【正文】 , can easily change the output current, thereby regulating the brightness of white light LED. PWM dimming has the advantage of being able to provide high quality white light, and the application of simple, high efficiency! For example, in a mobile phone system, using a special PWM interface can easily generate arbitrary duty cycle of the pulse signal, the signal is passed through a resistor, connected to the drive EN interface. Most manufacturers drive support PWM dimming. For Buck, Boost, BuckBoost or linear regulator to drive LED, their mon ideas are the drive circuit to control the output of light. Some applied simply to achieve the on and off function, but more application demand is to be from 0 to 100% regulates the brightness of the light, and often have very high precision. The designer has two main options: linear regulator LED current ( analog dimming ), or using the switch circuit with respect to human recognition capacity, a high enough frequency to change the average light output ( digital dimming ). The use of pulse width modulation ( PWM ) to set the cycle and duty cycle ( Figure 1 ) is probably the most simple digital dimming method, and Buck regulator topology can often provide a best performance. KEY WORDS digital pulse ,duty ,drive circuit ,linear regulator 基于單片機的 PWM 調(diào)光 III 目 錄 中文摘要 ……………………………………………………………………………………… I 英文摘要 ……………………………………………………………………………………… II 引 言 .......................................................................................................................... 1 1 單片 機應用技術簡介 ......................................................................................... 2 單片機內(nèi)部構成 ....................................................................................... 2 單片機的工作原理 .................................................................................. 2 2 PWM 調(diào)光原理簡介 ............................................................................................... 4 PWM 調(diào)光技術原理 ................................................................................... 4 脈沖寬度調(diào)節(jié) ...................................................................................... 4 PWM 對于 LED 調(diào)光的優(yōu)勢 ................................................................... 5 LED 光源的特性 ........................................................................................ 7 3 電路設計 ................................................................................................................ 8 電路設計流程圖 ....................................................................................... 8 主控元件與功能模塊介紹 .................................................................... 8 按鍵功能設計 ...................................................................................... 8 主控元件單片機 .................................................................................. 8 光源模塊 .............................................................................................11 電源的選擇與連接 .............................................................................11 其他元件工作特性 ................................................................................ 12 LED 發(fā)光二極管功能簡介 ................................................................. 12 晶振的作用與電路的連接 ................................................................ 13 4 實物裝配與調(diào)試 ................................................................................................ 16 實物裝配流程 ......................................................................................... 16 按照電路原理圖焊接組件 ................................................................ 16 元器件清單及型號 ............................................................................ 16 單片機內(nèi)部程序的編寫 ....................................................................... 16 焊接工序注意事項 ................................................................................ 16基于單片機的 PWM 調(diào)光 IV 調(diào)試完善功能 ......................................................................................... 19 結束語 ........................................................................................................................ 19 致 謝 .............................................................................................. 錯誤 !未定義書簽。設計者主要有兩個選擇：線性調(diào)節(jié) LED 電流（模擬調(diào)光），或者使用開關電路以相對于人眼識別力來說足夠高的頻率工作來改變光輸出的平均值（數(shù)字調(diào)光）。 不管用 Buck, Boost, BuckBoost還是線性調(diào)節(jié)器來驅(qū)動 LED，它們的共同思路都是用驅(qū)動電路來控制光的輸出。 PWM 調(diào)光的優(yōu)點在于能夠提供高質(zhì)量的白光，以及應用簡單，效率高！例如在手機的系統(tǒng)中，利用一個專用 PWM 接口可以簡單的產(chǎn)生任意占空比的脈沖信號，該信號通過一個電阻，連接到驅(qū)動器的 EN 接口?；趩纹瑱C的 PWM 調(diào)光 I 基于單片機的 PWM 調(diào)光燈 摘 要 PWM 調(diào)光是一種利用簡單的數(shù)字脈沖，反復開關白光 LED 驅(qū)動器的調(diào)光技術。應用者的系統(tǒng)只需要提供寬、窄不同的數(shù)字式脈沖，即可簡單地實現(xiàn)改變輸出電流，從而調(diào)節(jié)白光 LED 的亮度。多數(shù)廠商的驅(qū)動器都支持 PWM 調(diào)光。一些應用只是簡單地來實現(xiàn) “ 開 ” 和“ 關 ” 地功能，但是更多地應用需求是