Using an EEPROM to replace combinational logic

Introduction

In this tutorial, we will learn how to use a 28C16 EEPROM to replace combinational logic circuits, specifically focusing on how to read and program the EEPROM. This guide will walk you through the wiring process, programming values, and how to implement the EEPROM as a substitute for logic components like a 7-segment decoder.

Step 1: Gather Necessary Components

Before you begin, ensure you have all the required components. Here’s a complete parts list:

• 1x 28C16 EEPROM
• 8x LEDs
• 8x 330Ω resistors
• 1x 8-position DIP switch
• 1x 4-position DIP switch
• 12x 10kΩ resistors
• 1x 100nF capacitor
• 1x 680Ω resistor
• 1x momentary tact switch
• 1x Common Anode 7-segment display
• 1x 100Ω resistor

Having all components ready will streamline the process.

Step 2: Wire Up the EEPROM

To connect the EEPROM to your breadboard or circuit, follow these steps:

1. Identify Pins on the EEPROM: Familiarize yourself with the pin configuration from the EEPROM’s data sheet.
2. Connect Power and Ground:
   • Connect Vcc (pin 28) to +5V.
   • Connect GND (pin 14) to ground.
3. Setup Control Pins:
   • Connect A0 to A4 (address pins).
   • Connect chip enable (CE) and output enable (OE) pins as specified in the data sheet.
4. Connect Input/Output Pins: Wire the data pins (D0 to D7) to your circuit for reading and writing data.

Step 3: Program the EEPROM

Programming the EEPROM involves writing data to it. Here’s how you can do it:

1. Consult the Data Sheet: Understand the programming sequence and requirements.
2. Prepare Data: Decide on the values you want to store. For example, to program a value for a 7-segment display, you might want to store values corresponding to digits 0-9.
3. Writing Process:
   • Use your DIP switches to select the binary input.
   • Activate the programming mode by setting the appropriate control pins.
   • Use a momentary switch to trigger the write operation.

Step 4: Read Values from the EEPROM

After programming the EEPROM, you will want to read the values back:

1. Setup for Reading: Ensure the control pins are set correctly for reading mode.
2. Access Data:
   • Use the DIP switches to select the desired address.
   • Observe the output on the connected LEDs or 7-segment display to see the stored value.

Step 5: Implement the 7-Segment Decoder

To replace a combinational logic circuit like a 7-segment decoder:

1. Connect the 7-Segment Display: Wire the 7-segment display according to your circuit design.
2. Map Inputs to Outputs: Program the EEPROM to output the correct signals for each digit based on the binary input from the DIP switches.
3. Test Functionality: Switch the DIP inputs and verify that the correct segments light up on the display.

Conclusion

In this tutorial, we've covered how to wire, program, and utilize a 28C16 EEPROM to replace conventional combinational logic circuits. This approach allows for flexible and reusable logic in your electronic projects.

For next steps, consider experimenting with different values or expanding your project by integrating more complex combinational logic scenarios. Happy tinkering!