Functional Description
AM4011
Page 2 - 8
ID 1022-1626, Rev. 1.0
P R E L I M I N A R Y
How to Read the 8-Bit POST Code
Due to the fact that only 4 bits are available and 8 bits must be displayed, the User-Specific
LEDs are multiplexed.
The following is an example of the User-Specific LEDs’ operation if BIOS POST configuration
is enabled (see also Table 2-2, “User-Specific LED Function”).
Table 2-3:
POST Code Sequence
STATE
USER-SPECIFIC LEDs
0
All User-Specific LEDs are OFF; start of POST sequence
1
High nibble
2
Low nibble; state 2 is followed by state 0
Table 2-4:
POST Code Example
LED3
LED2
LED1
LED0
RESULT
HIGH NIBBLE
off (0)
on (1)
off (0)
off (0)
0x4
LOW NIBBLE
off (0)
off (0)
off (0)
on (1)
0x1
POST CODE
0x41
Note ...
Under normal operating conditions, the User-Specific LEDs should not remain lit
during boot-up. They are intended to be used only for debug purposes. In the
event that a User-Specific LED lights up during boot-up and the AM4011 does
not boot, please contact the Kontron’s Technical Support.
If all User-Specific LEDs flash red on and off at regular intervals, they indicate
that the processor junction temperature has reached a level beyond which per-
manent silicon damage may occur. Once activated, the overtemperature event
remains latched until a cold restart of the AM4011 is undertaken (all power off
and then on again).
