Debugging Features - Kontron AdvancedTCA AT8001 User Manual

2.17 Debugging Features

2.17.1 POST Code Blinker / IDE Activity
The postcode blinker circuit uses a blinking sequence to display the current POST (Power On Self
Test) code value on faceplate. This functionality is shared with the hard drive activity LED. This
sequence restarts every time the POST codes value changes. Because POST codes changes all the
time during a normal boot process, the blinker does not have enough time to complete its sequence
and the debug LED blinks meaninglessly.
If the boot process succeeds, the POST code value has no interest and the BIOS will disable the post
code blinker before the operating system launches.
If the boot sequence fails or the CPU hangs, the postcode blinker remains operational and repeats
indefinitely the last postcode blink sequence defined below.
1. Blink simultaneously AMBER and GREEN one time: start of the sequence.
2. Blink AMBER "A" times while GREEN stays off. "A" range from 0 to 15.
3. Blink GREEN "G" times while AMBER stays off. "G" range from 0 to 15.
4. Repeat the sequence. (See step 1.)
"A" is the first (most significant) digit of the post code value in hexadecimal; while "G" is the
second digit (i.e. post code value is AGh). Some examples are shown in the following figure.
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AT8001 User's Guide