Introduction

Building DIY electronic projects is an exciting way to explore the world of circuit design, digital electronics, and the endless possibilities of integrating hardware and software. One key aspect of many digital circuits is the ability to control multiple outputs with minimal inputs, known as multiplexing. In this guide, we will focus on a project built using the CD4502BM96E4, a digital output latch chip, which is highly versatile and essential for controlling devices such as LEDs, motors, and displays.

The CD4502BM96E4 is an 8-channel tri-state buffer that can store and output data from a digital circuit. The chip is primarily used for applications where multiple outputs need to be managed with precise control, making it suitable for use in multiplexers, LED matrices, memory addressing, and other logic circuit designs.

What is the CD4502BM96E4?

The CD4502BM96E4 is an 8-bit, 3-state output latch, which means that it can store and lock 8 bits of data simultaneously and control the output of these 8 bits through its tri-state outputs. It has three output states:

· High

· Low

· High Impedance (Z)

The high-impedance state allows the output to be effectively disconnected, making it useful for applications where multiple devices share the same output lines. This chip is particularly useful in controlling large sets of digital outputs while using fewer pins on a microcontroller, making it an excellent choice for multiplexing or controlling arrays of devices like LEDs, sensors, or relays.

Key features of the CD4502BM96E4 include:

· 8-bit parallel output

· 3-state control (enabled or high-impedance state)

· Wide voltage supply range (3V to 18V)

· Low power consumption

· Easy to interface with microcontrollers and other digital logic circuits

Project Overview: Digital Control of LED Matrix Using CD4502BM96E4

This DIY project will guide you through designing and building a digital control system for an 8x8 LED matrix using the CD4502BM96E4. The idea is to use the chip to control individual rows or columns of an LED matrix while reducing the number of pins required from the microcontroller. By using multiple latches and multiplexing techniques, the CD4502BM96E4 allows you to manage the LEDs with precision.

In this project, you’ll use an Arduino to interface with the CD4502BM96E4, sending data that is latched into the outputs and used to control the LED matrix. This project is not only a great way to explore digital logic and multiplexing but also a perfect introduction to building more complex digital systems like displays or switch matrices.

Materials Required

· CD4502BM96E4 8-Bit Latch (1 or 2 pieces, depending on matrix size)

· Arduino Uno (or any compatible microcontroller)

· 8x8 LED matrix (or 8 LEDs for demonstration)

· Resistors (220Ω or 330Ω for current limiting)

· Breadboard and jumper wires

· 5V Power Supply (or power directly from the Arduino)

· Capacitors (0.1μF for decoupling)

· Push buttons (for manual control or debugging)

Understanding the Pinout of CD4502BM96E4

Before we dive into the construction of the project, it's important to familiarize ourselves with the pinout of the CD4502BM96E4:

· Pins 1-8 (Q1-Q8): These are the eight output pins, each corresponding to one of the 8-bit inputs.

· Pins 9-16 (D1-D8): These are the data input pins. The data from these pins is latched into the corresponding output when enabled.

· Pin 11 (Latch Enable): This pin enables or disables the latch. When it's LOW, the data from the input pins (D1-D8) is stored and passed to the output pins (Q1-Q8).

· Pin 13 (Output Enable): This is the control for the tri-state output. When it's HIGH, the outputs are disabled (high-impedance state). When it's LOW, the outputs are active.

· Pin 10 (GND): Ground pin.

· Pin 14 (VCC): Power supply pin, which can be between 3V and 18V, but typically, it will be 5V when using a microcontroller.

Step-by-Step Instructions

Step 1: Setting Up the Circuit

For this project, you’ll connect the CD4502BM96E4 to the Arduino to control an 8x8 LED matrix. The CD4502BM96E4 will control which rows of the LED matrix are active at any given moment, while the columns will be directly driven by the Arduino. This method reduces the number of microcontroller pins needed to control the entire matrix.

Connecting the CD4502BM96E4:

Power the Chip:

o Connect pin 14 (VCC) to 5V from the Arduino, and pin 10 (GND) to ground.

Input Pins (D1-D8):

o Connect pins 9-16 (D1-D8) of the CD4502BM96E4 to 8 digital pins on the Arduino (e.g., pins 2 through 9). These will serve as the data inputs for the latch.

Latch Enable:

o Connect pin 11 (Latch Enable) to another digital pin on the Arduino (e.g., pin 10). The Arduino will toggle this pin HIGH or LOW to latch the data into the output.

Output Enable:

o Connect pin 13 (Output Enable) to the Arduino (e.g., pin 11). The Arduino will control this pin to enable or disable the outputs.

Output Pins (Q1-Q8):

o Connect pins 1-8 (Q1-Q8) to the rows of the 8x8 LED matrix. Each output will control one row of the matrix.

Resistors:

o Connect 220Ω or 330Ω resistors between the output pins and the rows of the LED matrix to limit the current through the LEDs.

Columns of the LED Matrix:

o Connect the columns of the LED matrix directly to 8 other digital pins on the Arduino.

Step 2: Writing the Code

Now that the hardware is set up, let’s write the Arduino code to control the CD4502BM96E4 and the LED matrix. The idea is to send data from the Arduino to the CD4502BM96E4 to light up specific rows, while the Arduino controls which columns are active at any given moment.

Here’s a simple Arduino sketch to demonstrate this: