'1' = LED on

Sel #  D C B A
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1      0 0 0 0
2      0 0 0 1
3      0 0 1 0
4      0 0 1 1
5      0 1 0 0
6      0 1 0 1
7      0 1 1 0
8      0 1 1 1
9      1 0 0 0
10     1 0 0 1
11     1 0 1 0
12     1 0 1 1
13     1 1 0 0
14     1 1 0 1
15     1 1 1 0
16     1 1 1 1
--------------