User's Manual

CE910 Family Hardware User Guide
1vv0301010 Rev.11 – 2015-10-27
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 43 of 75
8.1. Modem Serial Port 1
The serial port 1 on the CE910 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
CE910
Pad No.
Function
Usage
1
C109/DCD
N14
Data Carrier Detect
Output from the CE910 that
indicates the carrier presence
2
C104/RXD
M15
Transmit line *see Note
Output transmit line of the CE910
UART
3
C103/TXD
N15
Receive line *see Note
Input receive of the CE910 UART
4
C108/DTR
M14
Data Terminal Ready
Input to the CE910 that controls
the DTE READY condition
5
GND
-
-
GND
6
C107/DSR
P14
Data Set Ready
Output from the CE910 that
indicates the module is ready
7
C106/CTS
P15
Clear to Send
Output from the CE910 that
controls the hardware flow control
8
C105/RTS
L14
Request to Send
Input to the CE910 that controls
the hardware flow control
9
C125/RI
R14
Ring Indicator
Output from the CE910 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 CE910
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)