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Board is equipped with
8MHz crystal oscillator
(X1)
circuit that provides external clock waveform
to the microcontroller CLKO and CLKI pins. This base
frequency is suitable for further clock multipliers and
ideal for generation of necessary USB clock, which ensures
proper operation of bootloader and your custom USB-based
applications. Board also contains
32.768kHz Crystal oscillator
(X3)
which provides external clock for internal
RTCC
module.
5. Crystal oscillator
Figure 5-1:
External crystal
oscillator (X1)
30
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34
33
46
36
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42
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37
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32
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26
9
11
12
4
3
24
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13
5
6
7
8
10
1
2
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21
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25
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10
0
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72
69
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51
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73
VCC-3.3
VREF-1.8
C30
22pF
C31
22pF
X3
32.768KHz
C2
22pF
C1
22pF
X1
8MHz
E9
10uF
CLKO
CLKI
SOSCO
SOSCI
PIC24EP512GU810
R
B1
1
R
B1
0
R
B
9
R
B8
R
B
13
R
B1
2
RE7
RC1
RC2
RC3
ASDA1/RA15
D+/RG2
R
B1
5
R
B1
4
RF8
Vbus
Vusb
D-/RG3
G
N
D
VC
C
R
A
6
R
G
0
R
G
1
R
E0
R
F1
R
F0
R
D
7
R
D
6
RE6
RE5
R
E2
R
G
13
R
G
12
R
G
14
R
E1
R
A
7
RG8/SDO2
R
A
9/
Vr
ef
-
RB1
RB2
RB3
RB4
RB5
RE9
RD9
RD8
RF2
USBID/RF3
GND
RG7/SDI2
RG6/SCK2
R
A
1
R
E3
R
E4
RG15
VDD
R
B7
/P
G
ED
1
R
B6
/P
G
EC
1
RB0
R
F4
R
F5
ASCL1/RA14
RA5
R
D
14
R
D
15
ASCL2/RA2
R
F1
3
VC
C
ASDA2/RA3
VCC
EN
VR
EG
RE8
RA0
VCC
G
N
D
R
F1
2
RA4
GND
VC
A
P
A
G
N
D
A
VC
C
R
A
10
/V
re
f+
MCLR
RC4
CLKI/RC12
CLKO/RC15
RD10
R
D
3
R
D
1
SOSCI/RC13
SOSCO/RC14
GND
R
D
2
R
D
12
R
D
13
R
D
4
R
D
5
RG9
RD11
RD0
U1
C5
100nF
C6
100nF
C7
100nF
E8
10uF
VCC-3.3 VCC-3.3 VCC-3.3
VCC-3.3
C8
100nF
VCC-3.3
C34
100nF
VCC-3.3
decoupling capacitors
The use of crystal in all other schematics is implied even if it is purposely
left out because of the schematics clarity.
NOTE :
Figure 5-2:
Crystal oscillator schematic
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