Schematics

1 2 3 4
A
B
C
D
4321
D
C
B
A
VBAT
S1
POWER
PWRKEY
+5V
D2
RED
D1
BLUE
MICIN
BAT+1
B+
BAT-1
B-
DACL
+5V
VBAT
VDDIO
C1 NC
C2 105
MICIN
Y1
26MHZ
PB3
PWRKEY
VDDIO
5
VBAT
6
VDDBT
8
AGND
2
DGND
7
BT_ANT
10
BT_OSCI
11
BT_OSCO
12
PE7/ADC9
1
VUSB
4
VCMBUF
15
PWRKEY
9
ADC10/MICL/PF2
14
ADC5/PB3
13
PE0
3
DACL
16
U1
AB5377A2 - SOP16 150mil
PE7
P3
L+
P4
L-
DACL
DACL#
DACL#
PE7
VDDIO
+
MIC1
P3
P4
+5V
GND
PB3
2
2
3
3
1
1
R1
NC
R2
NC
ANT