SimCom SIM300D User Manual page 6

SIM300D EVB User Guide
Figure 2: EVB BOTTOM view
A: SIM300DTE with SIM300D module interface
B: SIM card interface
C: headset interface
D: Download switch, turn on or off download function
E: VBAT switch, switch the voltage source from the adaptor or external battery
F: VCHG ON/OFF control (shifter S3)
G: PWRKEY key, turn on or turn off SIM300D
H: main and debug serial port
I: MAIN serial port for downloading, AT command transmiting, data exchanging
J: DEBUG serial port
L: source adapter interface
M: light
N: buzzer
O: headphones interface
SIM300D-EVB_UGD_V1.01 Page 6 of 19