树莓派如何实现超声波车牌识别系统

这篇文章主要介绍树莓派如何实现超声波车牌识别系统，文中介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们一定要看完！

树莓派车牌识别系统

本系统使用树莓派4B

#!/usr/bin/env python# -*- coding: utf-8 -*-from luma.core.interface.serial import i2c, spifrom luma.core.render import canvasfrom luma.oled.device import ssd1306, ssd1325, ssd1331, sh2106from luma.core.virtual import terminalimport osimport timefrom PIL import ImageFontfrom aip import AipOcrfrom picamera import PiCamerafrom time import sleep#导入 GPIO库import RPi.GPIO as GPIOimport time  #设置 GPIO 模式为 BCMGPIO.setmode(GPIO.BCM)  #定义 GPIO 引脚GPIO_TRIGGER = 27GPIO_ECHO = 17  #设置 GPIO 的工作方式 (IN / OUT)GPIO.setwarnings(False)GPIO.setup(GPIO_TRIGGER, GPIO.OUT)GPIO.setup(GPIO_ECHO, GPIO.IN) serial = i2c(port=1, address=0x3C)device = sh2106(serial)APP_ID = 'XXX'API_KEY = 'YYY'SECRET_KEY = 'ZZZ'client = AipOcr(APP_ID, API_KEY, SECRET_KEY)def make_font(name, size):    font_path = os.path.abspath(os.path.join(        os.path.dirname(__file__), 'fonts', name))    return ImageFont.truetype(font_path, size, encoding="utf-8")font = make_font("/home/pi/Python/1602/msyh.ttc", 20)def distance():    # 发送高电平信号到 Trig 引脚    GPIO.output(GPIO_TRIGGER, True)      # 持续 10 us     time.sleep(0.00001)    GPIO.output(GPIO_TRIGGER, False)      start_time = time.time()    stop_time = time.time()      # 记录发送超声波的时刻1    while GPIO.input(GPIO_ECHO) == 0:        start_time = time.time()      # 记录接收到返回超声波的时刻2    while GPIO.input(GPIO_ECHO) == 1:        stop_time = time.time()      # 计算超声波的往返时间 = 时刻2 - 时刻1    time_elapsed = stop_time - start_time    # 声波的速度为 343m/s， 转化为 34300cm/s。    distance = (time_elapsed * 34300) / 2    print("距离 = {:.2f} cm".format(distance))      return distancedef i2c_12864_print(x,y,text):    with canvas(device) as draw:        draw.text((x, y), text, fill="white", font=font)        def get_file_content(filePath):    with open(filePath, 'rb') as fp:        return fp.read()    while True:        print("测量长度")    csblength = distance()    if csblength < 200:        print("程序开始，拍摄照片")        camera = PiCamera()        camera.resolution = (1024, 768)        camera.start_preview()        camera.capture('/home/pi/Python/1602/image.jpg')        camera.stop_preview()        print("拍摄结束")                    image = get_file_content('image.jpg')                 result = client.licensePlate(image);        print(result);        carNumber = result["words_result"]["number"]                 i2c_12864_print(0,0,carNumber)        break    sleep(1)

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