Appendix E: Post Code Diagnostic Led Decoder; Figure 66. Diagnostic Led Placement Diagram; Table 125. Post Progress Code Led Example - Intel SC5650HCBRP Product Specification

Appendix E: POST Code Diagnostic LED Decoder

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)
B. Diagnostic LED #6
C. Diagnostic LED #5
D. Diagnostic LED #4
In the following example, the BIOS sends a value of EDh to the diagnostic LED decoder. The
LED's are decoded as follows:
LED
LED's
#7
8h
Status ON
1
Results
200

Figure 66. Diagnostic LED Placement Diagram

Table 125. POST Progress Code LED Example

Upper Nibble LED's
LED LED
#6 #5
4h 2h
ON ON
1 1
Eh
Intel order number E81443-002
Intel® Server System SC5650HCBRP TPS
E. Diagnostic LED #3
F. Diagnostic LED #2
G. Diagnostic LED #1
H. Diagnostic LED #0 (LSB LED)
LED LED
#4 #3
1h 8h
ON ON
0 1
Lower Nibble LED's
LED LED
#2 #1
4h 2h
ON OFF
1 0
Dh
Revision 1.2
LED
#0
1h
ON
1