11990-704/705/706/707 (2-Slot ATCA Shelf)
ATCA Backplane
8
R1.2, March 2018
3.3 Shelf FRU SEEPROM
2 Shelf FRU SEEPROMS are located on the Backplane. The hardware address for these
SEEPROMs is 0xA4.
The SEEPROMs are the repository of the shelf specific information capabilities of the system
and other user configurable options. The SEEPROMs contain the list of which slots are
connected together, how the update channels are routed, how many slots are in the system,
what the maximum power is to each slot, serial number of the shelf, backplane topology, etc.
The Shelf Manager uses this information to provide functions such as electronic keying,
controlling the power state of the system, etc.
The Shelf allows for 2 methods to access the chassis FRU data:
• An I2C connection from each Shelf Manager directly to the SEEPROMs on the backplane.
• SEEPROMs on the backplane exposed as a FRU of the Fan Tray.
3.4 Logic Ground
Figure 3: Logic Ground
The ATCA backplane provides a mechanism to connect Logic Ground and Shelf Ground. The
backplane fixing screw (arrow) is isolated by a plastic washer. To connect Logic Ground and
Shelf Ground remove the screw, remove the plastic washer and re-install the screw.
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The default factory assembly isolates Logic Ground from Shelf Ground.
