User's Manual

CL865-DUAL Hardware User Guide
1vv0301104 Rev.1 – 2014-03-07
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights
Reserved. Page 39 of 70
Mod. 0805 2011-07 Rev.2
9.1. Modem Serial Port 1
The serial port 1 on the CL865 is a +1.8V UART with all 7 RS232 signals.
It differs from the PC-RS232 in the signal polarity (RS232 is reversed) and levels.
RS232
Pin #
Signal
CL865
Pin No.
Function
Usage
1
C109/DCD
1
Data Carrier Detect
Output from the CL865 that
indicates the carrier presence
2
C104/RXD
8
Transmit line *see
Note
Output transmit line of the
CL865 UART
3
C103/TXD
7
Receive line *see
Note
Input receive of the CL865
UART
4
C108/DTR
4
Data Terminal Ready
Input to the CL865 that controls
the DTE READY condition
5
GND
-
-
GND
6
C107/DSR
3
Data Set Ready
Output from the CL865 that
indicates the module is ready
7
C106/CTS
6
Request to Send
Output from the CL865 that
controls the hardware flow
control
8
C105/RTS
5
Clear to Send
Input to the CL865 that controls
the hardware flow control
9
C125/RING
2
Ring Indicator
Output from the CL865 that
indicates the incoming call
condition
The following table shows the typical value(pulled inside the baseband chipset) and status for
input lines in all module states:
Signal/State
OFF
RESET
ON
Powersaving
PU tied to
TXD
unknown
Pull Down
(21K~210K)
Pull Up
(39K~390K)
Pull Up
(39K~390K)
1.8V
RTS
Pull Down
(21K~210K)
DTR
Pull Up
(39K~390K)
NOTE:
According to V.24, RX/TX signal names are referred to the application side. Therefore, on the
CL865 side these signals are on the opposite direction:
TXD on the application side will be connected to the receive line (here named C103/TXD)
RXD in the application side will be connected to the transmit line (here named C104/RXD)