while (1):
    if uart.any():
        receive=uart.readline().decode()
        if receive=='N':                #when receive 'N',begin to find the color
            threshold_index=0           #red for 0
            print(receive)
            while(True):
                img = sensor.snapshot() # Take a picture and return the image.

                blobs = img.find_blobs([thresholds[threshold_index]])
                if blobs:
                    max_blob=find_max(blobs)
                    img.draw_rectangle(max_blob.rect())
                    img.draw_cross(max_blob.cx(), max_blob.cy())
                    aim=1                #1 find the aim,0 not find
                    a=max_blob.cx()
                    b=max_blob.cy()

                    #transfer the format become(x,xxx,xxx)
                    if max_blob.cx()<10:
                        a='00'+str(a)
                        if max_blob.cy()<10:
                            b='00'+str(b)
                    elif max_blob.cy()<10:
                        b='00'+str(b)               #the case that max_blob.cx or .cy<10

                    elif max_blob.cx()<100:
                        a='0'+str(a)
#                         print(a)
                        if max_blob.cy()<100:
                            b='0'+str(b)
                    elif max_blob.cy()<100:
                        b='0'+str(b)                #the case that max_blob.cx or .cy<100

                    output_str="[%s,%s,%s]" % (aim,a,b)
                    print('you send:',output_str)
                    uart.write(output_str+'\r\n')      #the output foemat is (x,xxx,xxx)
                else:
                    aim=0
                    aim="[%s]"%(aim)
                    uart.write(aim+'\r\n')
                    print('not found!')

                if uart.any():
                    receiv=uart.readline().decode()
                    if receiv=='G':                  #the command is the symbol of find green
                        threshold_index=2            #green for 2
                        while(True):
                            img = sensor.snapshot() # Take a picture and return the image.

                            blobs = img.find_blobs([thresholds[threshold_index]])
                            if blobs:
                                max_blob=find_max(blobs)
                                img.draw_rectangle(max_blob.rect())
                                img.draw_cross(max_blob.cx(), max_blob.cy())
                                aim=1                #1 find the aim,0 not find
                                a=max_blob.cx()
                                b=max_blob.cy()

                                #transfer the format become(x,xxx,xxx)
                                if max_blob.cx()<10:
                                    a='00'+str(a)
                                    if max_blob.cy()<10:
                                        b='00'+str(b)
                                elif max_blob.cy()<10:
                                    b='00'+str(b)               #the case that max_blob.cx or .cy<10

                                elif max_blob.cx()<100:
                                    a='0'+str(a)
                                    print(a)
                                    if max_blob.cy()<100:
                                        b='0'+str(b)
                                elif max_blob.cy()<100:
                                    b='0'+str(b)                #the case that max_blob.cx or .cy<100

                                output_str="[%s,%s,%s]" % (aim,a,b)
                                print('send:',output_str)
                                uart.write(output_str+'\r\n')      #the output foemat is (x,xxx,xxx)
                            else:
                                aim=0
                                aim="[%s]"%(aim)
                                uart.write(aim+'\r\n')
                                print('not found!')