Serial Port And Usb Interface - SimCom SIM808 Hardware Design

Coin-type rechargeable battery is recommended, such as XH414H-IV01E from Seiko can be used.
Typical charge-discharge curves for this battery are shown in the following figure.
Figure 21: Seiko XH414H-IV01E charge-discharge characteristic
4.6

Serial Port and USB Interface

SIM808 provides one unbalanced asynchronous serial port. The module is designed as a DCE (Data
Communication Equipment). The following figure shows the connection between module and client (DTE).
Table 10: Serial port and USB pin definition
Name
DTR
RI
DCD
Serial port
CTS
RTS
TXD
RXD
VBUS
USB
USB_DP
interface
USB_DM
Note: Hardware flow control is disabled by default. The AT command "AT+IFC=2,2" can enable hardware flow control .The AT
command "AT+IFC=0,0"can disable hardware flow control. For more details, please refer to document [1].
Table 11: Serial port characteristics
Symbol
V
IL
V
IH
V
OL
V
OH
SIM808_Hardware Design_V1.00
Pin number Function
9 Data terminal ready
10 Ring indicator
11 Data carrier detect
12 Clear to send
13 Request to send
14 Transmit data
15 Receive data
25 USB power supply
26 USB data line plus
27 USB data line minus
Min
0
2.5
0
2.7
Max
0.3
2.8
0.1
2.8
31
Smart Machine Smart Decision
Unit
V
V
V
V
2014.03.27