5
User I/O Connector
The User I/O is via a female 16-pin .100” header connector.
The following pins are defined.
Front-view of 16-pin header connector on modem module
Pin #
Name
Dir
Function
5.1.1.1.1 Level / Specification
1, 2
Power
In/out
DC power
User may supply the main DC power to the
modem on this pin. 5.0 – 8.0V DC in.
3
/Sleep
In
Puts modem into SLEEP
mode.
Leave open if unused. Pull low to enter sleep
mode. Internally pulled up to 3.3V.
4
RxD
In
Receive serial data
Data in. 3.3V logic levels.
5
TxD
Out
Transmit serial data
Data out. 3.3V logic levels.
6
RTS
In
Request to send
Used to stop/start the flow of data coming out
of the modem TxD pin. 0 = OK to send, 1 =
don’t send. Connect to GND, pin 9&10 if
unused.
7
CTS
Out
Clear to send
Used to stop the flow of data coming into the
RXD pin. 0 = OK to send, 1 = don’t send.
Open Drain output, with 10K pull-up to 3.3V.
8
CD
Out
Carrier detect
If enabled, indicates presence of carrier. 0
means carrier is present. If disabled, it is
asserted (0) whenever the modem is
operational, and not in the configuration
mode. It will be a 1 when the modem is in the
configuration mode.
11
Audio
Out
Audio output.
For test purposed. Leave open circuit.
9, 10
GND
Ground connection
Signal and power ground
12
/config
In
Puts modem into the
configuration mode.
Leave open circuit if unused. Pull low to put
modem into the configuration mode.
13
ENABLE
In
On/Off control line.
Leave open or pull > 2V to enable the
modem. Pull low to turn modem power off.
15
IO3
In/Out
Special function digital I/O
Do not connect. Digital I/O for OEM
applications. In standard version, this signal
is the same one the drives the TX LED on the
module.
16
IO4
In/Out
Special function digital I/O
Do not connect. Digital I/O for OEM
applications. In standard version, this signal
is the same one the drives the RX LED on the
module.
14
Reset
In
Reset input
Do no connect.
At a minimum, the user must apply DC power to pins 1&2, ground pins 6, 9, 10,
and connect data in and data out to pins 4&5. All other pins may be left
disconnected.
