I²C Communication with AT24C02B EEPROM using Bus Pirate

Requirements

Bus Pirate (any version that supports I²C)
AT24C02B EEPROM chip
Jumper wires
Breadboard
Power supply (3.3V or 5V, depending on the EEPROM voltage)
Serial terminal software (e.g., PuTTY, Tera Term, or Linux/Mac terminal)

Setup

Wiring the AT24C02B to the Bus Pirate

Bus Pirate Pin	AT24C02B Pin	Function
3.3V or 5V	VCC	Power supply for the EEPROM
GND	GND	Ground
MOSI	SDA	I²C Serial Data
CLK	SCL	I²C Serial Clock
CS	WP	Connect to GND (write-protect disabled)
(Optional)	A0, A1, A2	Tie to GND for default I²C address (0x50)

Note: Pull-up resistors (typically 4.7kΩ) should be connected to SDA and SCL lines. If your Bus Pirate has pull-ups, enable them via software.

Step-by-Step Guide

1. Enter I²C Mode

To enter I²C mode, type the following commands:

HiZ> m      # Enter the mode selection menu
4           # Select I²C
3           # Operate at 100 kHz (Standard mode)

You should see:

I2C>

2. Enable Pull-Up Resistors

Activate the pull-up resistors with:

I2C> p

3. Scan for I²C Devices

To scan for devices on the I²C bus, use the following command:

I2C> (1)

If the AT24C02B is connected, you should see:

I2C> Devices found: 0x50

4. Write Data to the EEPROM

To write a byte (e.g., 0x42) to address 0x00:

I2C> [0xA0 0x00 0x42]

Explanation:

[: Start condition
0xA0: Write command (I²C address 0x50 shifted left + write bit)
0x00: Memory address
0x42: Data to write
]: Stop condition

Wait 5ms to complete the write cycle.

5. Read Data from the EEPROM

To read the byte back from address 0x00:

I2C> [0xA0 0x00]

Then, to read the data:

I2C> [0xA1 r]

You should see:

0x42

6. Perform Sequential Reads

To read multiple bytes (e.g., 4 bytes starting at address 0x00):

I2C> [0xA0 0x00] [0xA1 rr rr rr rr]

The "rr" command reads each subsequent byte, separated by repeated start conditions.

Troubleshooting

If the EEPROM is not detected, check your wiring and ensure the correct power supply is used.
For write errors, ensure the WP (write-protect) pin is connected to GND.

Conclusion

Using the Bus Pirate, you can easily interact with the AT24C02B EEPROM to write, read, and test data over I²C. This setup is perfect for debugging and learning I²C communication protocols.

If you need help automating this with scripts or more advanced examples, feel free to ask!