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单片机的 P34、P35、P36、P37口分别接LED1、LED2、LED3、LED4, 输出低电平点亮LED灯,P20、P21口分别接按键K1、K2,按键按下输入单片机为低电平,程序如下: #include<reg52.h> sbit K1=P2^0; sbit K2=P2^1; bit flag_add=0,flag_rdu=0; void Delay10ms(unsigned char i) //@11.0592MHz { unsigned char j; i =i* 18;j = 235; do{ while (--j); } while (--i); } void main() { char i=0; while(1) { if(K1==0) { flag_add=1;flag_rdu=0; } if(K2==0) { flag_add=0;flag_rdu=1; } if(flag_add)i++; if(flag_rdu)i--; Delay10ms(10); P3=~(i<<4); if(i>=16)i=0; if(i<0)i=15; }>

A.按下K1后,4个LED组成0-15的自动减法计数器;

B.按下K1后,4个LED组成0-15的自动加法计数器;

C.按下K2后,4个LED组成0-15的自动减法计数器;

D.在无按键按下的情况下,4个灯全灭。

提问人:网友lewisbottle 发布时间:2022-01-07
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更多“单片机的 P34、P35、P36、P37口分别接LED1、L…”相关的问题
第1题
单片机的P34、P35、 P36 、P37 口分别接LED1、LED2、LED3、LED4,输出低电平点亮LED灯, P32口接按键K1,按键按下时单片机输入低电平,程序如下: #include "reg52.h" sbit P32=P3^2; void main() { case 0: P3 = 0xef; break; case 1: P3 = 0xdf; break; case 2:
A.采用外部中断的方式实现4个LED的轮流亮灭;

B.执行EX0=1;的功能是使能外部中断 0 ;

C.采用定时中断的方式实现4个LED的轮流亮灭;

D.执行IT0=1;的功能是采用外部中断 0 边 沿触发方式。

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第2题
已知P1端口从P1.0~P1.7依次接有八个发光二极管VD0~VD7,二极管阳极接+5V,阴极通过限流电阻分别接单片机,若要同时点亮VD1、VD4,其它灯不亮,则P1应该赋值为?
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第3题
若P1_6和P1_7分别接到LED1和LED2上,低电平是可以点亮相应的LED灯。S1按键连接在P0_0端口,按下S1键时P0_0为低电平。要求编程实现,按下S1时LED1和LED2可以交替点亮。
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第4题
设计编写一个程序,用查询方式来读取一个按键状态,并控制一个 LED 的亮和灭。即按一下灯亮、再按一下灯灭,可重复操作,要求每次操作执行可靠。
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第5题
如果要求点亮LED0、LED2,P1=()
A.0x05

B.0x3f

C.0xfa

D.0x5f

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第6题
8个发光二极管的阴极接在单片机的P1口上,阳极经过300Ω的电阻接到+5V电源上,要使P1.0和P1.1所接的二极管发光,P1口输出的十六进制信息应该为( )。

A、0xfe

B、0xfc

C、0xcf

D、0xef

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第7题
以下程序为一个用状态机构成的交通灯,其中LEDR_H、LEDG_H、LEDY_H,为一个方向的红、绿、黄灯,LEDR_V、LEDG_V、LEDY_V,为另一个方向的红、绿、黄灯,Clk为频率为1Hz的时钟,则以下说法中正确的是()。reg[1:0]state;always@(posedgeClkornegedgeRst)beginif(!Rst)beginLedR_H<=0;LedG_H<=0;LedR_V<=0;LedG_V<=0;LedY_H<=0;LedY_V<=0;endelsebegincase(state)S1:beginif(Cnt35<=30)beginLedR_H<=1;LedG_H<=0;LedY_H<=0;LedR_V<=0;LedG_V<=1;LedY_V<=0;endelsestate<=S3;endS2:beginif(Cnt35<=30)beginLedR_H<=0;LedG_H<=1;LedR_V<=1;LedG_V<=0;LedY_H<=0;LedY_V<=0;endelsestate<=S4;endS3:beginif(Cnt35>=30)beginLedR_H<=1;LedG_H<=0;LedR_V<=0;LedG_V<=0;LedY_H<=0;LedY_V<=1;endelsestate<=S2;endS4:beginif(Cnt35>=30)beginLedR_H<=0;LedG_H<=0;LedR_V<=1;LedG_V<=0;LedY_H<=1;LedY_V<=0;endelsestate<=S1;endDefault:beginLedR_H<=0;LedG_H<=gai0;LedR_V<=0;LedG_V<=0;LedY_H<=0;LedY_V<=0;endendcaseendend

A、该状态机是moore型

B、黄灯每次亮5秒

C、红灯每次亮35秒

D、绿灯每次亮35秒

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第8题
若某一LED的正向工作电流为350mA,正向工作电压为7V,光通量为15lm,其发光效率为( )

A、2.1%

B、2.1lm/W

C、6.1%

D、6.1lm/W

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第9题

1 An accidental discovery announced recently has taken LED lighting to a new level, suggesting it could soon offer a cheaper, longer-lasting alternative to the traditional light bulb. The breakthrough adds to a growing trend that is likely to eventually make Thomas Edison&39;s bright invention obsolete. LEDs are already used in traffic lights, flashlights, and architectural lighting. They are flexible and operate less expensively than traditional lighting.

2 Michael Bowers, a graduate student2 at Vanderbilt University, was just trying to make really small quantum dots, which are crystals generally only a few nanometers big. Quantum dots contain anywhere from 100 to 1,000 electrons. They&39;re easily excited bundles of energy, and the smaller they are, the more excited they get. Each dot in Bowers&39; particular batch was exceptionally small, containing only 33 or 34 pairs of atoms.

3 When you shine a light on quantum dots or apply electricity to them, they react by producing their own light, normally a bright, vibrant color. But when Bowers shined a laser on his batch of dots, something unexpected happened. He was surprised when a white glow covered the table. The quantum dots were supposed to emit blue light, but instead they were giving off a beautiful white glow.

4 Then Bowers and another student got the idea to stir the dots into polyurethane and coat a blue LED light bulb with the mix. The lumpy bulb wasn&39;t pretty, but it produced white light similar to a regular light bulb.

5 LEDs produce twice as much light as a regular 60 watt bulb and burn for over 50,000 hours. The Department of Energy estimates LED lighting could reduce U. S. energy consumption for lighting by 29 percent by 2025. LEDs don&39;t emit heat, so they&39;re also more energy efficient. And they&39;re much harder to break.

6 Quantum dot mixtures could be painted on just about anything and electrically excited to produce a rainbow of colors, including white. The main light source of the future will almost surely not be a bulb. It might be a table, a wall, or even a fork.

Paragraph 1 ______

A LED Lighting Is Not MatureB LED Lighting Will Replace Traditional LightingC Almost Everything Could Be the Main Light Source in the FutureD LED Lighting Has Many AdvantagesE Bowers Made an Unexpected DiscoveryF LED Light Bulbs Look Lumpy

Paragraph 3 ______

A LED Lighting Is Not MatureB LED Lighting Will Replace Traditional LightingC Almost Everything Could Be the Main Light Source in the FutureD LED Lighting Has Many AdvantagesE Bowers Made an Unexpected DiscoveryF LED Light Bulbs Look Lumpy

Paragraph 5 ______

A LED Lighting Is Not MatureB LED Lighting Will Replace Traditional LightingC Almost Everything Could Be the Main Light Source in the FutureD LED Lighting Has Many AdvantagesE Bowers Made an Unexpected DiscoveryF LED Light Bulbs Look Lumpy

Paragraph 6 ______

A LED Lighting Is Not MatureB LED Lighting Will Replace Traditional LightingC Almost Everything Could Be the Main Light Source in the FutureD LED Lighting Has Many AdvantagesE Bowers Made an Unexpected DiscoveryF LED Light Bulbs Look Lumpy

Unlike traditional lighting, LEDs do not give out heat so ______.

A traditional lighting is less durable and dearerB a laser excited the quantum dotsC America adopted LEDsD graduate students work hardE quantum dot mixtures are magicF it is more efficient

Edison&39;s bright invention is likely to be outdated because ______.

A traditional lighting is less durable and dearerB a laser excited the quantum dotsC America adopted LEDsD graduate students work hardE quantum dot mixtures are magicF it is more efficient

Something unexpected happened during Bower&39;s experiment when ______.

A traditional lighting is less durable and dearerB a laser excited the quantum dotsC America adopted LEDsD graduate students work hardE quantum dot mixtures are magicF it is more efficient

Over one quarter of energy consumption for lighting could be saved by 2025 if ______.

A traditional lighting is less durable and dearerB a laser excited the quantum dotsC America adopted LEDsD graduate students work hardE quantum dot mixtures are magicF it is more efficient

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第10题
试说明发光二极管的结构和工作原理。发光二极管的特征参数和极限参数有哪些?
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