Serial Port And Usb Interface - SimCom SIM800 Hardware Design


Non-chargeable battery backup
Non-chargeable
Backup Battery

Rechargeable battery backup
Rechargeable
Backup Battery
Note: RTC can not be directly connected to the VBAT, VRTC refer to table 44.

4.5. Serial Port and USB Interface

SIM800 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 8: Serial port and USB pin definition
Name
DTR
RI
DCD
Serial Port CTS
RTS
TXD
RXD
USB_VBUS
USB Interface USB_DP
USB_DN
SIM800_Hardware Design_V1.10
Figure 17: RTC supply from non-chargeable battery
VRTC
Figure 18: RTC supply from rechargeable battery
Pin number
3
4
5
7
8
9
10
24
27
28
28
Module
VRTC
1.5K
Module
1.5K
Function
Data terminal ready
Ring indicator
Data carrier detect
Clear to send
Request to send
Transmit data
Receive data
USB power supply
USB data line positive
USB data line negative
Smart Machine Smart Decision
RTC
Core
RTC
Core
2018-08-13