Function Of Serial Port & Debug Port Supporting - SimCom SIM900D Hardware Design

SIM900D Hardware Design
DBG_RXD: Receive data from the TXD signal line of the DTE
The logic levels are described in following table.
Table12: Logic levels of the serial port and debug port
Parameter
V
IL
V
IH
V
OL
V
OH
MODULE (DCE)
3.9.1 Function of serial port & debug port supporting
Serial port
Modem device.
Contains data lines TXD and RXD, State lines RTS and CTS, Control lines DTR, DCD and RI.
Serial port can be used for CSD FAX, GPRS service and send AT command of controlling module. Also
serial port can be used for multiplexing function. SIM900D supports only basic mode of multiplexing so far.
Serial port supports the communication rates as following:
1200,2400, 4800, 9600, 19200, 38400, 57600, 115200bps
Autobauding supports baud rates as following:
1200, 2400, 4800, 9600, 19200, 38400, and 57600bps, the default setting is autobauding.
Autobauding allows the GSM engine to automatically detect the baud rate configured in the host application. The
serial port of the GSM engine supports autobauding for the following baud rates: 1200, 2400, 4800, 9600, 19200,
SIM900D_Hardware Design_V1.04
Min
0
2.4
0
2.7
Serial port
TXD
RXD
RTS
CTS
DTR
DCD
RI
Debug port
DBG_TX
DBG_RX
Figure18: Connection of the serial interfaces
Max
0.4
3
0.1
3
CUSTOMER (DTE)
Serial port1
TXD
RXD
RTS
CTS
DTR
DCD
RING
Serial port2
TXD
RXD
37
Unit
V
V
V
V
2010.10.09