DIY ultra detailed tutorial on making oscilloscope: (1) I'm not trying to make an oscilloscope

Tell a story ：

This September , The beginning of a new semester , Few classes .

I'm a busy person , Such a day is hard , Want to go to the electronic market , But the school is 30 away from the city More than... Kilometers , Finally bored to the weekend .

As usual , Shopping in the electronic market is all about looking here and there , I like to ask when I meet someone I haven't seen , Years of habits cannot be changed ……

On a counter “ Deal with it at a low price LCD modular ” Brand , For a poor student like me , Price is often the main consideration . I walked straight over , The boss said these low-cost screens are brand new , Just no information , the It can only be handled at a low price , So I coveted a small cheap flower 30 I bought a piece for yuan 128*64 Dot matrix screen with high resolution . like People who covet small and cheap things often suffer losses in the end , Finally, I really “ A disadvantage ” 了 , Just because of this screen , It cost me nearly 300 I bought one piece 320*240 Screen of .

After returning to school, go online to find its information , Everything comes to him who waits , I found it . We know from the information that this LCD does not have a font , This makes me a little disappointed , But it only took 30 Yuan will be fine . Compile according to the data Write a program to let it display some simple graphics , But to make it display graphics or characters, you have to make dots of what you want to display Array data is stored in the array , It's a waste of poor resources in SCM ！ Dot matrix screen without font is chicken ribs ！

Is wandering “ There is no meat to eat , It's delicious to abandon ” When , A sudden flash of inspiration , Why not use it to show some real time What about your graphics ？ What does it show ？ The bright oscilloscope inspired me , Let it show the waveform ！ Just right for me AVR SCM with AD converter , Do as you say , Busy all afternoon , The waveform is displayed at night . This is not Is it a basic digital oscilloscope ？ chart 1 Sum graph 2 That was the time “ Precious photos ”, Because that circuit will be in the future Has been dismantled by me in the experiment of . I bought these two photos LCD The next night of the screen .

The success of the first step , It strengthens my belief in making digital oscilloscope . People always have something to pursue , So I want to improve it ！ In fact, this is no different from “ Buy a horse for having a saddle ”, But that's not always bad .

I have something to do in the next week ……

The second weekend , I took out my living expenses for half a month , I spent more than 300 yuan to buy one 320*240 Liquid crystal display Screen and two pieces TLC5510, I started my journey of self-made digital oscilloscope .

I never thought about making a digital oscilloscope before , Therefore, the understanding of digital oscilloscope only stays on the basic principle and function , Deeper things are almost blank . But I believe in the knowledge of electricity , As long as you work hard, there is no I can't learn , So I began to look for information everywhere , But whether it's the library or the Internet , There is hardly a ready-made electricity Roads or examples are available for reference , In this case, we can only rely on ourselves , Draw a block diagram according to your own understanding , Step by step experiments .

At first, I used AVR The design of MCU ADC, The fastest conversion rate is 40k（ It is not required to achieve 10 Bit accuracy ）, So it can barely measure twoorthree Hertz , I'm certainly not satisfied with this performance ！ So we use the external high-speed ADC, At this time TLC5510 That comes in handy , Its maximum conversion rate is 20MSa/s, In order to achieve high-speed sampling, I Provide it with 20MHz The clock signal of ,8 Bit parallel data is directly sent to MCU , There's a problem , SCM is too slow , There is no time to read the data . Through consulting the information, I learned that the buffer of high-speed data can be used FIFO Memory , This is my first One touch FIFO Memory . The third weekend , I spent it. 40 I bought one piece for yuan 4KB The capacity of FIFO Memory IDT7204, Until now, this oscilloscope still uses this memory .FIFO The use of solves the problem that the single chip computer has no time to read Data problems , But there are still many problems left ： How to control the scanning speed 、 How to control sensitivity 、 How to control triggering ……

Too many “ how ” I don't know how to sleep well for several nights , But that's exactly what “ how ” Gave me to solve these “ how ” Power …… I like to challenge myself . Change the plan , test , debugging , Change the plan , Re experiment , Again debugging …… Finally, one by one “ how ” I solved it , Excitement made me wonder how to sleep for several nights . This is Like a country's civil war , No matter who wins or loses, it is always this country that gets hurt , But it has promoted the progress of history . I just It makes progress in finding and solving problems , Although a little hurt …… During the experiment, I got 《 radio 》 Magazines Editor Yin Fei's help , I am very grateful for his spiritual and material support ！

Finally, I made this digital oscilloscope , Also achieved my initial requirements , It can better measure 5MHz, Such performance may be worse than that of a professional oscilloscope , But it is used in audio circuit and ordinary electronic production and debugging It can still meet the requirements , Insufficient 500 I think the cost of yuan is very practical , Especially for poor students like me Child lovers .

Who is interested in self-made digital oscilloscope ？

Want to experience the feeling of excitement to insomnia ？

Come with me , We experience this excitement together ！