GSM/GPRS Module
M85 Hardware Design
M85_Hardware_Design Confidential / Released 37 / 92
RXD: Receive data from TXD of DTE.
RTS: Request to send.
CTS: Clear to send.
DTR: DTE is ready and inform DCE (this pin can wake the module up).
RI: Ring indicator (when the call, SMS, data of the module are coming, the module will output signal
to inform DTE).
DCD: Data carrier detection (the validity of this pin demonstrates the communication link is set up).
The module disables hardware flow control by default. When hardware flow control is required, RTS and
CTS should be connected to the host. AT command ―AT+IFC=2,2‖ is used to enable hardware flow
control. AT command ―AT+IFC=0,0‖ is used to disable the hardware flow control. For more details, please
refer to the
document [1]
.
The Debug Port
DBG_TXD: Send data to the COM port of computer.
DBG_RXD: Receive data from the COM port of computer.
The Auxiliary UART Port
TXD_AUX: Send data to the RXD of DTE.
RXD_AUX: Receive data from the TXD of DTE.
The logic levels are described in the following table.
Table 7: Logic Levels of the UART Interface
Table 8: Pin Definition of the UART Interfaces
Parameter
Min
Max
Unit
V
IL
0
0.25×VDD_EXT
V
V
IH
0.75×VDD_EXT
V0.3
V
VOL
0
0.15×VDD_EXT
V
VOH
0.85×VDD_EXT
VDD_EXT
V
Interface
Pin No.
Pin Name
Description
Debug Port
43
DBG_RXD
Receive data
NOTE
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