在前一小节中介绍了点亮第一个LED灯，这里我们准备进阶尝试下，输出第一段PWM波形。（PWM也就是脉宽调制，一种可调占空比的技术，得到的效果就是：如果用示波器测量引脚会发现有方波输出，而且高电平、低电平的时间是可调的。）

这里爪爪熊准备写成一个golang的库，并开源到github上，后续更新将直接更新到github中，如果你有兴趣可以和我联系。 github.com/dpawsbear/bear_rpi_go

我在很多的教程中都看到说树莓派的PWM（硬件）只有一个GPIO能够输出，就是 GPIO1 。这可是不小的打击，因为我想使用至少四个 PWM ，还是不死心，想通过硬件手册上找寻蛛丝马迹，看看究竟怎么回事。

手册上找寻东西稍等下讲述，这里先提供一种方法测试 树莓派3B 的 PWM 方法：用指令控制硬件PWM。

这里通过指令的方式掌握了基本的pwm设置技巧，决定去翻一下手册看看到底PWM怎么回事，这里因为没有 BCM2837 的手册，根据之前文章引用官网所说， BCM2835 和 BCM2837 应该是一样的。这里我们直接翻阅 BCM2835 的手册，直接找到 PWM 章节。找到了如下图：

图中可以看到在博通的命名规则中 GPIO 12、13、18、19、40、41、45、52、53 均可以作为PWM输出。但是只有两路PWM0 PWM1。根据我之前所学知识，不出意外应该是PWM0 和 PWM1可以输出不一样的占空比，但是频率应该是一样的。因为没有示波器，暂时不好测试。先找到下面对应图：

根据以上两个图对比可以发现如下规律：

对照上面的表可以看出从 BCM2837 中印出来的能够使用在PWM上的就这几个了。

为了验证个人猜想是否正确，这里先直接使用指令的模式，模拟配置下是否能够正常输出。

通过上面一系列指令模拟发现，（GPIO1、GPIO26）、（GPIO23、GPIO24）是绑定在一起的，调节任意一个，另外一个也会发生变化。也即是PWM0、PWM1虽然输出了两路，可以理解成两路其实都是连在一个输出口上。这里由于没有示波器或者逻辑分析仪这类设备（仅有一个LED灯），所以测试很简陋，下一步是使用示波器这类东西对频率以及信号稳定性进行下测试。

小节：树莓派具有四路硬件输出PWM能力，但是四路中只能输出两个独立（占空比独立）的PWM，同时四路输出的频率均是恒定的。

上面大概了解清楚了树莓派3B的PWM结构，接下来就是探究如何使用Go语言进行设置。

因为拿到了手册，这里我想直接操作寄存器的方式进行设置，也是顺便学习下Go语言处理寄存器的过程。首先需要拿到pwm 系列寄存器的基地址，但是翻了一圈手册，发现只有偏移，没有找到基地址。

经过了一段时间的努力后，决定写一个 树莓派3B golang包开源放在github上，只需要写相关程序进行调用就可以了，以下是相关demo（pwm）（在GPIO.12 上输出PWM波，放上LED灯会有呼吸灯的效果，具体多少频率还没有进行测试）

以下是demo(pwm) 源码

微笑，是一种快乐微笑，是一种宽容微笑，是一种鼓励微笑，是一种幸福微笑，是最美的语言。下面是我整理了关于微笑的英语演讲稿4篇，供你参考。

关于微笑的英语演讲稿篇一

What is a smile? Some people say that the expression is the heart. I think that smile is a heart, is a strong It is a detached charmsmile is a grace, it has a warm and friendly, with acceptance and caring, with tolerance and open-minded with a relaxed and optimistic. Therefore, in working and living in a smile treat everyone around them has become my greatest wish. I smiled through every day.

Every day, I smile, I love the education of students. Early in the morning, accompanied by sun, we are ushering in a group of group of students, they have lovely, and some naughty naughty, some clever, some wood satisfied, ... ..., no matter who, no matter what he is from the family, No matter how his performance, I smiled and treat each of them.

Mischievous and occasionally also to blame, because of deterioration and while the loss due to discipline, but the office really does not keep ideas and personal considerations, the children will really be you, bit by bit to see their progress, you will more to bloom broad smiles on their faces.

Normal years, no matter what kind of class, as a teacher, guides the efforts of the children's mental and physical immersion in between the lines, so that high-spirited children from the passion straightforward, and so it goes, teachers and students do not stress and worry, so naturally, such a statement to the words to, so that the soul of the teachers and students mingled with the class as What is Education?

His seventeen years of education told me that education is a dynamic process of human spiritual encounter and dialogue. Education is looking forward to that education is in hand, education is the clarity, education is exciting, full of education with regards to the truth, education filled with smiling faces. The face of my students, I would like to smile every day.

Every day, I smile, to live together with my colleagues. People encounter is a margin of its own. Moreover, today, we have a common cause to come together, how can we not smile to cherish? Smile is the一泓spring water from the bottom of my heart, the soul of a tacit understanding friends, and strangers is to shorten the distance.

In November, I bid farewell to each other overnight partner, leaving the plants in the chest clear Xinzhuang Town primary school, went to a new collective --- a small aircraft to China. Lonely? Regret it?

When friends heard of the sorry and asked with concern, I always smile to tell you: all could hang good! School teachers and soon familiar, it's a sincere heart to the smiling face of a sincere life, in the face of work: Every day, we smiled and talked about the cause of the school, the school's development, all other schoolsa smile on the shuttle classrooms, inter-office, even though every day seems to have endless things busy, but its music also fills the air with warmth! I am happy, I smile.

Every day, I smile to face itself. I think that there is no heart murmur smile flow, there will be no free and easy life. ,

Functions, regardless of how high or how inconspicuous impressive, I do not have the time ecstasy, nor dismissive of secretly laughing, I smiled frankly accepted the blessing of his companions.

I know that school is my lucky love, duty and destiny of the appointment is lucky, I have to smile thanks to all! Difficulty comes, I have discouraged, but also thought of retreat, but in the end I was the courage to meet the challenges of a smile, because I believe that with a smile the face of suffering, then tomorrow, if you will like the bright smile today. Nevertheless, every day, every day, I also can not own them smile?

Teachers with a sincere smile treatment of students, to treat themselves, to treat everyone around you, we will have a life unmatched beauty and free and easy. Let us hope that smiled torch, go together like a glorious tomorrow, let us smile, the life of a brilliant show shine. Dear teachers, please let a smile every day!

关于微笑的英语演讲稿篇二：微笑是一种亲切

There is a kindness called smile Good afternoon, ladies and gentlemen!

Today I’d like to share my personal experience of happiness and bitterness of being an English teacher. I remember, five years ago, when I stood at the teacher’s desk for the first time, maybe because I was too young, maybe because I was too inexperienced, the students in my class paid no attention to me, didn’t behave themselves at all. I felt ashamed and helpless.

In order to save my face, I just criticized the students seriously whenever they talked in class or even moved a little. I thought sooner or later, they would listen to me.

Yes, I could control the class now, but the students and the atmosphere became strange. No, they were not listening to me. It was too quiet. The breathless silence urged me to consider the way I was teaching.

Then 1 August 2007, I got the chance to study the New Course of English. Until then could I realized that it was my frozen eyes that make the students flinch, it was my stiff face that trod out the enthusiasm in the children’s hearts. How to stimulate my class and show my warmth, so that they can enjoy their study in English? I had a deep thought.

It’s smile. There is a kindness called smile. It is the most beautiful language in the world. It can make distance no distance. “Just awake the students with a smiling face!”I said to myself. The next day, when I stood on the stage with a smiling face, when I asked the questions with a smile, when I encouraged the children in a friendly way, the students were just shocked!

But I could find there was more happiness and excitement in their eyes!

Gradually, they got used to it, and participated in my teaching. As I predicted, that class became a lovely one. I was moved, and said“Thank you for listening, boys and girls!”

In the following days, I keep on working even harder. I prepare my lessons carefully. I use Flash, pictures, riddles, and interesting stories to make great efforts to help the students to learn more. But I will never forget one thing: smile, give them a smile, to give them strength, to let them feel happy, to make them confident. The children do enjoy the English lesson now, when they tell me the answers in great excitement, I can feel their gladness, and my smile is more sincerely than ever!

There is kindness called smile. From the children’s yearning eyes, I understand, it is smile that makes my students and I get closer, it is smile that fills the kindness to my English class, it is smile that shapes me popular English teacher finally. That’s all. Thank you very much!

关于微笑的英语演讲稿篇三：The power of a smile

Smile, and sometimes can be a life to retain power. "To retain the life of laughter," tells the story of a place in the true story of the war years, in the story, a huge smile to show her magic.

War, a number of German soldiers found guilty of a terrible mistake had been closed to general, including one soldier in particular would like to go out alive, but this possibility is too remote. He was informed of his life in the death of the ultimatum had been issued - and three months would be shot, so he does not pin any hope on the survival of the. Two weeks later, he calmed down.

He visited every day to face the smiling general, the generals began to ignore him, then, he has a little goodwill, and began to talk to him ... ... three months after the date on the blink of an eye later, shot By the time this is a very strange shot: General cite shot on the left hand, right hand to give back to the team that can be a continuation of the war.

His turn, he closed his eyes, waiting for death to come, this time, his generals to see, he slowly raised his right hand ... ...

This is the life-saving force, which is hard to imagine the magic! Every day to a general apology to smile, even from its own bottom line back to the original point of death, this not the great power of a smile?

If we are able to smile in the face of every person and every thing, the success or failure of honor in the face with a smile, a smile in the face of all with a smile of genuine spiritual insights better life, it would be very happy and well-being.

Jan-mouth, will be able to draw a beautiful arc, which is how simple things! However, we do every day to add a smile to my soul? Did not - did not test test, simply Poguanposhuaijob search is unsuccessful, they feel depressedto buy lottery tickets with the first prize was only a figure on the stomp beat their chests ... ...

Strictly speaking, these trivial little too! But sometimes we do these things to worry all day, affecting many of the stem.

Smile is a force used to be a smile, a smile used to the things people will not be led by the nose, facial expression is not just a smile or a state of mind, it should be a smile from the heart. The story of the soldiers that if only the blunt expression, that the general will be more than just a pleasing.

So smile is a positive state of mind, you have a smile on other people, other people will also answer your smile.

Smile is in the hearts of the Yi Shuguang, the hearts of bright, full of hope. Smile is embedded in the heart of love, the magic of love. In the face of your life with a smile! We find that the world is so beautiful.

关于微笑的英语演讲稿篇四：Smile and the World Smiles With You

Good morning, ladies and gentlemen. Today I am very happy to be here to share with you some of my thoughts on the topic of “A Word has that Change the World——Smile and the World Smiles With You “. First, please look at my face. Do you know what I’m doing?

Yes, quite right, I’m smiling. I like smiling, because it makes me more confident and more popular. Don’t you think it important? Can you imagine a world without smiles? Can you bear seeing sad faces here and there? What a gloomy world it would without smiles!

Smile is so important of the worldit also can change the world! Smile and the world smiles with you!

Do you still remember the smiles from someone in your mind? What’s your feeling about that? The majority of people are trying to pursue happiness through their lifetime, but what is the root of happiness? I take the strong position that one of the secrets is smile. Smile makes the world go around.

It’s easier to make new friends through charming and friendly smiles. Smile always creates a good impression. Maybe we cannot remember someone’s name after meeting each other for the first timehowever, his 1

or her smile impressed us. But people sometimes overlook the importance of smiling since it is so simple. It seems that people are always in such a hurry for their own business that they complain a lot about the lack of happiness in life and some people even want to be Harry Porter to learn the magic spell of happiness.

Ladies and gentlemen, every one of us want to know exactly well what the spell actually is and the spell is can change the world. What is it? so simple and just at hand. That’s smile.

Smile is such a magic spell. It is a kind of emotional contact. It makes strangers becomes friends. It makes parents and children understand each other better and it makes the love between lovers deeper.

Smile is such a magic spell. It’s also a kind of encouragement. It makes people feel warm in ice and snow. It gives thirsty people power to walk on in a dessert. It makes cowards become brave and it makes people see hope in desperate situations.

So please remember smile make your life brighter. Smile and the world smiles with you. Every time you smile you give yourself a perfect chance to enjoy life. Every time you smile, you bring the brilliant sunshine to the whole world around you as well as to yourself.

A smile is the common language of the world, is the perfect way to communicate. Smile to the world's stability and peace is hard to imagine that role. A smile can change the world , can change the way we live and attitude.

So please smile, it will not only make your life happiness, will let others feel happy, still can let the whole world is filled with the taste of happiness!!!!!

My speech is over, thank you very much!

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