import sensor, image, time
from pyb import UART
import ustruct
#sensor.set_auto_exposure(False)
state="now"
last_state="once"
flag=0
code=0
green_threshold = (30, 71, -42, 5, -17, 28)  #绿色阈值
yellow_threshold = (66, 100, -30, 19, -6, 50)  #黄色阈值
thresholds = [yellow_threshold, green_threshold]

sensor.reset()
sensor.set_pixformat(sensor.RGB565)
sensor.set_framesize(sensor.QVGA)
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

clock = time.clock()

uart = UART(3,9600)   #定义串口3变量
uart.init(9600, bits=8, parity=None, stop=1) # init with given parameters

def find_max(blobs, min_size=0):
    if not blobs:  # 处理空列表情况
        return None
    
    max_blob = None
    max_size = 10000# 初始化为最小像素数量

    for blob in blobs:
        size = blob.pixels()  # 获取像素数量
        if size > max_size:  # 增加对最小像素数量的判断
            max_blob = blob
            max_size = size
    return max_blob

def send_data_packet(code):
    print(f"已发送类型{code}")
    uart.write(str(code))#串口发送

while(True):
    img = sensor.snapshot()
    blobs = img.find_blobs(thresholds);
    cx=0;cy=0;
    if blobs:
        max_b = find_max(blobs)
        
        if max_b:
            img.draw_rectangle(max_b[0:4]) #用矩形标记出目标颜色区域
            img.draw_cross(max_b[5], max_b[6]) #在目标颜色区域的中心画十字形标记
            cx=max_b[5];
            cy=max_b[6];
            cw=max_b[2];
            ch=max_b[3];
            code=max_b[8];
            state=str(code)
            
            if last_state!=state:
                send_data_packet(code)
                
            last_state=state
        else:
            istate="now"
            last_state="once"