User's Manual

SIM900B EVB User Guide
SIM900B-EVB_UGD_V1.01 12 14.04.2010
3.5 RS232 Interface
Figure 8： Serial Port and Debug Port
Serial Port——MAIN Interface
Debug Port——DEBUG Interface
Main Interface:
Pin Signal I/O Description
1 DCD O Data carrier detection
2 TXD O Transmit data
3 RXD I Receive data
4 DTR I Data Terminal Ready
5 GND GND
7 RTS I Request to Send
8 CTS O Clear to Send
9 RI O Ring Indicator
Debug Interface:
Pin Signal I/O Description
2 DBG_TXD O Transmit data
3 DBG_RXD I Receive data
5 GND GND