GE865 Hardware User Guide
1vv0300799 Rev.17– 2017-05-11
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved
page 45 of 75
RS232
Pin
Number
Signal
GE865
Pad Number
Name
Usage
1
DCD - dcd_uart
B5
Data Carrier Detect
Output from the GE865 that indicates the
carrier presence
2
RXD -
tx_uart
A4
Transmit line *see Note
Output transmit line of GE865 UART
3
TXD -
rx_uart
A3
Receive line *see Note
Input receive of the GE865 UART
4
DTR - dtr_uart
B3
Data Terminal Ready
Input to the GE865 that controls the DTE
READY condition
5
GND
C2, C7, E5,
E7, G1, G3,
G4, G5, H3,
H6
Ground
ground
6
DSR - dsr_uart
B2
Data Set Ready
Output from the GE865 that indicates the
module is ready
7
RTS -rts_uart
A1
Request to Send
Input to the GE865 that controls the
Hardware flow control
8
CTS - cts_uart
A2
Clear to Send
Output from the GE865 that controls the
Hardware flow control
9
RI - ri_uart
B4
Ring Indicator
Output from the GE865 that indicates the
incoming call condition
NOTE:
According to V.24, RX/TX signal names are referred to the application side, therefore on the
GE865 side these signal are on the opposite direction: TXD on the application side will be
connected to the receive line (here named TXD/ rx_uart ) of the GE865 serial port and
viceversa for RX.
NOTE:
For a minimum implementation, only the TXD and RXD lines can be connected, the other lines
can be left open provided a software flow control is implemented.
NOTE:
In order to avoid a back powering effect it is recommended to avoid having any HIGH logic
level signal applied to the digital pins of the GE865 when the module is powered off or during
an ON/OFF transition.
9.2.
RS232 level translation
In order to interface the GE865 with a PC com port or a RS232 (EIA/TIA-232) application a
level translator is required. This level translator must:
