openmv串口处理数据问题

[3icr]

在openmv中，当外界通过串口向openmv发送‘1’时，openmv会一直开启工作模式，但是在我写的程序中，在串口接收到数据中为什么只有执行一次，为什么不能无限执行

import sensor, image, time
from pyb import UART



uart = UART(3, 115200)




green_threshold   = (14, 80, 19, -25, -67, -24)
#(35, 75, -7, -22, -47, -20)
#(36, 76, -88, 65, -110, -21)
#(27, 80, 15, -22, -47, -20)
#(18, 74, 53, -91, -78, -24)


sensor.reset() # Initialize the camera sensor.

sensor.set_pixformat(sensor.RGB565) # use RGB565.

sensor.set_framesize(sensor.QQVGA) # use QQVGA for speed.

sensor.skip_frames(10) # Let new settings take affect.

sensor.set_auto_whitebal(False) # turn this off.

#关闭白平衡。白平衡是默认开启的，在颜色识别中，需要关闭白平衡。
def delay1():#对画面进行延迟，不影响ide中的画面流畅度，并对串口发送数据进行延迟
    for i in range(45):
        sensor.snapshot()
        if i == 42:
            uart.write('1')

def delay2():#对画面进行延迟，不影响ide中的画面流畅度，并对串口发送数据进行延迟
    for i in range(45):
        sensor.snapshot()
        if i == 42:
            uart.write('2')

def delay3():#对画面进行延迟，不影响ide中的画面流畅度，并对串口发送数据进行延迟
    for i in range(45):
        sensor.snapshot()
        if i == 42:
            uart.write('3')

def delay4():#对画面进行延迟，不影响ide中的画面流畅度，并对串口发送数据进行延迟
    for i in range(45):
        sensor.snapshot()
        if i == 42:
            uart.write('4')

def delay5():#对画面进行延迟，不影响ide中的画面流畅度，并对串口发送数据进行延迟
    for i in range(45):
        sensor.snapshot()
        if i == 42:
            uart.write('5')

clock = time.clock() # Tracks FPS.

def find_c(threshold,roi):

     number=0
     max_size=0

     blobs = img.find_blobs(threshold,roi=roi,x_stride=10, y_stride=50)

     for b in blobs:

         if b[2]*b[3] > max_size:

             max_size = b[2]*b[3]

             if max_size>200 and b[2]>20:

                 if b[3]>20 and b[2]>20:

                     max_size=max_size

                     img.draw_rectangle(b[0:4], color = (0, 0, 0))

                     img.draw_cross(b[5], b[6], color = (0, 0, 0))
                     number=b[5]

     return number
def read():
    a=0
    if uart.any():
        a=int(uart.read())
        print(a)
    return a

def find_max(blobs):
    max_size=0
    max_blob=[]
    for blob in blobs:
        if blob[2]*blob[3] > max_size:
            max_blob=blob
            max_size = blob[2]*blob[3]
    return max_blob

def max_area(blobs):
    max_size=0
    max_blob=[]
    for blob in blobs:
        if blob[2]*blob[3] > max_size:
            max_blob=blob
            max_size = blob[2]*blob[3]
    return max_size
t=0
b=0
a=1
while(True):

    clock.tick() # Track elapsed milliseconds between snapshots().
    img = sensor.snapshot() # Take a picture and return the image.
    blobs = img.find_blobs([green_threshold])
    roi1=[0,0,40,120]
    roi2=[120,0,40,120]
    blobs3 = img.find_blobs([green_threshold],roi=roi2)
    blobs2 = img.find_blobs([green_threshold],roi=roi1)
    #if uart.any():
       # a=int(uart.read())
       # print(a)
    #return a
    if b==0:
        a=read()
        if a==1:
            b=1
        elif a==2:
            b=2
        elif a==3:
            b=3


    #if  blobs:
    if b==1 and t==0:
        #print(111)
        if  blobs:
            print(111)
            for b in blobs:
                max_blob = find_max(blobs)
                if max_blob[2]*max_blob[3]>1500  :
                    area=max_blob[2]*max_blob[3]
                    img.draw_rectangle(max_blob[0:4])
                    #print(max_blob[5])
                    if 70<max_blob[5]<90 :
                        print(max_blob[2])
                        if  max_blob[2]>70:
                            delay1()
                            print(1)
                            t=t+1

                        else:
                            print(4)
                            delay4()
                    elif max_blob[5]<71 :
                        print(2)
                        delay2()
                    elif max_blob[5]>91:
                        print(3)
                        delay3()

    if b==2 :
        print(666)
        blobs = img.find_blobs([green_threshold])

        if blobs:
            for b in blobs:
                max_blob = find_max(blobs)
                if max_blob[2]*max_blob[3]>1500  :
                    print(5)
                    delay5()
                    t=t+1




             #print(5)

             #xdelay5()
    if b==3 :
        print(1)

[kidswong999]

你的代码里，
a是什么用处，b是什么用处，t是什么用处？