- 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
All pins are 3-5V compliant and use whatever logic level is on VCC
- HOLD - this is a 'wait' pin for the SPI bus. When pulled low, it puts the SPI bus on hold. This is different than the CS pin because it doesnt stop the current transaction. Its good if you want to talk to other SPI devices and stream data back and forth without stopping and starting transactions.
- SCK - This is the SPI clock pin, its an input to the chip
- MISO - this is the Microcontroller In Serial Out pin, for data sent from the FRAM to your processor
- MOSI - this is the Microcontroller Out Serial In pin, for data sent from your processor to the FRAM
- CS - this is the chip select pin, drop it low to start an SPI transaction. Its an input to the chip
- WP - Write Protect pin. This is used to write protect the status register only! This pin does not directly affect write protection for the entire chip. Instead, it protects the block-protect register which is configured however you want (sometimes only half the FRAM is protected)