OCPRF100 MP Server System Technical Product Specification

Revision 1.0

8.2.7.3Fault LEDs

The hot-swap controller is responsible for turning the drive fault LEDs on or off according to the states specified via commands received through SAF-TE and the IPMB. The drive fault LEDs are yellow and serve to indicate failure status for each drive. The LEDs are physically located on the LVDS SCSI backplane, and are driven from the backplane.

During initialization, the microcontroller flashes the LEDs for 2 seconds to signal POST completion successfully.

8.2.8IPMB (I2C bus)

The Intelligent Platform Management Bus(IPMB) is a system-wide I2C server management bus. It provides a way for various system components to communicate independent of the other sys-

tem interfaces (e.g., the PCI bus or the processor/memory bus). The I2C bus controller is integrated into the microcontroller.

8.2.9Temperature Sensor

A Dallas* DS1621 temperature sensor device is connected to each microcontroller on a “private”

I2C bus. This device is used to monitor the drive bay temperature. The temperature may be read via SAF-TE and IPMB commands. In addition, settable temperature thresholds are provided via IPMB commands. The hot-swap controller (HSC) can be configured to issue an event message on the IPMB when the temperature threshold is crossed.

Microcontroller programming implements the private I2C connection by explicitly setting and clearing appropriate clock and data signals, to emulate an I2C-like interface to the sensor.

8.2.10Serial EEPROM

The AT24C02N* provides 256 bytes of nonvolatile storage. This is used to hold the serial num- ber, part number, and other field replaceable unit (FRU) inventory information and miscellaneous application code used by firmware about the backplane.

8.3Board Functions

This section describes functioning parts as required by the SCSI Accessed Fault-Tolerant Enclosures Interface Specification and SCSI Command Set For Enclosure Services Document Specification . In addition to these requirements, the board is capable of downloading code via IPMB to update the Flash executable code. The backplane functions begin at power up.

8.3.1Reset

8.3.1.1Cold Reset

At power up, all logic on the backplane is held in reset until the power supplies are stable. Two sources of power-good signaling are used. The first is the PWR_GOOD signal from the power

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