字幕列表 影片播放 列印英文字幕 Hi my name is Massimo Banzi and I like to make stuff. Today we are here to look at another project from our Arduino Starter Kit. Today we are making this spaceship interface. This is a simple project designed to teach you about simple inputs and outputs with Arduino. This circuit is going to show you how simple it is to connect a small button and a set of LEDs to the Arduino board, and how you can control the LEDs through the button. First I want to explain a few concepts about Arduino. First of all Arduino is the size of a credit card as you can see here. We can program using the Arduino development environment that I am going to show you in a few minutes. The idea is that we write instructions in the development environment, then we press the button that turns the instructions into a program and get downloaded into the Arduino. Then the Arduino can interface with the outside world to implement any crazy projects that you can come up with. So this project is very simple. We have a button connected to pin number 2 on the Arduino, and then we have three LEDs connected to pin 5, 4 and 3 of the Arduino. When I press the button, these two LEDs that are now blinking will stop blinking, and the yellow LED will turn on. If I release the button the two LEDs will keep blinking. So, this is a very simple circuit that allows us to control the behavior of these 3 LEDs from this button. Let's have a look to the code that we need to implement this behavior. At the beginning of the code we have this line that says const int redLed1 = 5, so this creates a constant called redLed1 that contains the value 5. This is actually a very clever technique that allows us to give a meaningful name to pin numbers. So, throughout the code I don't have to use the numbers but I can use redLed1 to remember that particular pin is associated with the first red LED. And if you look, there are another couple of lines where you defined constant for redLed2 and greenLed. Then, later on we have another constant called switchPin = 2. This specifies that a switch or a button that we are using is connected to pin number 2. Then let's look at the setup. The setup() is that part in your Arduino code that gets executed once when the board is powered on or reset, This means also right after you upload some code into the Arduino. So, as I said, this gets executed only once. We see the instruction pinMode(). pinMode() basically tells Arduino that we want to make sure that pins, redLed1, redLed2 and greenLed are all configured as outputs, because the input and the output pins of the Arduino can be configured to assume both configuration. Then we have an instruction called pinMode(switchPin, INPUT), which is used to specify that the pin number 2 is connected to a switch. And then we want to make sure that is an input so we can read from it. Now let's have a look of the loop section. The loop section in your code gets executed over and over as long as the board is powered on. We created a variable called switchState and then we say switchState = digitalRead(switchPin) Basically what this does is to read the state of the pin connected to the pushButton and it returns a value HIGH or LOW depending on the fact that the button is pressed - HIGH - or released - LOW Then we are going to use a clever statement called if, which is very important whenever you write some code because this "if" statement allows us to take decisions. In this particular case we basically ask Arduino if (the switchState == LOW) do something. So in this case, we used curly brackets to group lines of code together. You can see that this "if" statement is followed by a question, a condition that needs to be verified. and then the curly brackets specify which lines of code need to be executed when the condition is true. In this case, switchState == LOW; basically says if the button is not pressed, and then we follow that with a series of digitalWrite() statements that are used to turn on and off the LEDs and to implement this particular blinking behavior. After that we have a delay of 250 milliseconds followed by a short blink cycle that happens on the other red LEDs. The instructions that you see in this section of the "if" statement are used to implement this blinking behavior that you see here. Afterwards, there is a statement called "else". Else is a statement that allows you to basically create a fork in the road in your Arduino code. With "if" you can say if something is true, execute this piece of code. And else says if that condition is not true, then execute this other piece of code. So you can have two different paths of your code that get executed depending on the condition, if that condition is true or false. In this case, when the button is pressed then we use two digitalWrite() to turn off the red LEDs. And we use one digitalWrite(greenLed, HIGH) to turn on the green or yellow LED like we have here. So if I press the button, the LED turns on. If I release the button, the LEDs are blinking. So this is all the code that we need in order to implement this behavior. I want to remind you that the code that's inside the loop statement will be executed over and over. so as you can see the blinking pattern is executed. Then Arduino reads the input, checks if it's true or false. So depending on that it decides which behavior to implement and then loops back from the beginning. That's all for today. I hope you enjoyed the tutorial. And remember: build it, hack it, share it, because Arduino is you!
B1 中級 Arduino視頻教程02:宇宙飛船的接口 (Arduino Video Tutorial 02: Spaceship Interface) 280 1 Chuan Zhe Lin 發佈於 2021 年 01 月 14 日 更多分享 分享 收藏 回報 影片單字