OV7670 Camera Module

The OV7670/OV7171 CAMERACHIPTM is a low voltage CMOS image sensor that provides the full functionality of a single-chip VGA camera and image processor in a small footprint package. The OV7670/OV7171 provides full-frame, sub-sampled or windowed 8-bit images in a wide range of formats, controlled through the Serial Camera Control Bus (SCCB) interface.

This product has an image array capable of operating at up to 30 frames per second (fps) in VGA with complete user control over image quality, formatting and output data transfer. All required image processing functions, including exposure control, gamma, white balance, color saturation, hue control and more, are also programmable through the SCCB interface. In addition, Omni Vision CAMERACHIPs use proprietary sensor technology to improve image quality by reducing or eliminating common lighting/electrical sources of image contamination, such as fixed pattern noise (FPN), smearing, blooming, etc., to produce a clean, fully stable color image.

Features:

Optical size 1/6 inch
High sensitivity for low-light operation
Low operating voltage for embedded portable apps
Standard SCCB interface compatible with I2C interface
VarioPixel® method for sub-sampling Ø Automatic image control functions including: Automatic
Image quality controls including color saturation, hue, gamma, sharpness (edge enhancement), and anti-blooming
ISP includes noise reduction and defect correction
Supports LED and flash strobe mode
Supports scaling
Lens shading correction
Flicker (50/60 Hz) auto detection
Saturation level auto adjust (UV adjust)
Edge enhancement level auto adjust
De-noise level auto adjust 0.3M Pixels CMOS

Specification:

Resolution 640×480 VGA
Onboard regulator, only single 3.3V supply needed
Standard 0.1inch (2.54mm) pin pitch header connector
Mounted with high quality F1.8 / 6mm lens
Output support for Raw RGB, RGB (GRB 4:2:2, RGB565/555/444), YUV (4:2:2) and YCbCr (4:2:2) formats
Supports image sizes: VGA, CIF, and any size scaling down from CIF to 40×30
Exposure Control (AEC), Automatic Gain Control (AGC), Automatic White Balance (AWB), Automatic
Band Filter (ABF), and Automatic Black-Level Calibration (ABLC)

Interfacing with Arduino:

Code:

#define F_CPU 16000000UL

#include <stdint.h>

#include <avr/io.h>

#include <avr/interrupt.h>

#include <util/twi.h>

#include <util/delay.h>

#include <avr/pgmspace.h>

#include “ov7670.h”

/* Configuration: this lets you easily change between different resolutions

* You must only uncomment one

* no more no less*/

#define useVga

//#define useQvga

//#define useQqvga

static inline void serialWrB(uint8_t dat){

while(!( UCSR0A & (1<<UDRE0)));//wait for byte to transmit

UDR0=dat;

while(!( UCSR0A & (1<<UDRE0)));//wait for byte to transmit

}

static void StringPgm(const char * str){

do{

serialWrB(pgm_read_byte_near(str));

}while(pgm_read_byte_near(++str));

}

static void captureImg(uint16_t wg,uint16_t hg){

uint16_t lg2;

#ifdef useQvga

uint8_t buf[640];

#elif defined(useQqvga)

uint8_t buf[320];

#endif

StringPgm(PSTR(“RDY”));

//Wait for vsync it is on pin 3 (counting from 0) portD

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

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

#ifdef useVga

while(hg–){

lg2=wg;

while(lg2–){

while((PIND&4));//wait for low

UDR0=(PINC&15)|(PIND&240);

while(!(PIND&4));//wait for high

}

#elif defined(useQvga)

/*We send half of the line while reading then half later */

while(hg–){

uint8_t*b=buf,*b2=buf;

lg2=wg/2;

while(lg2–){

while((PIND&4));//wait for low

*b++=(PINC&15)|(PIND&240);

while(!(PIND&4));//wait for high

while((PIND&4));//wait for low

*b++=(PINC&15)|(PIND&240);

UDR0=*b2++;

while(!(PIND&4));//wait for high

}

/* Finish sending the remainder during blanking */

lg2=wg/2;

while(!( UCSR0A & (1<<UDRE0)));//wait for byte to transmit

while(lg2–){

UDR0=*b2++;

while(!( UCSR0A & (1<<UDRE0)));//wait for byte to transmit

}

#else

/* This code is very similar to qvga sending code except we have even more blanking time to take advantage of */

while(hg–){

uint8_t*b=buf,*b2=buf;

lg2=wg/5;

while(lg2–){

while((PIND&4));//wait for low

*b++=(PINC&15)|(PIND&240);

while(!(PIND&4));//wait for high

while((PIND&4));//wait for low

*b++=(PINC&15)|(PIND&240);

while(!(PIND&4));//wait for high

while((PIND&4));//wait for low

*b++=(PINC&15)|(PIND&240);

while(!(PIND&4));//wait for high

while((PIND&4));//wait for low

*b++=(PINC&15)|(PIND&240);

while(!(PIND&4));//wait for high

while((PIND&4));//wait for low

*b++=(PINC&15)|(PIND&240);

UDR0=*b2++;

while(!(PIND&4));//wait for high

}

/* Finish sending the remainder during blanking */

lg2=320-(wg/5);

while(!( UCSR0A & (1<<UDRE0)));//wait for byte to transmit

while(lg2–){

UDR0=*b2++;

while(!( UCSR0A & (1<<UDRE0)));//wait for byte to transmit

}

#endif

}

int main(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

camInit();

#ifdef useVga

setRes(VGA);

setColorSpace(BAYER_RGB);

wrReg(0x11,25);

#elif defined(useQvga)

setRes(QVGA);

setColorSpace(YUV422);

wrReg(0x11,12);

#else

setRes(QQVGA);

setColorSpace(YUV422);

wrReg(0x11,3);

#endif

/* If you are not sure what value to use here for the divider (register 0x11)

* Values I have found to work raw vga 25 qqvga yuv422 12 qvga yuv422 21

* run the commented out test below and pick the smallest value that gets a correct image */

while (1){

/* captureImg operates in bytes not pixels in some cases pixels are two bytes per pixel

* So for the width (if you were reading 640×480) you would put 1280 if you are reading yuv422 or rgb565 */

/*uint8_t x=63;//Uncomment this block to test divider settings note the other line you need to uncomment

do{

wrReg(0x11,x);

_delay_ms(1000);*/

#ifdef useVga

captureImg(640,480);

#elif defined(useQvga)

captureImg(320*2,240);

#else

captureImg(160*2,120);

#endif

//}while(–x);//Uncomment this line to test divider settings

}

Application:

Cellular phones
PDAs
Toys
Other battery-powered products
Can be used in Arduino, Maple, ChipKit, STM32, ARM, DSP, FPGA

Reference:

https://www.openhacks.com/uploadsproductos/ov7670_cmos_camera_module_revc_ds.pdf

https://forum.arduino.cc/index.php?topic=20828.0

https://circuitdigest.com/microcontroller-projects/how-to-use-ov7670-camera-module-with-arduino

https://www.instructables.com/id/OV7670-Arduino-Camera-Sensor-Module-Framecapture-T/