89S52单片机实现40KHZ超声波探头距离测量

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该资源的标题为“CJ.rar_cj_超声波_超声波探头”,说明文件中包含的内容与超声波技术相关,尤其是超声波探头的应用。描述提到“超声波测量距离的源代码,使用用89S52和40KHZ产生波探头”,表明资源内提供了使用89S52单片机以及40kHz频率的超声波探头进行距离测量的源代码示例。标签为“cj 超声波 超声波探头”,进一步确认了资源的主题内容。而文件名称列表中的“CJ.asm”表明源代码文件使用汇编语言编写,是与硬件紧密相关的底层代码。" 知识点详细说明: 1. 超声波技术基础: 超声波技术是利用频率高于20kHz的声波进行各种测量和操作的一种技术。超声波在介质中传播时,能反射、折射、衰减和散射,这种特性使其在距离测量、成像、清洁等领域有广泛应用。 2. 超声波探头及其应用: 超声波探头是产生和接收超声波信号的装置,它将电能转换为声能,或者将声能转换为电能。在测量距离的应用中,超声波探头通常用于发射超声波脉冲,并接收目标物体反射回来的超声波信号,通过计算发射和接收信号的时间差来确定距离。 3. 超声波测量距离原理: 超声波测量距离通常基于时间行程法,即超声波探头发射超声波脉冲后,测量声波从探头传到目标物体并反射回来的总时间。已知声速在空气中的传播速度大约是340m/s,在特定条件下可以视为恒定值。通过计算时间差和声速,可以计算出距离。 4. 89S52单片机: 89S52是一种8位微控制器,属于51系列单片机之一。其内部集成了8位CPU、一定量的RAM、ROM、I/O接口、定时器/计数器、串行口等基本功能模块。由于其简单、稳定、易于控制等优点,广泛用于各种嵌入式系统和测量设备中。 5. 40kHz超声波频率: 40kHz是超声波探头常用的频率之一。该频率的声波在空气中的衰减相对较小,能较远距离传输,同时波长适中,适合进行距离和尺寸的精确测量。 6. 汇编语言编程: 汇编语言是一种低级编程语言,它与机器代码非常接近,可以实现硬件级的精确控制。在嵌入式系统开发中,尤其是在对资源和性能有严格要求的场合,汇编语言的使用可以带来更好的控制精度和程序运行效率。 7. 超声波探头的种类: 超声波探头主要分为压电式、磁致伸缩式和电磁式等类型。压电式探头是利用压电材料在电场作用下产生机械变形的原理来发射和接收超声波,其结构简单、成本低廉、可靠性高,是应用最为广泛的类型之一。 结合以上知识点,我们可以得知,本资源为使用汇编语言编写的超声波距离测量程序,其利用89S52单片机作为控制核心,通过40kHz的压电式超声波探头来发射和接收超声波,实现对距离的精确测量。该资源适用于学习和研究超声波测量技术、嵌入式系统开发等领域的IT专业人士。

select csr.school_year 学年,csr.name 学期,cs.name 姓名,cs.code 学号,cs.grade 年级,cd.name 学院,cm.name 专业,ca.name 行政班,cj.lesson_no 课程号,tc.code 课程代码,tc.name 课程名称, listagg(ct.name,',') within group(order by ct.name) 授课教师, tc.credits 学分,cj.score_text 分数,cj.gp 绩点,xc.name 课程类别,xc.code 课程类别代码,hc.name 修读类别,xs.name 学生类别,pscj.score_text 平时成绩,qzcj.score_text 期中成绩, sycj.score_text 实验成绩,qmcj.score_text 期末成绩,zpcj.score_text 总评成绩,bkcj.score_text 补考成绩 from t_course_grades cj left join c_students cs on cs.id = cj.std_id left join c_semesters csr on csr.id = cj.semester_id left join t_courses tc on tc.id = cj.course_id left join c_departments cd on cd.id = cs.department_id left join c_majors cm on cm.id = cs.major_id left join c_adminclasses ca on ca.id = cs.adminclass_id left join xb_course_types xc on xc.id = cj.course_type_id left join hb_course_take_types hc on hc.id = cj.course_take_type_id left join xb_std_types xs on xs.id = cs.type_id left join t_lessons_teachers tlt on tlt.lesson_id=cj.lesson_id left join c_teachers ct on ct.id = tlt.teacher_id left join t_exam_grades bkcj on cj.id = bkcj.course_grade_id and bkcj.grade_type_id=4 left join t_exam_grades pscj on cj.id = pscj.course_grade_id and pscj.grade_type_id=3 left join t_exam_grades qzcj on cj.id = qzcj.course_grade_id and qzcj.grade_type_id=1 left join t_exam_grades zpcj on cj.id = zpcj.course_grade_id and zpcj.grade_type_id=7 left join t_exam_grades qmcj on cj.id = qmcj.course_grade_id and qmcj.grade_type_id=2 left join t_exam_grades sycj on cj.id = sycj.course_grade_id and sycj.grade_type_id=8 where cj.semester_id='243' and cs.code='21403186' order by cs.code

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springboot+MyBatis连接MySql数据库遇到问题:### Error querying database. Cause: com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure The last packet successfully received from the server was 11,751 milliseconds ago. The last packet sent successfully to the server was 11,858 milliseconds ago. ### The error may exist in file [/app/tomcat/webapps/project/WEB-INF/classes/mapper/PersonWeekMapper.xml] ### The error may involve com.xmsme.mapper.PersonWeekMapper.selectPersonWeekList-Inline ### The error occurred while setting parameters ### SQL: SELECT count(0) FROM (SELECT WEEK.id, WEEK.sub_time, WEEK.need_thing, WEEK.plan_content, WEEK.target_content, WEEK.sub_time AS update_time, WEEK.create_time, WEEK.week_start, WEEK.user_id, WEEK.week_end, readInfo.id AS readId, readInfo.read_status AS readStatus, updateor.nick_name FROM t_person_weekly AS WEEK LEFT JOIN sys_user sUser ON sUser.user_id = WEEK.user_id LEFT JOIN t_read_info readInfo ON readInfo.business_id = WEEK.id AND readInfo.read_type = 'PER' LEFT JOIN sys_user updateor ON updateor.user_id = WEEK.update_by LEFT JOIN sys_user_role uRole ON uRole.user_id = WEEK.update_by LEFT JOIN sys_user_post uPost ON uPost.user_id = WEEK.user_id LEFT JOIN t_project_person person ON person.user_id = WEEK.user_id LEFT JOIN t_project_person Pperson ON Pperson.project_id = person.project_id WHERE 1 = 1 AND WEEK.is_del = 0 AND WEEK.draft = 'N' AND Pperson.user_id = ? GROUP BY WEEK.id) table_count ### Cause: com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure The last packet successfully received from the server was 11,751 milliseconds ago. The last packet sent successfully to the server was 11,858 milliseconds ago. ; Communications link failure The last packet successfully received from the server was 11,751 milliseconds ago. The last packet sent successfully to the server was 11,858 milliseconds ago.; nested exception is com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure The last packet successfully received from the server was 11,751 milliseconds ago. The last packet sent successfully to the server was 11,858 milliseconds ago.

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