Serial Port And Usb Interface; Function Of Serial Port - SIM Tech SIMCom SIM800C Hardware Design

4.5. Serial Port and USB Interface

SIM800C 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 8: Serial port and USB pin definition
Pin name
UART1_DTR
UART1_RI
UART1_DCD
UART1_CTS
Serial port UART1_RTS
UART1_TXD
UART1_RXD
UART2_TXD
UART2_RXD
USB_VBUS
Debug port USB_DP
USB_DN
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 9: Serial port characteristics
Symbol
V
IL
V
IH
V
OL
V
OH
SIM800C module can support dual serial port function, that need execute AT command "AT+CMNRP=1"first.
Dual serial port including one full modem serial port and one three-wire serial port, pin definition is different with
standard definition of the Figure 2: Pin assignment (Top view) and Table 5: Pin description. For more details
please refer to Document [2].
4.5.1

Function of Serial Port

Serial port:

Full mode device.

Contains data lines UART1_TXD and UART1_RXD, hardware flow control lines UART1_RTS and
UART1_CTS, status lines UART1_DTR, UART1_DCD and UART1_RI.
SIM800C_Hardware_Design_V1.00
Pin number Function
6 Data terminal ready
7 Ring indicator
5 Data carrier detect
4 Request to send
3 Clear to send
1 Transmit data
2 Receive data
22 Transmit data
23 Receive data
24 USB power supply
25
26
Min
-0.3
2.1
-
2.4
Max
0.7
3.1
0.4
-
25
Smart Machine Smart Decision
Unit
V
V
V
V
2014-10-30