80. Persistencia de la visión ****PIC16F887****

Introduction

In this video, we will be discussing the persistence of vision and how it relates to circuits. We will explore how our eyes and brain work together to interpret images and how this can be applied in displays such as seven-segment displays.

How Our Eyes Work

• The retina is the part of our eye that is sensitive to light.

• The majority of sensors in our eyes are called rods, which allow us to see in grayscale.

• Cones are a minority of sensors that allow us to see colors.

• Our brains interpret combinations of red, green, and blue light to create other colors.

Persistence of Vision

• When we see an image, there is a delay between when the light hits our eyes and when our brains interpret it.

• This delay helps our brains create continuity between images, making them appear seamless.

• This process can be used in displays such as seven-segment displays.

Applying Persistence of Vision in Circuits

• Connecting all segments of a display directly to a microcontroller would require too many pins.

• Instead, we can connect segments together and use resistors to control their connection to the microcontroller.

Conclusion

In conclusion, understanding how our eyes and brain work together can help us design more efficient circuits. By using persistence of vision, we can create displays with fewer pins while still maintaining functionality.

Working with Display Segments

In this section, the speaker explains how to work with display segments and how to activate them one at a time.

Activating Display Segments

• The data port sends information to all segments.

• Only one segment is activated at a time through its common terminal.

• To activate a segment, first place the desired data in the data port.

• Then, activate the corresponding transistor for that digit.

• After a set amount of time, deactivate the transistor so that all segments are off again.

• Repeat this process for each digit.

Time Perception and Display Refresh Rates

• The human eye processes images in about 1/20th of a second.

• For larger images like those in movies, a refresh rate of 24 frames per second is sufficient.

• However, for smaller displays like seven-segment displays, a faster refresh rate may be necessary to avoid flickering or incomplete activation of segments.

• A total refresh rate of 1/160th of a second (60Hz) is recommended for small displays.

Importance of Fast Refresh Rates

• Even with fast refresh rates, rapid eye movements can still cause incomplete activation or flickering on small displays.

• To combat this issue, even faster refresh rates may be necessary.

• A total refresh rate of 1/240th of a second (30Hz) may be sufficient for some applications.

Perception of Image Reflection

In this section, the speaker discusses how our perception affects our ability to see images on small displays and recommends ways to improve image quality.

Improving Image Quality on Small Displays

• A video demonstration shows that even when all segments are activated, small displays may still appear to vibrate or flicker.

• To improve image quality on small displays, a faster refresh rate is recommended.

• A total refresh rate of 1/160th of a second (60Hz) is recommended for small displays.

Display Circuit Construction

In this section, the speaker discusses how to construct a display circuit. They explain the diagram of a development board and how to control it.

Connecting the Data Port

• The data port is connected to the output of the data port.

• A resistor with a value that depends on the characteristics and color of your display should be used.

• Displays that are opaque are more convenient because they do not reflect light and appear brighter.

Transistor Control

• To control current flow from collector to emitter, there must be current flow from base to emitter.

• When a 1 is inputted into the control port, all transistors will be in cutoff mode.

• When a 0 is inputted into the control port, only one transistor will be in saturation mode.

Using Simple Transistors

• Very little current is needed to control LEDs with simple transistors.

• The saturation voltage between collector and emitter would be 0.1 volts.

Introduction to Transistors

In this section, the speaker introduces transistors and explains how they work. They also discuss the importance of beta in determining the amount of base current required to saturate a transistor.

Understanding Beta

• Beta is an important factor in determining the amount of base current required to saturate a transistor.

• If a transistor has a high beta value, it requires less base current to saturate.

• To calculate the necessary resistance for a given beta value, divide the voltage by the required base current.

• For circuits with common nodes, resistors are recommended over other components.

Controlling Transistor Flow

In this section, the speaker discusses how to control transistor flow using logic gates and resistors.

Using Logic Gates

• Logic gates can be used to control transistor flow by applying either a 0 or 1 signal.

• If all signals are set to 0, no current will flow through any of the transistors.

• By setting one signal to 1 and all others to 0, only one specific segment will light up on an LED display.

Building a Counter Circuit

In this section, the speaker explains how to build a counter circuit that displays numbers from 0 to 99 on an LED display.

Building the Circuit

• The circuit uses cátodo común LEDs and is designed as a repetitive counting system.

• Once built, the circuit can be expanded to count higher numbers by adding additional components.

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Cómo optimizar el rendimiento de una aplicación web

En este video se explica cómo mejorar el rendimiento de una aplicación web. Se habla sobre la importancia de reducir el tiempo de carga y se dan consejos para lograrlo.

Consejos para reducir el tiempo de carga

• Una forma de reducir el tiempo de carga es minimizando la cantidad de recursos que se cargan en la página.

• Otra forma es comprimir los archivos CSS y JavaScript para que sean más pequeños y se carguen más rápido.

• También es importante utilizar un sistema de caché para almacenar temporalmente los recursos que ya han sido cargados, lo que reduce el tiempo necesario para cargarlos nuevamente.

• Por último, se recomienda utilizar un servicio CDN para distribuir los recursos a través de múltiples servidores, lo que reduce la latencia y mejora el tiempo de carga.

Conclusiones

• Reducir el tiempo de carga es fundamental para mejorar el rendimiento de una aplicación web.

• Para lograrlo, es importante minimizar la cantidad de recursos que se cargan en la página, comprimir los archivos CSS y JavaScript, utilizar un sistema de caché y un servicio CDN.