Yes, the FRAM loses info after a read, and must be written back. Thankfully, the MSP430 FRAM handles the process automatically. You can find more info in http://www.ti.com/lit/an/slaa649/slaa649.pdf
Hereunder an excerpt from it:
... In the process of reading the data, the crystal that is polarized in the
direction of the applied field loses its current state. Hence, every read must be accompanied by a writeback
to restore the state of the memory location. With TI's MSP430 FRAM MCUs, this is inherent to the
FRAM implementation and is completely transparent to the application. ...
BestPosted on: February 28, 2015, 12:02:34 00:02 - Automerged
The standard I2C FRAM datasheet from Fujitsu don't mention the rewrite process. But at Spansion (which is Fujitsu!), they describe it, in chapter 3.2 of the following document (The number of Rewrite operations)http://www.spansion.com/marketingdownloads/appnotes/public/fm3/an706-00053_control_fram_by_i2c_and_spi/an706-00053-1v0-e.pdf