COM9    0x14  /* Control 9- gain ceiling */
#define REG_COM10   0x15  /* Control 10 */
#define COM10_HSYNC         0x40  /* HSYNC instead of HREF */
#define COM10_PCLK_HB         0x20  /* Suppress PCLK on horiz blank */
#define COM10_HREF_REV          0x08  /* Reverse HREF */
#define COM10_VS_LEAD           0x04  /* VSYNC on clock leading edge */
#define COM10_VS_NEG          0x02  /* VSYNC negative */
#define COM10_HS_NEG          0x01  /* HSYNC negative */
#define REG_HSTART    0x17  /* Horiz start high bits */
#define REG_HSTOP   0x18  /* Horiz stop high bits */
#define REG_VSTART    0x19  /* Vert start high bits */
#define REG_VSTOP   0x1a  /* Vert stop high bits */
#define REG_PSHFT   0x1b  /* Pixel delay after HREF */
#define REG_MIDH    0x1c  /* Manuf. ID high */
#define REG_MIDL    0x1d  /* Manuf. ID low */
#define REG_MVFP    0x1e  /* Mirror / vflip */
#define MVFP_MIRROR         0x20  /* Mirror image */
#define MVFP_FLIP   0x10  /* Vertical flip */
#define REG_AEW           0x24  /* AGC upper limit */
#define REG_AEB           0x25  /* AGC lower limit */
#define REG_VPT           0x26  /* AGC/AEC fast mode op region */
#define REG_HSYST   0x30  /* HSYNC rising edge delay */
#define REG_HSYEN   0x31  /* HSYNC falling edge delay */
#define REG_HREF    0x32  /* HREF pieces */
#define REG_TSLB    0x3a  /* lots of stuff */
#define TSLB_YLAST    0x04  /* UYVY or VYUY - see com13 */
#define REG_COM11   0x3b  /* Control 11 */
#define COM11_NIGHT         0x80  /* NIght mode enable */
#define COM11_NMFR          0x60  /* Two bit NM frame rate */
#define COM11_HZAUTO          0x10  /* Auto detect 50/60 Hz */
#define COM11_50HZ          0x08  /* Manual 50Hz select */
#define COM11_EXP   0x02
#define REG_COM12   0x3c  /* Control 12 */
#define COM12_HREF          0x80  /* HREF always */
#define REG_COM13   0x3d  /* Control 13 */
#define COM13_GAMMA         0x80  /* Gamma enable */
#define COM13_UVSAT         0x40  /* UV saturation auto adjustment */
#define COM13_UVSWAP          0x01  /* V before U - w/TSLB */
#define REG_COM14   0x3e  /* Control 14 */
#define COM14_DCWEN         0x10  /* DCW/PCLK-scale enable */
#define REG_EDGE    0x3f  /* Edge enhancement factor */
#define REG_COM15   0x40  /* Control 15 */
#define COM15_R10F0         0x00  /* Data range 10 to F0 */
#define COM15_R01FE         0x80  /*      01 to FE */
#define COM15_R00FF         0xc0  /*      00 to FF */
#define COM15_RGB565          0x10  /* RGB565 output */
#define COM15_RGB555          0x30  /* RGB555 output */
#define REG_COM16   0x41  /* Control 16 */
#define COM16_AWBGAIN         0x08  /* AWB gain enable */
#define REG_COM17   0x42  /* Control 17 */
#define COM17_AECWIN          0xc0  /* AEC window - must match COM4 */
#define COM17_CBAR          0x08  /* DSP Color bar */

#define CMATRIX_LEN             6
#define REG_BRIGHT    0x55  /* Brightness */
#define REG_REG76   0x76  /* OV's name */
#define R76_BLKPCOR         0x80  /* Black pixel correction enable */
#define R76_WHTPCOR         0x40  /* White pixel correction enable */
#define REG_RGB444          0x8c  /* RGB 444 control */
#define R444_ENABLE         0x02  /* Turn on RGB444, overrides 5x5 */
#define R444_RGBX   0x01  /* Empty nibble at end */
#define REG_HAECC1    0x9f  /* Hist AEC/AGC control 1 */
#define REG_HAECC2    0xa0  /* Hist AEC/AGC control 2 */
#define REG_BD50MAX         0xa5  /* 50hz banding step limit */
#define REG_HAECC3    0xa6  /* Hist AEC/AGC control 3 */
#define REG_HAECC4    0xa7  /* Hist AEC/AGC control 4 */
#define REG_HAECC5    0xa8  /* Hist AEC/AGC control 5 */
#define REG_HAECC6    0xa9  /* Hist AEC/AGC control 6 */
#define REG_HAECC7    0xaa  /* Hist AEC/AGC control 7 */
#define REG_BD60MAX         0xab  /* 60hz banding step limit */
#define MTX1            0x4f  /* Matrix Coefficient 1 */
#define MTX2            0x50  /* Matrix Coefficient 2 */
#define MTX3            0x51  /* Matrix Coefficient 3 */
#define MTX4            0x52  /* Matrix Coefficient 4 */
#define MTX5            0x53  /* Matrix Coefficient 5 */
#define MTX6            0x54  /* Matrix Coefficient 6 */
#define REG_CONTRAS         0x56  /* Contrast control */
#define MTXS            0x58  /* Matrix Coefficient Sign */
#define AWBC7           0x59  /* AWB Control 7 */
#define AWBC8           0x5a  /* AWB Control 8 */
#define AWBC9           0x5b  /* AWB Control 9 */
#define AWBC10            0x5c  /* AWB Control 10 */
#define AWBC11            0x5d  /* AWB Control 11 */
#define AWBC12            0x5e  /* AWB Control 12 */
#define REG_GFI           0x69  /* Fix gain control */
#define GGAIN           0x6a  /* G Channel AWB Gain */
#define DBLV            0x6b  
#define AWBCTR3           0x6c  /* AWB Control 3 */
#define AWBCTR2           0x6d  /* AWB Control 2 */
#define AWBCTR1           0x6e  /* AWB Control 1 */
#define AWBCTR0           0x6f  /* AWB Control 0 */

struct regval_list{
  uint8_t reg_num;
  uint16_t value;
};

const struct regval_list qvga_ov7670[] PROGMEM = {
  { REG_COM14, 0x19 },
  { 0x72, 0x11 },
  { 0x73, 0xf1 },

  { REG_HSTART, 0x16 },
  { REG_HSTOP, 0x04 },
  { REG_HREF, 0xa4 },
  { REG_VSTART, 0x02 },
  { REG_VSTOP, 0x7a },
  { REG_VREF, 0x0a },


/*  { REG_HSTART, 0x16 },
  { REG_HSTOP, 0x04 },
  { REG_HREF, 0x24 },
  { REG_VSTART, 0x02 },
  { REG_VSTOP, 0x7a },
  { REG_VREF, 0x0a },*/
  { 0xff, 0xff }, /* END MARKER */
};

const struct regval_list yuv422_ov7670[] PROGMEM = {
  { REG_COM7, 0x0 },  /* Selects YUV mode */
  { REG_RGB444, 0 },  /* No RGB444 please */
  { REG_COM1, 0 },
  { REG_COM15, COM15_R00FF },
  { REG_COM9, 0x6A }, /* 128x gain ceiling; 0x8 is reserved bit */
  { 0x4f, 0x80 },   /* "matrix coefficient 1" */
  { 0x50, 0x80 },   /* "matrix coefficient 2" */
  { 0x51, 0 },    /* vb */
  { 0x52, 0x22 },   /* "matrix coefficient 4" */
  { 0x53, 0x5e },   /* "matrix coefficient 5" */
  { 0x54, 0x80 },   /* "matrix coefficient 6" */
  { REG_COM13, COM13_UVSAT },
  { 0xff, 0xff },   /* END MARKER */
};

const struct regval_list ov7670_default_regs[] PROGMEM = {//from the linux driver
  { REG_COM7, COM7_RESET },
  { REG_TSLB, 0x04 }, /* OV */
  { REG_COM7, 0 },  /* VGA */
  /*
  * Set the hardware window.  These values from OV don't entirely
  * make sense - hstop is less than hstart.  But they work...
  */
  { REG_HSTART, 0x13 }, { REG_HSTOP, 0x01 },
  { REG_HREF, 0xb6 }, { REG_VSTART, 0x02 },
  { REG_VSTOP, 0x7a }, { REG_VREF, 0x0a },

  { REG_COM3, 0 }, { REG_COM14, 0 },
  /* Mystery scaling numbers */
  { 0x70, 0x3a }, { 0x71, 0x35 },
  { 0x72, 0x11 }, { 0x73, 0xf0 },
  { 0xa2,/* 0x02 changed to 1*/1 }, { REG_COM10, 0x0 },
  /* Gamma curve values */
  { 0x7a, 0x20 }, { 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 },
  /* AGC and AEC parameters.  Note we start by disabling those features,
  then turn them only after tweaking the values. */
  { REG_COM8, COM8_FASTAEC | COM8_AECSTEP },
  { REG_GAIN, 0 }, { REG_AECH, 0 },
  { REG_COM4, 0x40 }, /* magic reserved bit */
  { REG_COM9, 0x18 }, /* 4x gain + magic rsvd bit */
  { REG_BD50MAX, 0x05 }, { REG_BD60MAX, 0x07 },
  { REG_AEW, 0x95 }, { REG_AEB, 0x33 },
  { REG_VPT, 0xe3 }, { REG_HAECC1, 0x78 },
  { REG_HAECC2, 0x68 }, { 0xa1, 0x03 }, /* magic */
  { REG_HAECC3, 0xd8 }, { REG_HAECC4, 0xd8 },
  { REG_HAECC5, 0xf0 }, { REG_HAECC6, 0x90 },
  { REG_HAECC7, 0x94 },
  { REG_COM8, COM8_FASTAEC | COM8_AECSTEP | COM8_AGC | COM8_AEC },
  { 0x30, 0 }, { 0x31, 0 },//disable some delays
  /* Almost all of these are magic "reserved" values.  */
  { REG_COM5, 0x61 }, { REG_COM6, 0x4b },
  { 0x16, 0x02 }, { REG_MVFP, 0x07 },
  { 0x21, 0x02 }, { 0x22, 0x91 },
  { 0x29, 0x07 }, { 0x33, 0x0b },
  { 0x35, 0x0b }, { 0x37, 0x1d },
  { 0x38, 0x71 }, { 0x39, 0x2a },
  { REG_COM12, 0x78 }, { 0x4d, 0x40 },
  { 0x4e, 0x20 }, { REG_GFIX, 0 },
  /*{0x6b, 0x4a},*/{ 0x74, 0x10 },
  { 0x8d, 0x4f }, { 0x8e, 0 },
  { 0x8f, 0 }, { 0x90, 0 },
  { 0x91, 0 }, { 0x96, 0 },
  { 0x9a, 0 }, { 0xb0, 0x84 },
  { 0xb1, 0x0c }, { 0xb2, 0x0e },
  { 0xb3, 0x82 }, { 0xb8, 0x0a },

  /* More reserved magic, some of which tweaks white balance */
  { 0x43, 0x0a }, { 0x44, 0xf0 },
  { 0x45, 0x34 }, { 0x46, 0x58 },
  { 0x47, 0x28 }, { 0x48, 0x3a },
  { 0x59, 0x88 }, { 0x5a, 0x88 },
  { 0x5b, 0x44 }, { 0x5c, 0x67 },
  { 0x5d, 0x49 }, { 0x5e, 0x0e },
  { 0x6c, 0x0a }, { 0x6d, 0x55 },
  { 0x6e, 0x11 }, { 0x6f, 0x9e }, /* it was 0x9F "9e for advance AWB" */
  { 0x6a, 0x40 }, { REG_BLUE, 0x40 },
  { REG_RED, 0x60 },
  { REG_COM8, COM8_FASTAEC | COM8_AECSTEP | COM8_AGC | COM8_AEC | COM8_AWB },

  /* Matrix coefficients */
  { 0x4f, 0x80 }, { 0x50, 0x80 },
  { 0x51, 0 },    { 0x52, 0x22 },
  { 0x53, 0x5e }, { 0x54, 0x80 },
  { 0x58, 0x9e },

  { REG_COM16, COM16_AWBGAIN }, { REG_EDGE, 0 },
  { 0x75, 0x05 }, { REG_REG76, 0xe1 },
  { 0x4c, 0 },     { 0x77, 0x01 },
  { REG_COM13, /*0xc3*/0x48 }, { 0x4b, 0x09 },
  { 0xc9, 0x60 },   /*{REG_COM16, 0x38},*/
  { 0x56, 0x40 },

  { 0x34, 0x11 }, { REG_COM11, COM11_EXP | COM11_HZAUTO },
  { 0xa4, 0x82/*Was 0x88*/ }, { 0x96, 0 },
  { 0x97, 0x30 }, { 0x98, 0x20 },
  { 0x99, 0x30 }, { 0x9a, 0x84 },
  { 0x9b, 0x29 }, { 0x9c, 0x03 },
  { 0x9d, 0x4c }, { 0x9e, 0x3f },
  { 0x78, 0x04 },

  /* Extra-weird stuff.  Some sort of multiplexor register */
  { 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 },
  { 0xff, 0xff }, /* END MARKER */
};


void error_led(void){
  DDRB |= 32;//make sure led is output
  while (1){//wait for reset
    PORTB ^= 32;// toggle led
    _delay_ms(100);
  }
}

void twiStart(void){
  TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN);//send start
  while (!(TWCR & (1 << TWINT)));//wait for start to be transmitted
  if ((TWSR & 0xF8) != TW_START)
    error_led();
}

void twiWriteByte(uint8_t DATA, uint8_t type){
  TWDR = DATA;
  TWCR = _BV(TWINT) | _BV(TWEN);
  while (!(TWCR & (1 << TWINT))) {}
  if ((TWSR & 0xF8) != type)
    error_led();
}

void twiAddr(uint8_t addr, uint8_t typeTWI){
  TWDR = addr;//send address
  TWCR = _BV(TWINT) | _BV(TWEN);    /* clear interrupt to start transmission */
  while ((TWCR & _BV(TWINT)) == 0); /* wait for transmission */
  if ((TWSR & 0xF8) != typeTWI)
    error_led();
}

void wrReg(uint8_t reg, uint8_t dat){
  //send start condition
  twiStart();
  twiAddr(camAddr_WR, TW_MT_SLA_ACK);
  twiWriteByte(reg, TW_MT_DATA_ACK);
  twiWriteByte(dat, TW_MT_DATA_ACK);
  TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);//send stop
  _delay_ms(1);
}

static uint8_t twiRd(uint8_t nack){
  if (nack){
    TWCR = _BV(TWINT) | _BV(TWEN);
    while ((TWCR & _BV(TWINT)) == 0); /* wait for transmission */
    if ((TWSR & 0xF8) != TW_MR_DATA_NACK)
      error_led();
    return TWDR;
  }
  else{
    TWCR = _BV(TWINT) | _BV(TWEN) | _BV(TWEA);
    while ((TWCR & _BV(TWINT)) == 0); /* wait for transmission */
    if ((TWSR & 0xF8) != TW_MR_DATA_ACK)
      error_led();
    return TWDR;
  }
}

uint8_t rdReg(uint8_t reg){
  uint8_t dat;
  twiStart();
  twiAddr(camAddr_WR, TW_MT_SLA_ACK);
  twiWriteByte(reg, TW_MT_DATA_ACK);
  TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);//send stop
  _delay_ms(1);
  twiStart();
  twiAddr(camAddr_RD, TW_MR_SLA_ACK);
  dat = twiRd(1);
  TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);//send stop
  _delay_ms(1);
  return dat;
}

void wrSensorRegs8_8(const struct regval_list reglist[]){
  uint8_t reg_addr, reg_val;
  const struct regval_list *next = reglist;
  while ((reg_addr != 0xff) | (reg_val != 0xff)){
    reg_addr = pgm_read_byte(&next->reg_num);
    reg_val = pgm_read_byte(&next->value);
    wrReg(reg_addr, reg_val);
    next++;
  }
}

void setColor(void){
  wrSensorRegs8_8(yuv422_ov7670);
}

void setRes(void){
  wrReg(REG_COM3, 4); // REG_COM3 enable scaling
  wrSensorRegs8_8(qvga_ov7670);
}

void camInit(void){
  wrReg(0x12, 0x80);
  _delay_ms(100);
  wrSensorRegs8_8(ov7670_default_regs);
  wrReg(REG_COM10, 32);//PCLK does not toggle on HBLANK.
}

void arduinoUnoInut(void) {
  cli();//disable interrupts

    /* Setup the 8mhz PWM clock
  * This will be on pin 11*/
  DDRB |= (1 << 3);//pin 11
  ASSR &= ~(_BV(EXCLK) | _BV(AS2));
  TCCR2A = (1 << COM2A0) | (1 << WGM21) | (1 << WGM20);
  TCCR2B = (1 << WGM22) | (1 << CS20);
  OCR2A = 0;//(F_CPU)/(2*(X+1))
  DDRC &= ~15;//low d0-d3 camera
  DDRD &= ~252;//d7-d4 and interrupt pins
  _delay_ms(3000);

    //set up twi for 100khz
  TWSR &= ~3;//disable prescaler for TWI
  TWBR = 72;//set to 100khz

    //enable serial
  UBRR0H = 0;
  UBRR0L = 1;//0 = 2M baud rate. 1 = 1M baud. 3 = 0.5M. 7 = 250k 207 is 9600 baud rate.
  UCSR0A |= 2;//double speed aysnc
  UCSR0B = (1 << RXEN0) | (1 << TXEN0);//Enable receiver and transmitter
  UCSR0C = 6;//async 1 stop bit 8bit char no parity bits
}


void StringPgm(const char * str){
  do{
      while (!(UCSR0A & (1 << UDRE0)));//wait for byte to transmit
      UDR0 = pgm_read_byte_near(str);
      while (!(UCSR0A & (1 << UDRE0)));//wait for byte to transmit
  } while (pgm_read_byte_near(++str));
}

static void captureImg(uint16_t wg, uint16_t hg){
  uint16_t y, x;

  StringPgm(PSTR("*RDY*"));

  while (!(PIND & 8));//wait for high
  while ((PIND & 8));//wait for low

    y = hg;
  while (y--){
        x = wg;
      //while (!(PIND & 256));//wait for high
    while (x--){
      while ((PIND & 4));//wait for low
            UDR0 = (PINC & 15) | (PIND & 240);
          while (!(UCSR0A & (1 << UDRE0)));//wait for byte to transmit
      while (!(PIND & 4));//wait for high
      while ((PIND & 4));//wait for low
      while (!(PIND & 4));//wait for high
    }
    //  while ((PIND & 256));//wait for low
  }
    _delay_ms(100);
}

void setup(){
  arduinoUnoInut();
  camInit();
  setRes();
  setColor();
  wrReg(0x11, 11); //Earlier it had the value: wrReg(0x11, 12); New version works better for me :) !!!!
}


void loop(){
  captureImg(320, 240);
}

The sketch has way too many #defines, and isn't exactly straightforward, but at least it loads, although there is one warning:
/Users/charles/Documents/Arduino/cameraTest2/cameraTest2.ino:13:0: warning: "F_CPU" redefined
 #define F_CPU 16000000UL
 ^
<command-line>:0:0: note: this is the location of the previous definition

To validate that this does anything, I tried playing around with ComputerNerd's SimpleFrameGrabber, but I'm on a mac and I ran into problems when trying to ./build:
main.c:26:10: fatal error: 'SDL/SDL.h' file not found
#include <SDL/SDL.h>

I then tried opening up the Arduino IDE Serial Monitor, and am not seeing anything. Should I be seeing anything? I was expecting I would at least see gibberish..
Ideally, I would like to find some simple example code that would setup the camera (the defaults might even be just fine), and allow me to get RGB pixel data for a 320x240 or 640x480 image. If I could just print that to the Serial Output, I could then write a simple python script to save it as a jpg or a png or something. 
I just need to get to a sanity state with this thing. Or find another inexpensive camera module that's easier to work with.

user4628: //enable serial
UBRR0H = 0;
UBRR0L = 1;//0 = 2M baud rate. 1 = 1M baud. 3 = 0.5M. 7 = 250k 207 is 9600 baud rate.
UCSR0A |= 2;//double speed aysnc
UCSR0B = (1 << RXEN0) | (1 << TXEN0);//Enable receiver and transmitter
UCSR0C = 6;//async 1 stop bit 8bit char no parity bits

This bit enables Serial (Rx=0, Tx=1) at 1M baud. Is the Serial Monitor set to the right baud rate?

29660: <p>I have read a great deal today about interfacing the OV7670 with the Arduino Uno. I decided to jump in and start tinkering with this thing. I wired it up according to this schematic:
<a href="https://i.stack.imgur.com/w8xPu.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/w8xPu.png" alt="Wiring Diagram"></a></p>

<p>And I copied and pasted the sketch I found here (<a href="http://www.instructables.com/id/OV7670-Without-FIFO-Very-Simple-Framecapture-With-/step3/Upload-sketch-to-Arduino/" rel="nofollow noreferrer">http://www.instructables.com/id/OV7670-Without-FIFO-Very-Simple-Framecapture-With-/step3/Upload-sketch-to-Arduino/</a>):</p>

<pre><code>// Source code for application to transmit image from ov7670 to PC via USB
// By Siarhei Charkes in 2015
// http://privateblog.info 
//

#include &lt;stdint.h&gt;
#include &lt;avr/io.h&gt;
#include &lt;util/twi.h&gt;
#include &lt;util/delay.h&gt;
#include &lt;avr/pgmspace.h&gt;

#define F_CPU 16000000UL
#define vga   0
#define qvga  1
#define qqvga   2
#define yuv422  0
#define rgb565  1
#define bayerRGB  2
#define camAddr_WR  0x42
#define camAddr_RD  0x43

/* Registers */
#define REG_GAIN    0x00  /* Gain lower 8 bits (rest in vref) */
#define REG_BLUE    0x01  /* blue gain */
#define REG_RED       0x02  /* red gain */
#define REG_VREF    0x03  /* Pieces of GAIN, VSTART, VSTOP */
#define REG_COM1    0x04  /* Control 1 */
#define COM1_CCIR656  0x40    /* CCIR656 enable */

#define REG_BAVE    0x05  /* U/B Average level */
#define REG_GbAVE   0x06  /* Y/Gb Average level */
#define REG_AECHH   0x07  /* AEC MS 5 bits */
#define REG_RAVE    0x08  /* V/R Average level */
#define REG_COM2    0x09  /* Control 2 */
#define COM2_SSLEEP         0x10  /* Soft sleep mode */
#define REG_PID           0x0a  /* Product ID MSB */
#define REG_VER           0x0b  /* Product ID LSB */
#define REG_COM3    0x0c  /* Control 3 */
#define COM3_SWAP         0x40  /* Byte swap */
#define COM3_SCALEEN          0x08  /* Enable scaling */
#define COM3_DCWEN          0x04  /* Enable downsamp/crop/window */
#define REG_COM4    0x0d  /* Control 4 */
#define REG_COM5    0x0e  /* All "reserved" */
#define REG_COM6    0x0f  /* Control 6 */
#define REG_AECH    0x10  /* More bits of AEC value */
#define REG_CLKRC   0x11  /* Clocl control */
#define CLK_EXT           0x40  /* Use external clock directly */
#define CLK_SCALE   0x3f  /* Mask for internal clock scale */
#define REG_COM7    0x12  /* Control 7 */ //REG mean address.
#define COM7_RESET          0x80  /* Register reset */
#define COM7_FMT_MASK         0x38
#define COM7_FMT_VGA          0x00
#define COM7_FMT_CIF          0x20  /* CIF format */
#define COM7_FMT_QVGA         0x10  /* QVGA format */
#define COM7_FMT_QCIF         0x08  /* QCIF format */
#define COM7_RGB          0x04  /* bits 0 and 2 - RGB format */
#define COM7_YUV          0x00  /* YUV */
#define COM7_BAYER          0x01  /* Bayer format */
#define COM7_PBAYER         0x05  /* "Processed bayer" */
#define REG_COM8    0x13  /* Control 8 */
#define COM8_FASTAEC          0x80  /* Enable fast AGC/AEC */
#define COM8_AECSTEP          0x40  /* Unlimited AEC step size */
#define COM8_BFILT    0x20  /* Band filter enable */
#define COM8_AGC    0x04  /* Auto gain enable */
#define COM8_AWB    0x02  /* White balance enable */
#define COM8_AEC    0x01  /* Auto exposure enable */
#define REG_COM9    0x14  /* Control 9- gain ceiling */
#define REG_COM10   0x15  /* Control 10 */
#define COM10_HSYNC         0x40  /* HSYNC instead of HREF */
#define COM10_PCLK_HB         0x20  /* Suppress PCLK on horiz blank */
#define COM10_HREF_REV          0x08  /* Reverse HREF */
#define COM10_VS_LEAD         0x04  /* VSYNC on clock leading edge */
#define COM10_VS_NEG          0x02  /* VSYNC negative */
#define COM10_HS_NEG          0x01  /* HSYNC negative */
#define REG_HSTART    0x17  /* Horiz start high bits */
#define REG_HSTOP   0x18  /* Horiz stop high bits */
#define REG_VSTART    0x19  /* Vert start high bits */
#define REG_VSTOP   0x1a  /* Vert stop high bits */
#define REG_PSHFT   0x1b  /* Pixel delay after HREF */
#define REG_MIDH    0x1c  /* Manuf. ID high */
#define REG_MIDL    0x1d  /* Manuf. ID low */
#define REG_MVFP    0x1e  /* Mirror / vflip */
#define MVFP_MIRROR         0x20  /* Mirror image */
#define MVFP_FLIP   0x10  /* Vertical flip */

#define REG_AEW           0x24  /* AGC upper limit */
#define REG_AEB           0x25    /* AGC lower limit */
#define REG_VPT           0x26  /* AGC/AEC fast mode op region */
#define REG_HSYST   0x30  /* HSYNC rising edge delay */
#define REG_HSYEN   0x31  /* HSYNC falling edge delay */
#define REG_HREF    0x32  /* HREF pieces */
#define REG_TSLB    0x3a  /* lots of stuff */
#define TSLB_YLAST    0x04  /* UYVY or VYUY - see com13 */
#define REG_COM11   0x3b  /* Control 11 */
#define COM11_NIGHT         0x80  /* NIght mode enable */
#define COM11_NMFR          0x60  /* Two bit NM frame rate */
#define COM11_HZAUTO          0x10  /* Auto detect 50/60 Hz */
#define COM11_50HZ          0x08  /* Manual 50Hz select */
#define COM11_EXP   0x02
#define REG_COM12   0x3c  /* Control 12 */
#define COM12_HREF          0x80  /* HREF always */
#define REG_COM13   0x3d  /* Control 13 */
#define COM13_GAMMA         0x80  /* Gamma enable */
#define COM13_UVSAT         0x40  /* UV saturation auto adjustment */
#define COM13_UVSWAP          0x01  /* V before U - w/TSLB */
#define REG_COM14   0x3e  /* Control 14 */
#define COM14_DCWEN         0x10  /* DCW/PCLK-scale enable */
#define REG_EDGE    0x3f  /* Edge enhancement factor */
#define REG_COM15   0x40  /* Control 15 */
#define COM15_R10F0         0x00  /* Data range 10 to F0 */
#define COM15_R01FE         0x80  /*      01 to FE */
#define COM15_R00FF         0xc0  /*      00 to FF */
#define COM15_RGB565          0x10  /* RGB565 output */
#define COM15_RGB555          0x30  /* RGB555 output */
#define REG_COM16   0x41  /* Control 16 */
#define COM16_AWBGAIN         0x08  /* AWB gain enable */
#define REG_COM17   0x42  /* Control 17 */
#define COM17_AECWIN          0xc0  /* AEC window - must match COM4 */
#define COM17_CBAR          0x08  /* DSP Color bar */
/*
* This matrix defines how the colors are generated, must be
* tweaked to adjust hue and saturation.
*
* Order: v-red, v-green, v-blue, u-red, u-green, u-blue
* They are nine-bit signed quantities, with the sign bit
* stored in0x58.Sign for v-red is bit 0, and up from there.
*/
#define REG_CMATRIX_BASE  0x4f
#define CMATRIX_LEN           6
#define REG_CMATRIX_SIGN  0x58
#define REG_BRIGHT    0x55  /* Brightness */
#define REG_CONTRAS         0x56  /* Contrast control */
#define REG_GFIX    0x69  /* Fix gain control */
#define REG_REG76   0x76  /* OV's name */
#define R76_BLKPCOR         0x80  /* Black pixel correction enable */
#define R76_WHTPCOR         0x40  /* White pixel correction enable */
#define REG_RGB444          0x8c  /* RGB 444 control */
#define R444_ENABLE         0x02  /* Turn on RGB444, overrides 5x5 */
#define R444_RGBX   0x01  /* Empty nibble at end */
#define REG_HAECC1    0x9f  /* Hist AEC/AGC control 1 */
#define REG_HAECC2    0xa0  /* Hist AEC/AGC control 2 */
#define REG_BD50MAX         0xa5  /* 50hz banding step limit */
#define REG_HAECC3    0xa6  /* Hist AEC/AGC control 3 */
#define REG_HAECC4    0xa7  /* Hist AEC/AGC control 4 */
#define REG_HAECC5    0xa8  /* Hist AEC/AGC control 5 */
#define REG_HAECC6    0xa9  /* Hist AEC/AGC control 6 */
#define REG_HAECC7    0xaa  /* Hist AEC/AGC control 7 */
#define REG_BD60MAX         0xab  /* 60hz banding step limit */
#define REG_GAIN    0x00  /* Gain lower 8 bits (rest in vref) */
#define REG_BLUE    0x01  /* blue gain */
#define REG_RED           0x02  /* red gain */
#define REG_VREF    0x03  /* Pieces of GAIN, VSTART, VSTOP */
#define REG_COM1    0x04  /* Control 1 */
#define COM1_CCIR656          0x40  /* CCIR656 enable */
#define REG_BAVE    0x05  /* U/B Average level */
#define REG_GbAVE   0x06  /* Y/Gb Average level */
#define REG_AECHH   0x07  /* AEC MS 5 bits */
#define REG_RAVE    0x08  /* V/R Average level */
#define REG_COM2    0x09  /* Control 2 */
#define COM2_SSLEEP         0x10  /* Soft sleep mode */
#define REG_PID           0x0a  /* Product ID MSB */
#define REG_VER           0x0b  /* Product ID LSB */
#define REG_COM3    0x0c  /* Control 3 */
#define COM3_SWAP         0x40  /* Byte swap */
#define COM3_SCALEEN          0x08  /* Enable scaling */
#define COM3_DCWEN          0x04  /* Enable downsamp/crop/window */
#define REG_COM4    0x0d  /* Control 4 */
#define REG_COM5    0x0e  /* All "reserved" */
#define REG_COM6    0x0f  /* Control 6 */
#define REG_AECH    0x10  /* More bits of AEC value */
#define REG_CLKRC   0x11  /* Clocl control */
#define CLK_EXT           0x40  /* Use external clock directly */
#define CLK_SCALE   0x3f  /* Mask for internal clock scale */
#define REG_COM7    0x12  /* Control 7 */
#define COM7_RESET          0x80  /* Register reset */
#define COM7_FMT_MASK         0x38
#define COM7_FMT_VGA          0x00
#define COM7_FMT_CIF          0x20  /* CIF format */
#define COM7_FMT_QVGA         0x10  /* QVGA format */
#define COM7_FMT_QCIF         0x08  /* QCIF format */
#define COM7_RGB    0x04  /* bits 0 and 2 - RGB format */
#define COM7_YUV    0x00  /* YUV */
#define COM7_BAYER          0x01  /* Bayer format */
#define COM7_PBAYER         0x05  /* "Processed bayer" */
#define REG_COM8    0x13  /* Control 8 */
#define COM8_FASTAEC          0x80  /* Enable fast AGC/AEC */
#define COM8_AECSTEP          0x40  /* Unlimited AEC step size */
#define COM8_BFILT    0x20  /* Band filter enable */
#define COM8_AGC    0x04  /* Auto gain enable */
#define COM8_AWB    0x02  /* White balance enable */
#define COM8_AEC    0x01  /* Auto exposure enable */
#define REG_COM9    0x14  /* Control 9- gain ceiling */
#define REG_COM10   0x15  /* Control 10 */
#define COM10_HSYNC         0x40  /* HSYNC instead of HREF */
#define COM10_PCLK_HB         0x20  /* Suppress PCLK on horiz blank */
#define COM10_HREF_REV          0x08  /* Reverse HREF */
#define COM10_VS_LEAD           0x04  /* VSYNC on clock leading edge */
#define COM10_VS_NEG          0x02  /* VSYNC negative */
#define COM10_HS_NEG          0x01  /* HSYNC negative */
#define REG_HSTART    0x17  /* Horiz start high bits */
#define REG_HSTOP   0x18  /* Horiz stop high bits */
#define REG_VSTART    0x19  /* Vert start high bits */
#define REG_VSTOP   0x1a  /* Vert stop high bits */
#define REG_PSHFT   0x1b  /* Pixel delay after HREF */
#define REG_MIDH    0x1c  /* Manuf. ID high */
#define REG_MIDL    0x1d  /* Manuf. ID low */
#define REG_MVFP    0x1e  /* Mirror / vflip */
#define MVFP_MIRROR         0x20  /* Mirror image */
#define MVFP_FLIP   0x10  /* Vertical flip */
#define REG_AEW           0x24  /* AGC upper limit */
#define REG_AEB           0x25  /* AGC lower limit */
#define REG_VPT           0x26  /* AGC/AEC fast mode op region */
#define REG_HSYST   0x30  /* HSYNC rising edge delay */
#define REG_HSYEN   0x31  /* HSYNC falling edge delay */
#define REG_HREF    0x32  /* HREF pieces */
#define REG_TSLB    0x3a  /* lots of stuff */
#define TSLB_YLAST    0x04  /* UYVY or VYUY - see com13 */
#define REG_COM11   0x3b  /* Control 11 */
#define COM11_NIGHT         0x80  /* NIght mode enable */
#define COM11_NMFR          0x60  /* Two bit NM frame rate */
#define COM11_HZAUTO          0x10  /* Auto detect 50/60 Hz */
#define COM11_50HZ          0x08  /* Manual 50Hz select */
#define COM11_EXP   0x02
#define REG_COM12   0x3c  /* Control 12 */
#define COM12_HREF          0x80  /* HREF always */
#define REG_COM13   0x3d  /* Control 13 */
#define COM13_GAMMA         0x80  /* Gamma enable */
#define COM13_UVSAT         0x40  /* UV saturation auto adjustment */
#define COM13_UVSWAP          0x01  /* V before U - w/TSLB */
#define REG_COM14   0x3e  /* Control 14 */
#define COM14_DCWEN         0x10  /* DCW/PCLK-scale enable */
#define REG_EDGE    0x3f  /* Edge enhancement factor */
#define REG_COM15   0x40  /* Control 15 */
#define COM15_R10F0         0x00  /* Data range 10 to F0 */
#define COM15_R01FE         0x80  /*      01 to FE */
#define COM15_R00FF         0xc0  /*      00 to FF */
#define COM15_RGB565          0x10  /* RGB565 output */
#define COM15_RGB555          0x30  /* RGB555 output */
#define REG_COM16   0x41  /* Control 16 */
#define COM16_AWBGAIN         0x08  /* AWB gain enable */
#define REG_COM17   0x42  /* Control 17 */
#define COM17_AECWIN          0xc0  /* AEC window - must match COM4 */
#define COM17_CBAR          0x08  /* DSP Color bar */

#define CMATRIX_LEN             6
#define REG_BRIGHT    0x55  /* Brightness */
#define REG_REG76   0x76  /* OV's name */
#define R76_BLKPCOR         0x80  /* Black pixel correction enable */
#define R76_WHTPCOR         0x40  /* White pixel correction enable */
#define REG_RGB444          0x8c  /* RGB 444 control */
#define R444_ENABLE         0x02  /* Turn on RGB444, overrides 5x5 */
#define R444_RGBX   0x01  /* Empty nibble at end */
#define REG_HAECC1    0x9f  /* Hist AEC/AGC control 1 */
#define REG_HAECC2    0xa0  /* Hist AEC/AGC control 2 */
#define REG_BD50MAX         0xa5  /* 50hz banding step limit */
#define REG_HAECC3    0xa6  /* Hist AEC/AGC control 3 */
#define REG_HAECC4    0xa7  /* Hist AEC/AGC control 4 */
#define REG_HAECC5    0xa8  /* Hist AEC/AGC control 5 */
#define REG_HAECC6    0xa9  /* Hist AEC/AGC control 6 */
#define REG_HAECC7    0xaa  /* Hist AEC/AGC control 7 */
#define REG_BD60MAX         0xab  /* 60hz banding step limit */
#define MTX1            0x4f  /* Matrix Coefficient 1 */
#define MTX2            0x50  /* Matrix Coefficient 2 */
#define MTX3            0x51  /* Matrix Coefficient 3 */
#define MTX4            0x52  /* Matrix Coefficient 4 */
#define MTX5            0x53  /* Matrix Coefficient 5 */
#define MTX6            0x54  /* Matrix Coefficient 6 */
#define REG_CONTRAS         0x56  /* Contrast control */
#define MTXS            0x58  /* Matrix Coefficient Sign */
#define AWBC7           0x59  /* AWB Control 7 */
#define AWBC8           0x5a  /* AWB Control 8 */
#define AWBC9           0x5b  /* AWB Control 9 */
#define AWBC10            0x5c  /* AWB Control 10 */
#define AWBC11            0x5d  /* AWB Control 11 */
#define AWBC12            0x5e  /* AWB Control 12 */
#define REG_GFI           0x69  /* Fix gain control */
#define GGAIN           0x6a  /* G Channel AWB Gain */
#define DBLV            0x6b  
#define AWBCTR3           0x6c  /* AWB Control 3 */
#define AWBCTR2           0x6d  /* AWB Control 2 */
#define AWBCTR1           0x6e  /* AWB Control 1 */
#define AWBCTR0           0x6f  /* AWB Control 0 */

struct regval_list{
  uint8_t reg_num;
  uint16_t value;
};

const struct regval_list qvga_ov7670[] PROGMEM = {
  { REG_COM14, 0x19 },
  { 0x72, 0x11 },
  { 0x73, 0xf1 },

  { REG_HSTART, 0x16 },
  { REG_HSTOP, 0x04 },
  { REG_HREF, 0xa4 },
  { REG_VSTART, 0x02 },
  { REG_VSTOP, 0x7a },
  { REG_VREF, 0x0a },


/*  { REG_HSTART, 0x16 },
  { REG_HSTOP, 0x04 },
  { REG_HREF, 0x24 },
  { REG_VSTART, 0x02 },
  { REG_VSTOP, 0x7a },
  { REG_VREF, 0x0a },*/
  { 0xff, 0xff }, /* END MARKER */
};

const struct regval_list yuv422_ov7670[] PROGMEM = {
  { REG_COM7, 0x0 },  /* Selects YUV mode */
  { REG_RGB444, 0 },  /* No RGB444 please */
  { REG_COM1, 0 },
  { REG_COM15, COM15_R00FF },
  { REG_COM9, 0x6A }, /* 128x gain ceiling; 0x8 is reserved bit */
  { 0x4f, 0x80 },   /* "matrix coefficient 1" */
  { 0x50, 0x80 },   /* "matrix coefficient 2" */
  { 0x51, 0 },    /* vb */
  { 0x52, 0x22 },   /* "matrix coefficient 4" */
  { 0x53, 0x5e },   /* "matrix coefficient 5" */
  { 0x54, 0x80 },   /* "matrix coefficient 6" */
  { REG_COM13, COM13_UVSAT },
  { 0xff, 0xff },   /* END MARKER */
};

const struct regval_list ov7670_default_regs[] PROGMEM = {//from the linux driver
  { REG_COM7, COM7_RESET },
  { REG_TSLB, 0x04 }, /* OV */
  { REG_COM7, 0 },  /* VGA */
  /*
  * Set the hardware window.  These values from OV don't entirely
  * make sense - hstop is less than hstart.  But they work...
  */
  { REG_HSTART, 0x13 }, { REG_HSTOP, 0x01 },
  { REG_HREF, 0xb6 }, { REG_VSTART, 0x02 },
  { REG_VSTOP, 0x7a }, { REG_VREF, 0x0a },

  { REG_COM3, 0 }, { REG_COM14, 0 },
  /* Mystery scaling numbers */
  { 0x70, 0x3a }, { 0x71, 0x35 },
  { 0x72, 0x11 }, { 0x73, 0xf0 },
  { 0xa2,/* 0x02 changed to 1*/1 }, { REG_COM10, 0x0 },
  /* Gamma curve values */
  { 0x7a, 0x20 }, { 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 },
  /* AGC and AEC parameters.  Note we start by disabling those features,
  then turn them only after tweaking the values. */
  { REG_COM8, COM8_FASTAEC | COM8_AECSTEP },
  { REG_GAIN, 0 }, { REG_AECH, 0 },
  { REG_COM4, 0x40 }, /* magic reserved bit */
  { REG_COM9, 0x18 }, /* 4x gain + magic rsvd bit */
  { REG_BD50MAX, 0x05 }, { REG_BD60MAX, 0x07 },
  { REG_AEW, 0x95 }, { REG_AEB, 0x33 },
  { REG_VPT, 0xe3 }, { REG_HAECC1, 0x78 },
  { REG_HAECC2, 0x68 }, { 0xa1, 0x03 }, /* magic */
  { REG_HAECC3, 0xd8 }, { REG_HAECC4, 0xd8 },
  { REG_HAECC5, 0xf0 }, { REG_HAECC6, 0x90 },
  { REG_HAECC7, 0x94 },
  { REG_COM8, COM8_FASTAEC | COM8_AECSTEP | COM8_AGC | COM8_AEC },
  { 0x30, 0 }, { 0x31, 0 },//disable some delays
  /* Almost all of these are magic "reserved" values.  */
  { REG_COM5, 0x61 }, { REG_COM6, 0x4b },
  { 0x16, 0x02 }, { REG_MVFP, 0x07 },
  { 0x21, 0x02 }, { 0x22, 0x91 },
  { 0x29, 0x07 }, { 0x33, 0x0b },
  { 0x35, 0x0b }, { 0x37, 0x1d },
  { 0x38, 0x71 }, { 0x39, 0x2a },
  { REG_COM12, 0x78 }, { 0x4d, 0x40 },
  { 0x4e, 0x20 }, { REG_GFIX, 0 },
  /*{0x6b, 0x4a},*/{ 0x74, 0x10 },
  { 0x8d, 0x4f }, { 0x8e, 0 },
  { 0x8f, 0 }, { 0x90, 0 },
  { 0x91, 0 }, { 0x96, 0 },
  { 0x9a, 0 }, { 0xb0, 0x84 },
  { 0xb1, 0x0c }, { 0xb2, 0x0e },
  { 0xb3, 0x82 }, { 0xb8, 0x0a },

  /* More reserved magic, some of which tweaks white balance */
  { 0x43, 0x0a }, { 0x44, 0xf0 },
  { 0x45, 0x34 }, { 0x46, 0x58 },
  { 0x47, 0x28 }, { 0x48, 0x3a },
  { 0x59, 0x88 }, { 0x5a, 0x88 },
  { 0x5b, 0x44 }, { 0x5c, 0x67 },
  { 0x5d, 0x49 }, { 0x5e, 0x0e },
  { 0x6c, 0x0a }, { 0x6d, 0x55 },
  { 0x6e, 0x11 }, { 0x6f, 0x9e }, /* it was 0x9F "9e for advance AWB" */
  { 0x6a, 0x40 }, { REG_BLUE, 0x40 },
  { REG_RED, 0x60 },
  { REG_COM8, COM8_FASTAEC | COM8_AECSTEP | COM8_AGC | COM8_AEC | COM8_AWB },

  /* Matrix coefficients */
  { 0x4f, 0x80 }, { 0x50, 0x80 },
  { 0x51, 0 },    { 0x52, 0x22 },
  { 0x53, 0x5e }, { 0x54, 0x80 },
  { 0x58, 0x9e },

  { REG_COM16, COM16_AWBGAIN }, { REG_EDGE, 0 },
  { 0x75, 0x05 }, { REG_REG76, 0xe1 },
  { 0x4c, 0 },     { 0x77, 0x01 },
  { REG_COM13, /*0xc3*/0x48 }, { 0x4b, 0x09 },
  { 0xc9, 0x60 },   /*{REG_COM16, 0x38},*/
  { 0x56, 0x40 },

  { 0x34, 0x11 }, { REG_COM11, COM11_EXP | COM11_HZAUTO },
  { 0xa4, 0x82/*Was 0x88*/ }, { 0x96, 0 },
  { 0x97, 0x30 }, { 0x98, 0x20 },
  { 0x99, 0x30 }, { 0x9a, 0x84 },
  { 0x9b, 0x29 }, { 0x9c, 0x03 },
  { 0x9d, 0x4c }, { 0x9e, 0x3f },
  { 0x78, 0x04 },

  /* Extra-weird stuff.  Some sort of multiplexor register */
  { 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 },
  { 0xff, 0xff }, /* END MARKER */
};


void error_led(void){
  DDRB |= 32;//make sure led is output
  while (1){//wait for reset
    PORTB ^= 32;// toggle led
    _delay_ms(100);
  }
}

void twiStart(void){
  TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN);//send start
  while (!(TWCR &amp; (1 &lt;&lt; TWINT)));//wait for start to be transmitted
  if ((TWSR &amp; 0xF8) != TW_START)
    error_led();
}

void twiWriteByte(uint8_t DATA, uint8_t type){
  TWDR = DATA;
  TWCR = _BV(TWINT) | _BV(TWEN);
  while (!(TWCR &amp; (1 &lt;&lt; TWINT))) {}
  if ((TWSR &amp; 0xF8) != type)
    error_led();
}

void twiAddr(uint8_t addr, uint8_t typeTWI){
  TWDR = addr;//send address
  TWCR = _BV(TWINT) | _BV(TWEN);    /* clear interrupt to start transmission */
  while ((TWCR &amp; _BV(TWINT)) == 0); /* wait for transmission */
  if ((TWSR &amp; 0xF8) != typeTWI)
    error_led();
}

void wrReg(uint8_t reg, uint8_t dat){
  //send start condition
  twiStart();
  twiAddr(camAddr_WR, TW_MT_SLA_ACK);
  twiWriteByte(reg, TW_MT_DATA_ACK);
  twiWriteByte(dat, TW_MT_DATA_ACK);
  TWCR = (1 &lt;&lt; TWINT) | (1 &lt;&lt; TWEN) | (1 &lt;&lt; TWSTO);//send stop
  _delay_ms(1);
}

static uint8_t twiRd(uint8_t nack){
  if (nack){
    TWCR = _BV(TWINT) | _BV(TWEN);
    while ((TWCR &amp; _BV(TWINT)) == 0); /* wait for transmission */
    if ((TWSR &amp; 0xF8) != TW_MR_DATA_NACK)
      error_led();
    return TWDR;
  }
  else{
    TWCR = _BV(TWINT) | _BV(TWEN) | _BV(TWEA);
    while ((TWCR &amp; _BV(TWINT)) == 0); /* wait for transmission */
    if ((TWSR &amp; 0xF8) != TW_MR_DATA_ACK)
      error_led();
    return TWDR;
  }
}

uint8_t rdReg(uint8_t reg){
  uint8_t dat;
  twiStart();
  twiAddr(camAddr_WR, TW_MT_SLA_ACK);
  twiWriteByte(reg, TW_MT_DATA_ACK);
  TWCR = (1 &lt;&lt; TWINT) | (1 &lt;&lt; TWEN) | (1 &lt;&lt; TWSTO);//send stop
  _delay_ms(1);
  twiStart();
  twiAddr(camAddr_RD, TW_MR_SLA_ACK);
  dat = twiRd(1);
  TWCR = (1 &lt;&lt; TWINT) | (1 &lt;&lt; TWEN) | (1 &lt;&lt; TWSTO);//send stop
  _delay_ms(1);
  return dat;
}

void wrSensorRegs8_8(const struct regval_list reglist[]){
  uint8_t reg_addr, reg_val;
  const struct regval_list *next = reglist;
  while ((reg_addr != 0xff) | (reg_val != 0xff)){
    reg_addr = pgm_read_byte(&amp;next-&gt;reg_num);
    reg_val = pgm_read_byte(&amp;next-&gt;value);
    wrReg(reg_addr, reg_val);
    next++;
  }
}

void setColor(void){
  wrSensorRegs8_8(yuv422_ov7670);
}

void setRes(void){
  wrReg(REG_COM3, 4); // REG_COM3 enable scaling
  wrSensorRegs8_8(qvga_ov7670);
}

void camInit(void){
  wrReg(0x12, 0x80);
  _delay_ms(100);
  wrSensorRegs8_8(ov7670_default_regs);
  wrReg(REG_COM10, 32);//PCLK does not toggle on HBLANK.
}

void arduinoUnoInut(void) {
  cli();//disable interrupts

    /* Setup the 8mhz PWM clock
  * This will be on pin 11*/
  DDRB |= (1 &lt;&lt; 3);//pin 11
  ASSR &amp;= ~(_BV(EXCLK) | _BV(AS2));
  TCCR2A = (1 &lt;&lt; COM2A0) | (1 &lt;&lt; WGM21) | (1 &lt;&lt; WGM20);
  TCCR2B = (1 &lt;&lt; WGM22) | (1 &lt;&lt; CS20);
  OCR2A = 0;//(F_CPU)/(2*(X+1))
  DDRC &amp;= ~15;//low d0-d3 camera
  DDRD &amp;= ~252;//d7-d4 and interrupt pins
  _delay_ms(3000);

    //set up twi for 100khz
  TWSR &amp;= ~3;//disable prescaler for TWI
  TWBR = 72;//set to 100khz

    //enable serial
  UBRR0H = 0;
  UBRR0L = 1;//0 = 2M baud rate. 1 = 1M baud. 3 = 0.5M. 7 = 250k 207 is 9600 baud rate.
  UCSR0A |= 2;//double speed aysnc
  UCSR0B = (1 &lt;&lt; RXEN0) | (1 &lt;&lt; TXEN0);//Enable receiver and transmitter
  UCSR0C = 6;//async 1 stop bit 8bit char no parity bits
}


void StringPgm(const char * str){
  do{
      while (!(UCSR0A &amp; (1 &lt;&lt; UDRE0)));//wait for byte to transmit
      UDR0 = pgm_read_byte_near(str);
      while (!(UCSR0A &amp; (1 &lt;&lt; UDRE0)));//wait for byte to transmit
  } while (pgm_read_byte_near(++str));
}

static void captureImg(uint16_t wg, uint16_t hg){
  uint16_t y, x;

  StringPgm(PSTR("*RDY*"));

  while (!(PIND &amp; 8));//wait for high
  while ((PIND &amp; 8));//wait for low

    y = hg;
  while (y--){
        x = wg;
      //while (!(PIND &amp; 256));//wait for high
    while (x--){
      while ((PIND &amp; 4));//wait for low
            UDR0 = (PINC &amp; 15) | (PIND &amp; 240);
          while (!(UCSR0A &amp; (1 &lt;&lt; UDRE0)));//wait for byte to transmit
      while (!(PIND &amp; 4));//wait for high
      while ((PIND &amp; 4));//wait for low
      while (!(PIND &amp; 4));//wait for high
    }
    //  while ((PIND &amp; 256));//wait for low
  }
    _delay_ms(100);
}

void setup(){
  arduinoUnoInut();
  camInit();
  setRes();
  setColor();
  wrReg(0x11, 11); //Earlier it had the value: wrReg(0x11, 12); New version works better for me :) !!!!
}


void loop(){
  captureImg(320, 240);
}
</code></pre>

<p>The sketch has way too many <code>#define</code>s, and isn't exactly straightforward, but at least it loads, although there is one warning:</p>

<pre><code>/Users/charles/Documents/Arduino/cameraTest2/cameraTest2.ino:13:0: warning: "F_CPU" redefined
 #define F_CPU 16000000UL
 ^
&lt;command-line&gt;:0:0: note: this is the location of the previous definition
</code></pre>

<p>To validate that this does anything, I tried playing around with <a href="https://github.com/ComputerNerd/simpleFrameGrabber" rel="nofollow noreferrer">ComputerNerd's SimpleFrameGrabber</a>, but I'm on a mac and I ran into problems when trying to <code>./build</code>:</p>

<pre><code>main.c:26:10: fatal error: 'SDL/SDL.h' file not found
#include &lt;SDL/SDL.h&gt;
</code></pre>

<p>I then tried opening up the Arduino IDE Serial Monitor, and am not seeing anything. Should I be seeing anything? I was expecting I would at least see gibberish..</p>

<p>Ideally, I would like to find some simple example code that would setup the camera (the defaults might even be just fine), and allow me to get RGB pixel data for a 320x240 or 640x480 image. If I could just print that to the Serial Output, I could then write a simple python script to save it as a jpg or a png or something. </p>

<p>I just need to get to a sanity state with this thing. Or find another inexpensive camera module that's easier to work with.</p>
 4628: <pre><code>//enable serial
UBRR0H = 0;
UBRR0L = 1;//0 = 2M baud rate. 1 = 1M baud. 3 = 0.5M. 7 = 250k 207 is 9600 baud rate.
UCSR0A |= 2;//double speed aysnc
UCSR0B = (1 &lt;&lt; RXEN0) | (1 &lt;&lt; TXEN0);//Enable receiver and transmitter
UCSR0C = 6;//async 1 stop bit 8bit char no parity bits
</code></pre>

<p>This bit enables Serial (Rx=0, Tx=1) at 1M baud. Is the Serial Monitor set to the right baud rate?</p>
