Eeprom16

🧠 8-bit EEPROM Programmer & Display Decoder

This project implements an EEPROM-based lookup table to convert an 8-bit value into decimal digits using a hardware-only decoding approach.

The EEPROM is programmed using an Arduino Nano Every and a shift-register-driven address bus.

📌 Overview

The system:

• Converts 0x00–0xFF into decimal digits
• Supports both unsigned and two’s complement signed formats
• Uses EEPROM as a hardware lookup table
• Drives a segmented display via precomputed values

⚙️ Architecture

• MCU: Arduino Nano Every (20 MHz)
• Shift Register: 74HC164 (serial → parallel address)
• EEPROM: AT28Cxx family
• Data bus: 8-bit parallel
• Control signals: WE, OE, CLR

Addresses are shifted serially into the 74HC164, while data is written in parallel.

🧩 EEPROM Memory Map

Unsigned (0x00–0xFF)

Signed (-128 → 127)

• Digits use abs(value)
• Negative numbers use sign byte 0x80

🔢 Segment Encoding

🛠️ Programming Flow

For each byte:

1. Clear shift register
2. Shift 11-bit address (MSB → LSB)
3. Set data bus (D0–D7)
4. Pulse WE (write enable)
5. Wait for write cycle (~2 ms)

Readback uses the same address logic with OE enabled.

⚡ Timing Notes

• Arduino @ 20 MHz → ~50 ns per cycle
• digitalWrite() already satisfies all timing constraints
• EEPROM write cycle dominates (~1–2 ms)
• No latch in 74HC164 → register is cleared before each address load

🖼️ Assets

Schematic

PCB

3D View

Gerbers

📁 Structure

.
├── firmware/
├── hardware/
├── images/
└── README.md