TS-7180 FRAM: Difference between revisions
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The EEPROM | <!--The 7553v2 and 7840 transclude the page {{:FM25L16B_FRAM}. For the 7100 and 7180, some of it is inadequate or wrong. --> | ||
The Cypress FM25L16B provides 2 KB of non-volatile memory in a manner not unlike an SPI EEPROM. However, the nature of ferro-electric RAM (FRAM) means it is incredibly fast to write, and is specified with 100 trillion read/write cycles per each byte and a 150 year data retention at temperatures below 65 ℃. | |||
The FRAM can be accessed as a flat file from Linux: | |||
<source lang=bash> | |||
# xxd -a /sys/class/spi_master/spi2/spi2.2/eeprom | head | |||
00000000: 0000 0000 0000 0000 0000 0000 0000 0000 ................ | |||
* | |||
000007f0: 0000 0000 0000 0000 0000 0000 0000 0030 ...............0 | |||
# | |||
</source> | |||
If U-Boot's [http://www.denx.de/wiki/view/DULG/UBootBootCountLimit bootcount tracking] environment variable is enabled, the last byte of FRAM is reserved for storing the boot count, and care should be taken to not overwrite it inadvertently. In U-Boot, the boot count can be accessed with the 'fram' command. | |||
Revision as of 17:50, 19 July 2022
The Cypress FM25L16B provides 2 KB of non-volatile memory in a manner not unlike an SPI EEPROM. However, the nature of ferro-electric RAM (FRAM) means it is incredibly fast to write, and is specified with 100 trillion read/write cycles per each byte and a 150 year data retention at temperatures below 65 ℃.
The FRAM can be accessed as a flat file from Linux:
# xxd -a /sys/class/spi_master/spi2/spi2.2/eeprom | head
00000000: 0000 0000 0000 0000 0000 0000 0000 0000 ................
*
000007f0: 0000 0000 0000 0000 0000 0000 0000 0030 ...............0
#
If U-Boot's bootcount tracking environment variable is enabled, the last byte of FRAM is reserved for storing the boot count, and care should be taken to not overwrite it inadvertently. In U-Boot, the boot count can be accessed with the 'fram' command.