SimCom SIM300 - Accessories; 2 EVB and Accessory Equipment

D: Download switch, turn on or off download function
E: VBAT switch, switch the voltage source from the adaptor or external battery
F: PWRKEY key, turn on or turn off SIM300
G: buzzer
H: expand port, such as keypad port, main and debug serial port, display port
I: MAIN serial port for downloading, AT command transmitting, data exchanging
J: DEBUG serial port
K: hole for fixing the antenna
L: source adapter interface
M: light
N: hole for fixing the SIM300
O: headphones interface
1.2 accessories
A: antenna
B: antenna transmit line
C: headset
D: 5V DC source adapter
E: serial port line
2 EVB and accessory equipment
At normal circumstance, the EVB and its accessory are equipped as the nether figure：