SimCom SIM800L - Serial Port and USB Interface

Smart Machine Smart Decision
SIM800L(MT6261)_Hardware Design_V1.01 28 2016-07-07
Note: The clock error becomes larger when VBAT is turned off and RTC circuit was supplied from the backup battery or the
external capacitor.
4.5. Serial Port and USB Interface
SIM800L default provides one unbalanced asynchronous serial ports. The module is designed as a DCE (Data
Communication Equipment). The following figure shows the connection between module and client (DTE).
Table 9: Serial port and USB pin definition
Note: Hardware flow control is disable by default. AT command “AT+IFC=2,2”can enable hardware flow control. AT command
“AT+IFC=0,0”can disable hardware flow control. For more details please refer to document [1].
Table 10: Serial port characteristics
Symbol Min Typ Max Unit
V
IL
-0.3 - 0.7 V
V
IH
2.1 - 3.1 V
V
OL
- - 0.4 V
V
OH
2.4
2.8
-
V
4.5.1 Function of Serial Port
Serial port:
 Full mode device.
 Contains data lines TXD and RXD, hardware flow control lines RTS and CTS, status lines DTR, DCD and
RI.
 Serial port can be used for CSD FAX, GPRS service and AT communication. It can also be used for
multiplexing function. For details about multiplexing function, please refer to table 11.
 Serial port supports the following baud rates:
1200, 2400, 4800, 9600, 19200, 38400, 57600,115200,230400 and 460800bps
 Autobauding only supports the following baud rates:
1200, 2400, 4800, 9600, 19200, 38400, 57600 and 115200bps
Pin name Pin number Function
Serial port
DTR 69 Data terminal ready
RI 68 Ring indicator
DCD 70 Data carrier detect
CTS
34
Request to send
RTS
33
Clear to send
TXD 32 Transmit data
RXD
31
Receive data
Debug port
VBUS 7 USB power supply
USB_DP 59 USB data line positive
USB_DN 19 USB data line negative
SIMCOM CONFIDENTIAL FILE