禁用摄像头后，帧率不变。

[3lmp]

禁用和开启摄像头，系统的输出的帧率没有改变，讲道理禁用摄像头后，帧率应该有提升才对啊。
禁用和不禁用都是24帧

未禁用时

禁用时

请在这里粘贴代码
```import sensor, image, time, math,lcd,struct
from pyb import UART
from pyb import LED
import json

def send_data_packet(x, y):
    temp = struct.pack(">bBBb",                #格式为俩个字符俩个整型
                   0xAA,                       #帧头1
                   int(x), # up sample by 4    #数据1
                   int(y), # up sample by 4    #数据2
                   0xAE)                       #帧头2
    uart.write(temp)

# Color Tracking Thresholds (Grayscale Min, Grayscale Max)
# The below grayscale threshold is set to only find extremely bright white areas.
xiaoqiu = (130, 255)
zuobiao = (140, 180)
left_roi =(65,52,459,432)

a = 0
led1 = LED(1)   #red
led2 = LED(2)   #green

sensor.reset()
sensor.set_pixformat(sensor.GRAYSCALE)
sensor.set_framesize(sensor.VGA)
sensor.skip_frames(time = 2000)
sensor.set_auto_gain(False) # must be turned off for color tracking
sensor.set_auto_whitebal(False) # must be turned off for color tracking
sensor.set_auto_exposure(False,4000)
clock = time.clock()
uart = UART(3,115200)  #串口3，波特率115200
uart.init(115200,bits=8,parity=None,stop=1)


# Only blobs that with more pixels than "pixel_threshold" and more area than "area_threshold" are
# returned by "find_blobs" below. Change "pixels_threshold" and "area_threshold" if you change the
# camera resolution. "merge=True" merges all overlapping blobs in the image.

while(True):
    clock.tick()
    led1.toggle()
    img = sensor.snapshot()
    if a==0:
       if img.find_blobs([xiaoqiu],roi=left_roi,pixels_threshold=60, area_threshold=60, merge=True)==[]:
            led1.on()#亮
            led2.off()#灭
            #send_data_packet(180,180)
            send_data_packet(clock.fps(),clock.fps())
            print(clock.fps())
       else:
           for blob in img.find_blobs([xiaoqiu],roi=left_roi,pixels_threshold=60, area_threshold=60, merge=True):
              # These values depend on the blob not being circular - otherwise they will be shaky.
              # These values are stable all the time.
              img.draw_rectangle(blob.rect(), color=200)
              img.draw_cross(blob.cx(), blob.cy(), color=0)
              send_data_packet(blob.cx(),blob.cy())
              print(blob.cx(),blob.cy())
              led2.on()
              led1.off()
              #output_str="[%d,%d]" % (blob.cx(),blob.cy())
              #uart.write(output_str+'\r\n')
              print(clock.fps())

[kidswong999]

确实不变，
我测试了，OpenMV4H7上，GRAYSCALE和VGA，无论是否禁用，都是30帧左右。
如果代码少一点只采集，大概是35帧。

[3lmp]

这个帧率那就是极限了么？按理来说禁用摄像头应该是有所提升的，是不是我哪里的配置不对啊.

[kidswong999]

@3lmp OpenMV4传输给电脑有DMA的，不是完全串行的，

使用OpenMV3测试，禁用13帧，不禁用6帧。