Aaeon SBC-357 Manual page 33

The CPU card has its own buzzer. You can disable the internal
buzzer and connect an external speaker to EXT SPK. Enabling the
external speaker automatically disables the internal buzzer.
Buzzer*
1 2 3 4 5
* default
Pin Function
1 Vcc
2 N.C.
3 Buzzer in
4 Speaker output
5 Speaker output
You can select the LCD control signals by setting JP1. The
following charts show the available options.
SHF CLK from C&T65545*
1 2 3
* default
External Speaker
1 2 3 4 5
ASHF CLK from SHF CLK
1 2 3
Chapter 2 Hardware Configuration 25