A cosa serve l'istruzione analogWrite di Arduino e cos' un PWM – Video Arduino #5
Understanding the concept of PWM (Pulse Width Modulation)
What are PWM pins?
PWM pins, or Pulse Width Modulation pins, are those marked with a tilde (~) or a squiggly line. On most Arduino boards, pins 3, 5, 6, 9, 10, and 11 are PWM pins. These pins can emit a specific signal called PWM, which stands for Pulse Width Modulation. It is a square wave that is used to control devices such as motors and LEDs to create the illusion of varying brightness levels. Unlike analog pins, which can output any voltage between 0 and 5 volts, PWM pins can only output a voltage that is either 0 or 5 volts, with no in-between values.
How does PWM work?
PWM works by rapidly turning the output voltage on and off at a high frequency. The LED, for example, is turned on and off so quickly that the human eye perceives it as being on with a certain brightness level, even though it is actually flickering. The eye averages out the on and off periods, creating the illusion of a varying brightness level. This is how PWM is utilized to control the brightness of an LED.
Implementing PWM in practice
To implement PWM in practice, you will need an Arduino board, a LED, and some basic programming skills. Start by preparing the LED: slightly bend its legs so that the cathode (the negative leg) is longer than the anode (the positive leg). Insert the cathode into pin 11, which is a PWM pin. Once the LED is connected, open the Arduino software and create a new sketch.
Writing the code
In the sketch, eliminate any unnecessary comments and go directly to the loop part. To turn on the LED, use the analogWrite command, which will appear in orange in the Arduino software. This command requires two parameters. The first parameter is the PWM pin number you want to use, which in this case is 11. The second parameter is the brightness level, which is a number between 0 and 255. A value of 0 will completely turn off the LED, while a value of 255 will maximize its brightness. You can use any other value in between to generate different brightness levels.
Experimenting with different brightness levels
To experiment with different brightness levels, try inserting a value much lower than 255 into the analogWrite command. For example, you can try using a value of 10, which will result in a very low brightness level for the LED. After writing the code, verify it for any errors and then save it.
By implementing PWM with Arduino and a LED, you can control the perceived brightness level and create various lighting effects. This technique is widely used in projects where precise control of light intensity is required, such as in dimmable lamps or LED displays.
The Importance of Sketches in Uploading and Modifying
Sketches play a vital role in the world of programming. They serve as the foundation for building and developing various applications and devices. Sketches are used to create code that can be uploaded to microcontrollers such as Arduino, allowing users to modify and control their projects. In this article, we will explore the significance of sketches and their role in uploading and modifying code.
The Power of Upload and Modify
One of the key advantages of using sketches is the ability to upload and modify code easily. Whether you want to change a specific variable or experiment with different functions, sketches give you the flexibility to make those changes. For example, you can modify the brightness of a LED by adjusting a variable in the sketch and then verify the upload to see the desired effect. This ability to modify code on the fly allows for efficient troubleshooting and customization.
Controlling LEDs and Motors
Sketches are particularly useful for controlling devices such as LEDs and motors. These devices often operate in a binary manner, either being turned on or off. However, in the case of LEDs, simply providing half the voltage they require may not yield optimal results. LEDs function best when supplied with their precise operating voltage. The same principle applies to motors; they need to run at their nominal voltage for optimal performance.
Gradual Illumination with Analog Brightness
Analog brightness control is a technique that allows for gradual illumination of an LED. It involves rapidly turning the LED on and off within a specific time interval, resulting in an average brightness that corresponds to a certain percentage of the LED’s full capacity. Arduino provides examples of this technique, and you can find sample sketches that demonstrate how to achieve analog brightness. It’s a captivating effect that adds visual appeal to your projects.
Understanding Pin Usage
It’s important to note that when working with sketches, each device or component is assigned a specific pin on the microcontroller. For example, the LED mentioned earlier was connected to pin 11. This pin assignment is crucial as it dictates which input/output port is used to control the component. Understanding how to interact with different pins and assigning them correctly is essential for achieving the desired functionality.
Sketches serve as the building blocks of code for various projects and devices. They allow for easy uploading and modification, enabling programmers to fine-tune their projects and troubleshoot efficiently. Sketches are particularly valuable when controlling devices like LEDs and motors, offering precise control over their operation. So, whether you’re a beginner or an experienced programmer, understanding the power of sketches and their ability to bring your projects to life is essential.