The FRAM chip is the little guy in the middle. On the bottom we have the power and interface pins
- VCC - this is the power pin. Since the chip uses 3-5VDC you should pick whatever the logic voltage you're using. For most Arduino's that's 5V.
- GND - common ground for power and logic
- WP - Write Protect pin. This is used to force write protection so you cannot write to the FRAM. It has an internal pulldown. Bring to a high voltage (VCC) to turn on WP
- SCL - I2C clock pin, connect to your microcontrollers I2C clock line.
- SDA - I2C data pin, connect to your microcontrollers I2C data line.
A2, A1, A0 - These are the I2C address selection pins. By default the I2C address is 0x50. Connecting these pins to VCC and power cycling the chip will adjust the lower three bits of the address. For example, if A0 is high, the address is 0x51. If A1 and A2 are high, the address is 0x56