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Board is equipped with
8Mhz crystal oscillator
circuit that provides stable clock signal to the
microcontroller OSC pins. Internally, this signal is used
for creating the clock necessary for the operation of
microcontroller.
5. Crystal oscillator
Figure 5-1:
8MHz crystal oscillator
VCC-3.3
C2
22pF
C1
22pF
X1
8MHz
AVCC
30
29
28
27
34
33
58
57
56
55
54
53
52
46
36
35
42
43
44
45
37
50
9
48
49
11
12
32
72
69
68
67
66
65
64
63
4
3
78
77
24
23
18
17
16
15
14
13
5
6
7
8
10
79
80
1
2
22
21
20
19
62
61
60
59
38
39
40
41
47
71
31
51
70
26
25
76
75
74
73
LM3S9B95
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
PA7
PA6
ERBIAS
VDD
PF4
PF5
PE5
PE4
LDO
VDD
GND
VDD
PB1/USB0VBUS
VDD
VDD
TXOP
PJ4
PJ5
PJ6
PJ7
GND
TXON
PB5
PB6
PB7
VDD
VDDC
PJ1
PH2
PH3
GNDA
VDDA
PD5
PD4
PE3
PE2
GND
PB4
PD2
PA2
PC6
PC7
GND
VDD
PG0
PG1
USB0DP
USB0DM
NC
PB3/I2C0SDA
PJ0
PD1
PD0
VDDC
PD6
PD7
PE7
PE6
PA1
PA0
PC4
PC5
OSC1
PJ3
PB0/USB0ID
PF2
PF0
OSC0
GND
PJ2
RXIN
MDIO
PF1
PH0
XTALNPHY
XTALPPHY
PH7
PG7
RXIP
PF3
RST
PH1
PA5
PA4
PA3
PD3
GND
PH6
PH5
PB2/I2C0SCL
PC2
PH4
USB0BIAS
PE0
PE1
PC3
PC1
PC0
VDD
GND
U1
OSC0
OSC1
R61
9K1
E9
10uF
VCORE
VCORE
Figure 5-2:
Crystal oscillator schematics
