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3.2.4 FRAM EEPROM
The F-RAM memory is present to allow the option of logging (data) to a local memory that is not part of
the Raspberry Pi disk drive. This supports evaluation of some of the possible end application uses of the
CAN Interface pHAT.
F-RAM is a type of non-volatile memory (EEPROM) based on ferro-electric memory technology. Another
technology with similar functional characteristics is Spintronic memory (Manufactured by Everspin).
F-RAM technology allows fast writes (without the significant delay seen with typical EEPROM) and has
the characteristic that the part doesn't suffer from appreciable 'wear': the device can be written to
without the endurance issues typical of standard types of EEPROM – the spec states it has a write
14
endurance of 10
.
The part fitted to the board is a Cypress device (previously Ramtron) part number FM25CL64B-DG, this
shares a common footprint with the 25C080SN shown.
Internally the part is 64kBit, this is arranged as 8192 x 8 bits (Bytes).
It is intended that the part could be used as a part of a logging system – with the memory being written
continually whilst the system is powered. If sensible check sums or other state values are used, it should
be possible to minimise data loss during power down events.
The SPI programming commands are described in the Cypress datasheet [3].
Figure 6 - FRAM Memory
01/06/2018
Document Number
IEMAN000001
Document Title
CAN Interface pHAT User Manual
11 of 22
Document Revision
Page
R003
11 of 22
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