EFM8UB2 Datasheet, PDF (22/50 Pages) Silicon Laboratories – The EFM8UB2 highlighted features are listed below

6. Pin Definitions
6.1 EFM8UB2x-QFP48 Pin Definitions
EFM8UB2 Data Sheet
Pin Definitions
P0.5 1
P0.4 2
P0.3 3
P0.2 4
P0.1 5
P0.0 6
GND 7
D+ 8
D- 9
VDD 10
VREGIN 11
VBUS 12
48 Pin QFP
36 _P2.2
35 _P2.3
34 _P2.4
33 _P2.5
32 _P2.6
31 _P2.7
30 _P3.0
29 _P3.1
28 _P3.2
27 _P3.3
26 _P3.4
25 _P3.5
Figure 6.1. EFM8UB2x-QFP48 Pinout
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