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2.5. Exchanging data through a serial port

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Building Arduino robots and devices

Instituto de Física y Tecnología de Moscú

4.3 (241 calificaciones) | 29K estudiantes inscritos

For many years now, people have been improving their tools, studying the forces of nature and bringing them under control, using the energy of the nature to operate their machines. Last century is noted for the creation of machines which can operate other machines. Nowadays the creation of devices that interact with the physical world is available to anyone. Our course consists of a series of practical problems on making things that work independently: they make their own decisions, act, move, communicate with each other and people around, and control other devices. We will demonstrate how to assemble such devices and programme them using the Arduino platform as a basis. After this course, you will be able to create devices that read the data about the external world with a variety of sensors, receive and forward this data to a PC, the Internet and mobile devices, and control indexing and the movement. The creation of such devices will involve design, the study of their components, the assemblage of circuit boards, coding and diagnostics. Along with the creation of the devices themselves, you will perform visualization on a PC, create a web page that will demonstrate one of your devices, and figure out how an FDM 3D-printer is configured and how it functions. Besides those keen on robotics or looking to broaden their horizons and develop their skills, the course will also be useful to anyone facing the task of home and industrial automation, as well as to anyone engaged in industrial design, advertising and art. The course does not require any special knowledge from the participants and is open even to students of upper secondary school. Programming skills and the level of English allowing to read technical documentation would be an advantage, but this is not obligatory. The entire course is dedicated to practice, so the best way for you would be to get hold of some electronics, follow the illustrated examples and experiment on your own. The kits can be purchased here: kits.cyberphysica.ru. Taught by: Alexey Perepelkin, head of Robotics department in the Laboratory of innovative educational technologies at MIPT Taught by: Dmitry Savitsky, researcher in the Laboratory of innovative educational technologies at MIPT

Destrezas que aprenderás

Electronics, Computer Programming, Arduino, Robotics

Revisiones

4.3 (241 calificaciones)

5 stars
152 ratings
4 stars
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3 stars
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1 star
14 ratings

CH

Nov 12, 2017

A very complete and helpful course, covering many options you have with Arduino. I really enjoyed it. Thank you very much!

AC

Jan 22, 2019

Is an admired course. I can't wait to have my fingers wrapped around it. I am really excited to be on this program.

De la lección

Week 2

It’s time to learn how to receive data with the help of sensors. During Week 2, we will teach you how to read off digital and analog signals, exchange data with a computer, create more complex algorithms, and use new output devices.

2.1. Week overview1:16

2.2. First sensor1:56

2.3. Voltage divider5:19

2.4. How to read off analog signals5:30

2.5. Exchanging data through a serial port6:44

2.6. About a signal8:45

2.7. Reading off digital signals5:37

2.8. Boolean expressions and program branching16:43

2.9. New display devices: buzzer and bar graph13:12

2.10. Seven-segment display2:24

2.11. Microchips4:25

2.12. Output shift register13:21

2.13. Debugging5:37

2.14. Usage of modules6:19

2.15. Monitoring system12:01

Impartido por:

Алексей Перепелкин
Руководитель направления развития цифрового творчества
Дмитрий Савицкий
Научный сотрудник

Transcripción

Now, let's talk about how data is output through a serial port. Arduino has a standard tool for this purpose which we have already used. Let's once again, look at the AnalogReadSerial example and pay attention to this serial begin 9,600 line in the Setup section. What exactly is the serial highlighted in bold orange font? This is a so-called "object". The object, which is proposed to us by Arduino library, during our course, we won't be concentrating too much on what objects are. You can read about this in additional materials. Let's just regard it as some black box. Supposedly, we know what it can give us. In other words, we know what we can communicate to its inputs and what we can get at its output. Well, this black box is the Serial object designed, to exchange data through a serial port. Physically, this data exchange happens either via a USB port, through which your board is connected to your computer or through pins 0 and 1 simultaneously. If you look at it attentively, you will see inscriptions RX and TX. They are also destined to exchange data. When we download a sketch it is conveyed through the same lines, that's why when you assemble your device, try to use pins 0 and 1 last, because when you download your sketch and something is connected to the pins, this can prevent your device from functioning correctly. Now let's have a look at what happens with this serial object. Can you see that after the period we have the word "begin" to which the parameter 9,600 has been passed? In reality this is what's known as calling a function. What we just did. For example, with analog read or digital write during week one. When we refer to objects, we often call them methods. In other words, serial object takes the begin method. It is created to establish connection with the second device, which in our case is a computer. It can be called through setup and this happens only once when the controller starts. On the other hand, the parameter that we pass 9,600 is the data transfer rate in BD, which shows units, equivalent to bps in digital data exchange. 9,600 bps is not a lot but quite enough to transmit our small amounts of data. If you wish, you can increase the speed to let's say 115,200 but you will hardly ever need it, anyway. Now, let's try to understand where we can access the serial object next. This already happens in the loop. So we have to call another method called "print in" to which we pass the sensor value parameter. This parameter is a variable used by us to save our data in it which we received from A-0 analog output. One can guess that the printing is responsible for outputting a line in the serial port. It needs to be remembered that it adds a line feed at the end of the line. Namely, there is one more print method which will output your data and will not be translating your line, whereas, the subsequent data will be output right after your data. Let's conduct a small experiment with you. We are just going to output some data through a serial port and we shall see what it will look like. I have prepared and experimental sketch for you. Let's see what I've written here. We have connection being established at the same speed and then the transliterated line Privet is output directly to set up. Communication in Cyrillic might not work out. So let's try to output Latin characters. Thus, at the beginning of the sketch, we will have the Privet word and then we will output a certain value in the loop with the print method. We got casually acquainted with one small but useful function, which makes part of the Arduino language. This function is called millis. It returns the number of milliseconds which have passed since the controller was started. This might often come in handy and you can see right now what it looks like. You will output the number of milliseconds which have passed since the controller was started. Then without translating the line you will output the following thing. Let me underline this. This is the so-called "escape sequence" and it's not going to be output in the same form as we wrote it. When the Port Monitor gets the backward slash, it will realize that this is the beginning of the escape sequence and it will output a certain symbol which we would not be able to write manually. This is a tab character. With it, you can easily format your output data for the serial port. In other words, we will output the number of milliseconds and then the tab character and it will look like a number of spaces. I've created a little delay of 0.5 seconds so that the data wouldn't be displayed too fast. The loop then begins again and outputs a new value which returns the millis. Let's see what it will look like. I'm going to start the Port Monitor. Privet 0 499 999 and then we can see the data which is output every 500 milliseconds. Sometimes, this number is increased by one millisecond because all the actions that the controller runs will also take some time. That's why sometimes an extra millisecond appears, which is later added to the output number. So now you understand how to output data to a serial port. Later this week, we are going to talk about how we can read data which is sent from a computer. For now, we've just figured out how our experiment works. The one we've been working on all this time. Now, I'm going to close the Port Monitor, you too, don't forget to do it. Once you're done with your data reading, as it might seriously disturb your work process when you are downloading a new sketch.

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