4.13. Errors that we often encounter

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From the course by Moscow Institute of Physics and Technology

Building Arduino robots and devices

135 оценки

Moscow Institute of Physics and Technology

Building Arduino robots and devices

135 оценки

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

From the lesson

Week 4

After going through Week 4, you will be able to connect your device to a network, plan its creation beforehand , control heavy loads, and power your device correctly.

4.1. Week overview0:50

4.2. Submersible pump2:02

4.3. Field transistor and relay6:40

4.4. Power supply6:47

4.5. Planning6:07

4.6. Think first7:46

4.7. Soil humidity sensor2:16

4.8. Where do web pages come from4:10

4.9. How to transmit data to a network11:35

4.10. How to receive a command from a network8:14

4.11. Finite-state automaton5:13

4.12. WaterMe program basics and switch7:18

4.13. Errors that we often encounter7:03

4.14. The longest sketch so far12:31

4.15. How WaterMe works5:20

Meet the Instructors

Алексей Перепелкин
Руководитель направления развития цифрового творчества
Центр инновационных образовательных технологий МФТИ
Дмитрий Савицкий
Научный сотрудник
Лаборатория инновационных образовательных технологий МФТИ

Before we begin assembling our watering system, let’s take

some rest and talk about the most frequent errors we

can encounter when we work in the Arduino development environment.

I am going to take our automate template, which was initially

incomplete, and will try to compile it.

We are immediately getting a lot of error messages.

I want you to stop fearing this console where these messages

are output and start reading what is actually written there.

It would surely be useful if you spoke some English, but if not,

you can simply remember what the most common error messages look like.

The messages keep telling us that “WebRequest”,

“CheckClimate”, “CheckWater”, “Watering”, “Alarm”,

and “SendPage” – all these functions were not declared in this scope.

Here is this message.

You may get a similar message concerning functions or variables.

Thus, if you don’t define a function, the compiler will punish you for it.

If you have invented this function by yourself, make sure you check how you defined it, i.e.

if you wrote a definition.

If you are using a library function, make sure you’ve connected the library,

and placed the files in the library in the right places.

Arduino usually stores them in the “My documents” folder in Arduino Libraries.

Besides, you might be getting this error message if you are trying to call an existing function,

but you are doing it incorrectly.

Check if you’ve written the name of the function correctly.

The same happens with variables.

However, you’ll also need to take their scope into consideration.

Remember, we were talking about global and local variables?

If you are trying to call from a function a local variable declared in another

function, an error message will appear.

The same will happen if you’ve forgotten to declare a variable and you are

trying to refer to it.

What other frequent errors can we encounter?

I’ll leave this automate sketch alone for a moment in order not to spoil it somehow.

And I’ll take our standard Blink sketch

[PAUSE] and

will disfigure it a tiny bit.

Like, I can forget to put the curly bracket, and then

try and compile the sketch.

An error message appears again.

If we throw a glance at the sketch,

we can see at once that one curly bracket is missing.

Please, make sure you check that your curly brackets are always paired.

I’ll put this bracket back, but once again I recommend that you format

your code attentively, i.e. after the opening curly bracket,

you need to add Tab space, and with the closing bracket,

the same happens but in the opposite manner.

Thus, it’ll be easier for you to see if the two brackets are paired with each other.

I’m putting back the bracket, but let’s imagine that I forget the semi-colon.

The message explicitly shows us

that a semi-colon before the curly bracket is necessary.

When you call a function,

you might see an error message concerning unpaired parentheses.

If we are transmitting the calling of another function as a parameter,

we need to first close the parentheses of the internal function,

which is transmitted with a parameter, and then the parentheses of the function to which our internal function is transmitted.

Don’t forget about paired parentheses.

Besides, when you are calling a function,

you need to transmit to it as many parameters as it is expecting.

Well, I think, this is quite obvious.

you may also get a message that a

different number of parameters was expected.

I often get such errors from the compiler,

but sometimes there occurs an error which the compiler ignores,

since it thinks that nothing looks wrong there.

This happens when you confuse “=” with “= =”.

“=” is the assignment operator that

places whatever there is to the right of it,

to the section which is to the left of it.

“= =” is the boolean comparisons operator, which checks if the values are equal.

We may often forget in the if-clause about

the double equals sign and write, for instance, if (a = b).

In this case, comparison will not take place, and the result of this

action will not be boolean “1” if a=b,

but “а” will equal “b” in any case.

Thus, you will assign the “b” value

to the “a” variable.

You mustn’t forget about that either.

Finally, when we work with Arduino, apart from program code errors

we might also have errors concerning the upload of the sketch to the board.

The most frequent reason for errors is when we forger to connect the wire.

You might also forget to check

whether you’ve chosen the right board model or marked the port

which appears when we connect the board.

If it all seems fine, there may occur some situations when somewhere in the circuit,

a short-circuit failure happens, and the voltage regulator

cuts off the connection with the computer in order not to mess up your USB.

In that case, remove all your expansion cards,

turn off all the components and try to upload the sketch.

If nothing happens, look for the short-circuit failure in your circuit.

Last but not least, when you forget to shut down the Port Monitor or

the analog signal visualizer, you

won’t be able to upload a new sketch either. So you will need to make sure you shut them down.

Naturally, these are not all the

probable errors that we might experience,

but we have definitely covered the better part of them.

I hope that they won’t bother you too much when you practice.

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