Specifications

SAS Riser QSSC-S4R Technical Product Specification
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Figure 20. SAS Riser Board System Block Diagram
7.2.1 I²C Interface
The SAS Riser board contains three I2C busses that come from the SAS2108 ROC Controller. The SAS2108 I2C bus
0 is connected to a temperature sensor, the memory SPD SEEPROM, a 3-pin header, a PCA9551 or equivalent I2C
LED driver and a PCA9546A or equivalent 4 port I2C switch. Connected to the I2C switch are the BBU module,
SFF8448 I2C enclosure management, and a stand-alone enclosure management header. The SAS2108 I2C bus 1 is
connected to the PCI-Express edge card connector using zero ohm resistors so that these can be depopulated for
testing purposes. The SAS2108 I2C bus for SBL support is connected to the SBL SEEPROM.
7.2.2 Host Interface
The SAS Riser board interfaces with the host system through a standard card edge x8 PCI-Express 2.0 bus connection
as defined in the PCI-Express specification. This interface also provides power to the board and an I2C interface
connected to I2C bus one for IPMI.
7.2.3 Internal SAS Interface
The 6Gb/s SAS interface allows the SAS Riser to be connected to SAS or SATA drives through the Hot-swap
Backplane by using two mini SAS cables (with SAS SGPIO). The SAS interface is divided into two Mini SAS 4i
connectors (SFF-8087), in which each (JT6 and JT7, as shown in the figure below) contains four SAS ports.