camera-configuration.c

#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#include <errno.h>
#include <unistd.h>
#include <getopt.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
//#include <linux/i2c.h>	
#include <linux/i2c-dev.h>
#include <sys/ioctl.h>
#include <stdint.h>

#define I2C_CHANNEL "/dev/i2c-12"
#define LEGACY_I2C_CHANNEL "/dev/i2c-4"
#define OV7670_ADDR 0x21

/*######################
## OV7670 registers ##
######################
*/
#define REG_CLKRC 0x11 		// Clocl control
#define REG_COM7 0x12 		// Control 7
#define REG_COM10 0x15 		// Control 10
#define COM7_FMT_VGA 0x00
#define COM7_YUV 0x00 		// YUV
#define COM7_RGB 0x04 		// bits 0 and 2 - RGB format
#define REG_TSLB 0x3a 		// lots of stuff
#define REG_COM11 0x3b 		// Control 11
#define REG_COM15 0x40 		// Control 15
#define COM15_R00FF 0xc0 	// 00 to FF
#define COM15_RGB565 0x10 	// RGB565 output
#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_VREF 0x03 		// Pieces of GAIN, VSTART, VSTOP
#define REG_HREF 0x32 		// HREF pieces
#define REG_RGB444 0x8c 	// RGB 444 control
#define REG_COM9 0x14 		// Control 9  - gain ceiling
#define REG_COM13 0x3d 		// Control 13
#define COM13_GAMMA 0x80 	// Gamma enable
#define COM13_UVSAT 0x40 	// UV saturation auto adjustment

int file = -1;
uint8_t data[2];
uint32_t sensor_id = 0;

int write_i2c(uint8_t reg, uint8_t val) {
	uint8_t buf[2] = {reg, val};
	int trials = 0;
	while(trials < 5) {
		if (write(file, &buf, 2) != 2) {
			//printf("Failed writing register 0x%02x!\n", reg);
			trials++;
			usleep(200000);
		} else {
			break;
		}
	}
	if(trials == 5) {
		return -1;
	}
	return 0;
}

int read_i2c(uint8_t reg, uint8_t *val) {
	int trials = 0;
	while(trials < 5) {
		if (write(file, &reg, 1) != 1) {
			//printf("Failed writing register 0x%02x!\n", reg);
			trials++;
			usleep(200000);
		} else {
			break;
		}
	}
	if(trials == 5) {
		return -1;
	}	
	trials = 0;
	while(trials < 5) {
		if (read(file, val, 1) != 1) {
			//printf("Failed reading 0x%02x!\n", *val);
			trials++;
			usleep(200000);
		} else {
			break;
		}
	}
	if(trials == 5) {
		return -1;
	}	
	return 0;
}

int ov7670_init(void) {
	if(write_i2c(REG_COM7, 0x80) < 0) { // Reset to default values.
		return -1;
	}
	usleep(200000);
	if(write_i2c(REG_CLKRC, 0x80) < 0) { // No internal clock prescaler.
		return -1;
	}	
	if(write_i2c(REG_TSLB, 0x04) < 0) {  // 0x04 = 0x0c (default) but with YUYV
		return -1;
	}		
	if(write_i2c(REG_COM7, COM7_YUV|COM7_FMT_VGA) < 0) {  // Output format: YUV, VGA.
		return -1;
	}	
	if(write_i2c(REG_COM15, COM15_R00FF) < 0) { 
		return -1;
	}	
	if(write_i2c(REG_COM13, 0x00) < 0) { // YUYV
		return -1;
	}
	if(write_i2c(0xb0, 0x84) < 0) {  // Color mode?? (Not documented!)
		return -1;
	}	
	
	if(write_i2c(REG_HSTART, 0x13) < 0) { 	// start = HSTART<<3 + HREF[2:0] = 19*8 + 6 = 158
		return -1;
	}	
	if(write_i2c(REG_HSTOP, 0x01) < 0) {  	// stop = HSTOP<<3 + HREF[5:3] = 1*8 + 6 = 14 (158+640-784)
		return -1;
	}	
	if(write_i2c(REG_HREF, 0x36) < 0) {  		// With flag "edge offset" set, then the image is strange (too much clear, not sharp); so clear this bit.
		return -1;
	}	
	if(write_i2c(REG_VSTART, 0x02) < 0) {  	// start = VSTART<<2 + VREF[1:0] = 2*4 + 2 = 10
		return -1;
	}	
	if(write_i2c(REG_VSTOP, 0x7a) < 0) {  	// stop = VSTOP<<2 + VREF[3:2] = 122*4 + 2 = 490
		return -1;
	}	
	if(write_i2c(REG_VREF, 0x0a) < 0) {  
		return -1;
	}	

	// Output array is 784x510 => 21'000'000 / (784x510x2) = about 26 fps
	// To lower the framerate to 15 fps we insert dummy pixels and dummy rows: 21'000'000 / [(784+91)x(510+290)x2] = 15 fps
	if(write_i2c(0x2a, 0x00) < 0) {  // Dummy pixels MSB
		return -1;
	}
	if(write_i2c(0x2b, 0x5B) < 0) {  // Dummy pixels LSB
		return -1;
	}
	if(write_i2c(0x92, 0x22) < 0) {  // Dummy rows LSB
		return -1;
	}
	if(write_i2c(0x93, 0x01) < 0) {  // Dummy rows LSB
		return -1;
	}
	
	if(write_i2c(0x0c, 0x00) < 0) { 
		return -1;
	}	
	if(write_i2c(0x3e, 0x00) < 0) { 
		return -1;
	}	
	if(write_i2c(0x70, 0x3a) < 0) { 
		return -1;
	}	
	if(write_i2c(0x71, 0x35) < 0) { 
		return -1;
	}	
	if(write_i2c(0x72, 0x11) < 0) { 
		return -1;
	}	
	if(write_i2c(0x73, 0xf0) < 0) { 
		return -1;
	}	
	if(write_i2c(0xa2, 0x02) < 0) { 
		return -1;
	}	
	
	return 0;
}

int main(int argc, char *argv[]) {

	file = open(I2C_CHANNEL, O_RDWR);
	if(file < 0) { // Try with bus number used in older kernel
		file = open(LEGACY_I2C_CHANNEL, O_RDWR);	
		if(file < 0) {
			perror("Cannot open I2C camera device");
			exit(1);
		}
	}
	
	/* open device to communicate with */
	//if (ioctl(file, I2C_SLAVE_FORCE, OV7670_ADDR) < 0) {
	if (ioctl(file, I2C_SLAVE, OV7670_ADDR) < 0) {
		/* ERROR HANDLING; you can check errno to see what went wrong */
		printf("Error setting slave device\n");
		close(file);
		exit(1);
	}	
	
	if(read_i2c(0x0a, &data[0]) < 0) {
		return -1;
	}
	if(read_i2c(0x0b, &data[1]) < 0) {
		return -1;
	}

	sensor_id = (data[0] << 8) + data[1];

	//printf("Read data: 0x%.4x\r\n", sensor_id);

	if (sensor_id == 0x7673) {
		printf("Detected camera sensor: OV7670\r\n");
		return ov7670_init();
	} else {
		return -1;
	}

	return 0;
	
}