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Squadrons H: Method to Lamp Test LEDs in Standby mode with limited current draw

IP.com Disclosure Number: IPCOM000033914D
Original Publication Date: 2005-Jan-04
Included in the Prior Art Database: 2005-Jan-04
Document File: 2 page(s) / 87K

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Disclosed is a method to perform a validation of LED functionality in a computer system at standby mode of operation when the power supplies are current limited. In computer systems where LEDs are employed to assist with service, a Lamp Test mode is required to light all of the LEDs for visual inspection to determine that none of the LEDs has failed. This function is used not only in Service in the field, but in manufacturing to verify that the LEDs are functional prior to shipping the system. The Lamp test of the lightstrip card employed in certain high end IBM Unix servers would trip over-current sensors on power supplies if an attempt to light all LEDs is made to verify LED functionality because of the current draw of the LEDs. Therefore, a new Lamp Test design is described which will provide the capability to visually inspect all of the LEDs to insure that they are functional but will stay within the limits of the current supplying capability of the power subsystem.

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Squadrons H: Method to Lamp Test LEDs in Standby mode with limited current draw

When the lamp test option is selected, the firmware in the microcontroller controlling the LEDs on the lightstrip will light a row of LED's for a set period of time (for example 5 seconds), turn them off for another period of time (say 2 seconds) and then switch to the next row of LEDs on the LightStrip card and light them for 5 seconds, etc. repeating the process rippling through the rows of LEDs on the LightStrip card until the lamp test for this LightStrip card is completed. Refer to the drawings below for representative samples of the type of Lightstrips utilized on high-end Unix systems that this description applies to.

High-end Unix System CEC Front LED Panel

P2 P3

   C13 C12 C11 C10 C9 C8 C7 C6 C5 C4 C3 C2 C1

P4 P5



   C19 C18 C17 C16 C15 C14 C25

   C24 C23 C22 C21 C20


Sys. Atn.





High-end Unix System CEC Back LED Panel



Sys. Atn.






E1 E2 E3 E6

E4 E5 E12

E7 E8 E9 E10 E11

Each Lightstrip panel represents a specific set of FRUs in the CEC of a High-end Unix system. Each LED is associated with a specific FRU within that set of FRUs represented by the lightstrip. For example, the Px LEDs represent system planars, the Cx represent specific cards on those planars, Ax represents Air Moving Devices used for cooling and Ex represent power components.

This limits the current to an acceptable level and provides an interface for the manufacturer or servicer to verify correct operation of all of the LEDs on the lightstrip


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