Intel S5500HCVR Datasheet download pdf (Page 177)

Intel® Server Board S5520HC / S5500HCV TPS Appendix E: POST Code Diagnostic LED Decoder

Revision 1.2

Intel order number E39529-009

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Appendix E: POST Code Diagnostic LED Decoder

During the system boot process, the BIOS executes a number of platform configuration

processes, each of which is assigned a specific hex POST code number. As each configuration

routine is started, the BIOS displays the POST code to the POST Code Diagnostic LEDs on the

back edge of the server board. To assist in troubleshooting a system hang during the POST

process, you can use the Diagnostic LEDs to identify the last POST process executed.

Each POST code is represented by eight amber Diagnostic LEDs. The POST codes are divided

into two nibbles: an upper nibble and a lower nibble. The upper nibble bits are represented by

Diagnostic LED’s #4, #5, #6, and #7. The lower nibble bits are represented by Diagnostics

LED’s #0, #1, #2, and #3. If the bit is set in the upper and lower nibbles, the corresponding LED

lights up. If the bit is clear, the corresponding LED is off.

Diagnostic LED #7 is labeled “MSB” (Most Significant Bit), and Diagnostic LED #0 is labeled

“LSB” (Least Significant Bit).

A. Diagnostic LED #7 (MSB LED) E. Diagnostic LED #3

B. Diagnostic LED #6 F. Diagnostic LED #2

C. Diagnostic LED #5 G. Diagnostic LED #1

D. Diagnostic LED #4 H. Diagnostic LED #0 (LSB LED)

Figure 57. Diagnostic LED Placement Diagram

In the following example, the BIOS sends a value of EDh to the diagnostic LED decoder. The

LED’s are decoded as follows:

Table 83. POST Progress Code LED Example

Upper Nibble LED’s Lower Nibble LED’s

LED

LED’s

8h 4h 2h 1h 8h 4h 2h 1h

Status

ON ON ON ON ON ON OFF ON

1 1 1 0 1 1 0 1

Results

Eh Dh

1 2 ... 172 173 174 175 176 177 178 179 180 181 182 ... 191 192

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Intel S5500HCVR Datasheet Page 177