Serial Port And Usb Interface - SimCom SIM800C Hardware Design

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Rechargeable battery backup
Note: When shut off VBAT and power on VRTC only, the clock error becomes larger.

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 disabled by default. AT command "AT+IFC=2, 2"can enable hardware flow
SIM800C_Hardware_Design_V1.02
N on-chargeabl e
B ackup B at t ery
Figure 16: RTC supply from non-chargeable battery
R echargeabl e
B ackup B at t ery
Figure 17: RTC supply from rechargeable battery
Pin number Function
6 Data terminal ready
7 Ring indicator
5 Data carrier detect
4 Clear to send
3 Request to send
1 Transmit data
2 Receive data
22 Transmit data
23 Receive data
24 USB power supply
25 D+ data input/output
26 D- data input/output
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2015-4-27