openmv识别特定颜色且打印坐标到串口

【核心代码】

#@Luan/2019/7
#改编跟踪识别且发送
# Pin P4 to the serial input of a serial LCD screen to see data printed
# on the serial LCD display.
import sensor, image, time, math
from pyb import UART
# Always pass UART 3 for the UART number for your OpenMV Cam.
# The second argument is the UART baud rate. For a more advanced UART control
# example see the BLE-Shield driver.
uart = UART(3, 19200, timeout_char=1000)    #串口3 波特率19200 超时时间1s

threshold_index = 0 # 0 for red, 1 for green, 2 for blue

# Color Tracking Thresholds (L Min, L Max, A Min, A Max, B Min, B Max)
# The below thresholds track in general red/green/blue things. You may wish to tune them...
thresholds = [(30, 100, 15, 127, 15, 127), # generic_red_thresholds
              (30, 100, -64, -8, -32, 32), # generic_green_thresholds
              (0, 30, 0, 64, -128, 0)]     # generic_blue_thresholds

sensor.reset()
sensor.set_pixformat(sensor.RGB565)
sensor.set_framesize(sensor.QVGA)          #320*240 Dpi
sensor.skip_frames(time = 2000)            #跳过几帧 初始化
sensor.set_auto_gain(False)                #关闭自动增益
sensor.set_auto_whitebal(False)            #关闭白平衡
clock = time.clock()

# 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()
    img = sensor.snapshot()                #拍照
    for blob in img.find_blobs([thresholds[threshold_index]], pixels_threshold=200, area_threshold=200, merge=True):
        # These values depend on the blob not being circular - otherwise they will be shaky.
        if blob.elongation() > 0.5:
            img.draw_edges(blob.min_corners(), color=(255,0,0))
            img.draw_line(blob.major_axis_line(), color=(0,255,0))
            img.draw_line(blob.minor_axis_line(), color=(0,0,255))
        # These values are stable all the time.
        img.draw_rectangle(blob.rect())     #方框
        img.draw_cross(blob.cx(), blob.cy())#中点
        # Note - the blob rotation is unique to 0-180 only.
        img.draw_keypoints([(blob.cx(), blob.cy(), int(math.degrees(blob.rotation())))], size=20)
        uart.write(json.dumps(bytearray([blob.cx(),blob.cy()])))#串口输出找到的点的坐标
        uart.write('\r\n')
    print(clock.fps())