# 1.2. First experiment--light LED

Source: Internet
Author: User

1.2. First experiment--light LED

Pre-Knowledge:

(1) Bits, bytes, io ports, io port

``  字节是内存管理的最小单位，一个字节是八位，每一位可以存放一个二进制位（0或者1）。一个IO端口包括一组IO口，一般一组是八个，一个端口就是一组IO引脚。一个IO口对应一个二进制位，一个IO端口对应一个字节。``

A hexadecimal bit equals four bits, for example, 0xFF corresponds to a binary is 1111 1111

Experimental Purpose: Eight LED lights are lit

Analysis of the experimental process:

(1) Eight LEDs are controlled by eight-bit bits, bits is 1 o'clock LED light, bits is 0 o'clock LED lights out
(2) Eight LEDs are lit separately, with no effect on each other
(3) Because 1 control LED is bright, so want eight LED lights full light, the corresponding binary number is 1111 1111, converted to 16 is 0xFF
(4) If you want to let eight led interval light, the corresponding binary number is 1010 1010, converted to 16 binary is 0xAA
(5) An IO port control eight bits, each one to control one led, in this microcontroller reference P0 port

Experimental phenomena:

When P0=0xff, eight led all bright, when p0=0x0, eight led all out, when P0=0XAA, eight led interval light off.

Experiment Code:

``#include<reg51.h>void main(void)    {        //通过P0这个IO端口控制八颗LED灯        P0=0xff;//点亮八颗LED        P0=0x0f;//点亮四颗LED        P0=0xAA;//隔一颗亮一颗 二进制数为10101010    }``

Experiment Summary:
(1) 1 corresponds to High level, the P0 port output high power, generate a voltage difference, so that led bright. The opposite 0 corresponds to the low level.
(2) binary and hexadecimal conversions need to be enhanced.

1.2. First experiment--light LED

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