File content as of revision 2:c10029b87439:

#if 1
// example2_LogitechC270.cpp
//
// simple color tracking
//
#include "mbed.h"
#include "rtos.h"
#include "BaseUsbHost.h"
#include "LogitechC270.h"
#include "UvcCam.h"
#include "BaseJpegDecode.h"
#include "Terminal.h"
#include "MyThread.h"

// Logitech C270
#define WIDTH  160
#define HEIGHT 120

#define THRESHOLD 200

DigitalOut led1(LED1), led2(LED2), led3(LED3), led4(LED4);
Terminal term(USBTX, USBRX);

class CalcCenter : public MyThread, public BaseJpegDecode {
public:
    int y_center, x_center;
    int m_x_sum, m_y_sum, m_sum;
    uint32_t EOI_count;
    int16_t buf_Cb[WIDTH/16*HEIGHT/8]; // debug
    int16_t buf_Cr[WIDTH/16*HEIGHT/8]; // debug
    CalcCenter(BaseUvc* cam) {
        m_cam = cam;
        m_cam->setOnResult(this, &CalcCenter::callback_motion_jpeg);
        EOI_count = 0;
    }
protected:
    void callback_motion_jpeg(uint16_t frame, uint8_t* buf, int len) {
        input(buf+12, len-12);
        if (buf[1]&1) { // FID
            led1 = !led1;
        }
    }
    
    virtual void outputDC(int mcu, int block, int value) {
        if (mcu >= (WIDTH/16*HEIGHT/8)) {
            return;
        }
        if (block == 2) {
            buf_Cb[mcu] = value * qt[1][0];
        } else if (block == 3) { // 0-1:Y 2:Cb 3:Cr
            buf_Cr[mcu] = value * qt[1][0];
            value *= qt[1][0];
            if (value >= THRESHOLD) { // red
                m_x_sum += value*(mcu%(WIDTH/16));
                m_y_sum += value*(mcu/(WIDTH/16));
                m_sum += value;
            }
        }
    }
    virtual void outputAC(int mcu, int block, int scan, int value){};
    virtual void outputMARK(uint8_t c){
        if (c == 0xd9) { // EOI
            if(m_sum == 0) {
                x_center = y_center = -1; // not found
            } else {
                x_center = m_x_sum / m_sum;
                y_center = m_y_sum / m_sum;
            }
            m_x_sum = m_y_sum = m_sum = 0; // reset
            EOI_count++;
            led3 = !led3;
        }
    }

    virtual void run() {
        while(true) {
            if (m_cam) {
                m_cam->poll();
            }
        }
    }
    BaseUvc* m_cam;
};

BaseUvc* cam = NULL;
CalcCenter* calc = NULL;

#define PI 3.14159265

class display_Thread : public MyThread {
    virtual void run() {
        term.cls();
        int fg, old_fg = 0xffffff;
        while(1) {
            int column = 0;
            for(int y = 0; y < HEIGHT/8; y++) {
                term.locate(0, column++);
                for(int x = 0; x < WIDTH/16; x++) {
                    int value = calc->buf_Cr[y*WIDTH/16+x];
                    if (value >= THRESHOLD) {
                        fg = 0xff0000; // red
                    } else {
                        fg = 0xffffff; // white
                    }
                    if (fg != old_fg) {
                        term.foreground(fg);
                        old_fg = fg;
                    }
                    term.printf("%+4d,", value);
                }
            }
            term.locate(0, column++);
            term.printf("Cr:(%d,%d)", calc->x_center, calc->y_center);
#if 0            
            for(int y = 0; y < HEIGHT/8; y++) {
                term.locate(0, column++);
                for(int x = 0; x < WIDTH/16; x++) {
                    float Cb = calc->buf_Cb[y*WIDTH/16+x];
                    float Cr = calc->buf_Cr[y*WIDTH/16+x];
                    float value;
                    if (Cb == 0.0) {
                        value = 0.0;
                    } else {
                        value = (atan(Cr / Cb) + PI/2.0)* 360.0 / PI;
                    }
                    term.printf("%3.0f,", value);
                }
            }
#endif
            term.locate(0, column++);
            term.printf("width=%d height=%d yblock=%d EOI: %u]\n", 
                         calc->width, calc->height, calc->yblock, calc->EOI_count);
            term.printf("CC:"); 
            for(int i = 0; i < 16; i++) {
                term.printf(" %u", cam->report_cc_count[i]); 
            }
            term.printf("]\n"); 
            term.printf("PS:"); 
            for(int i = 0; i < 16; i++) {
                term.printf(" %u", cam->report_ps_cc_count[i]); 
            }
            term.printf("]\n"); 
            Thread::wait(200);
            led2 = !led2;
        }
    }
};

int main() {
    term.baud(921600);
    term.printf("%s\n", __FILE__);

    BaseUsbHost* UsbHost = new BaseUsbHost;
    UsbHub* hub = new UsbHub();

    for(int port = 1; port <= MAX_HUB_PORT; port++) {
        ControlEp* ctlEp = hub->GetPortEp(port);
        if (LogitechC270::check(ctlEp)) {
            cam = new LogitechC270(C270_160x120, _10FPS, ctlEp); 
            break;
        }
        if (UvcCam::check(ctlEp)) {
            cam = new UvcCam(UVC_MJPEG, UVC_160x120, _10FPS, ctlEp); 
            break;
        }
    }
    if (cam == NULL) {
        error("USB camera not found\n");
    }
    calc = new CalcCenter(cam);
    calc->start();

    display_Thread* th = new display_Thread;
    th->start(osPriorityBelowNormal);

    Thread::wait(osWaitForever);
}
#endif