WIT910
4. MODEM INTERFACE
Electrical connection to the WIT910 is made through a 16-pin male header on the modem
module. The signals are 3.3-volt signals and form an RS-232 style asynchronous serial
interface. The table below provides the connector pinout.
Pin Signal Type Description
1
GND
-
Signal and chassis ground
2
TXD
Input
Transmit data. Input for serial data to be transmitted. In Control
Mode also used to transmit modem commands to the modem.
3
RXD
Output
Receive data. Output for received serial data. In Control Mode,
also carries receive modem status from the modem.
4
Input
Configuration selector. Used to switch between Control and Data
Modes. Normally, CFG will be set for Data Mode. An internal 10K
pull-up enables Data Mode if this signal is left unconnected.
Control Mode is also accessible by transmitting an escape
sequence immediately after wake up or power up.
(0v)
1 = Control Mode
(3.3v) 0 = Data Mode
5
Input
Request to send. Gates the flow of receive data from the radio to
the user on or off. In normal operation this signal should be
asserted. When negated, the WIT2450 buffers receive data until
RTS is asserted.
(0v)
1 = Receive data (RxD) enabled
(3.3v) 0 = Receive data (RxD) disabled.
6
DTR
Input
Sleeps/wakes radio transceiver. In sleep mode all radio functions
are disabled. At wake up, any user programmed configuration
settings are refreshed from non-volatile memory, clearing any
temporary settings that may have been set.
(3.3v) 1 = Sleep Radio
(0v)
0 = Wake Radio
7
Output
Data carrier detect. For remotes, indicates the remote has
successfully acquired the hopping pattern of the base station.
(0v)
1 = Carrier detected (synchronized)
(3.3v) 0 = No carrier detected (not synchronized)
8
Output
Clear to send. Used to control transmit flow from the user to the
radio.
(0v)
1 = Transmit buffer not full, continue transmitting
(3.3v) 0 = Transmit buffer full, stop transmitting
9
RSSI
Output
Received Signal Strength Indicator (analog signal)
10 Input
Resets
the
radio.
11-15
-
-
Reserved for future use. Do not connect.
16
VCC
-
Positive supply. Min 3.3 v, 5.0 v nominal, 10.0 v max.
CFG
RTS
DCD
CTS
Reset
©2010-2015 by Murata Electronics N.A., Inc.
WIT910 Integration guide (R) 05/14/15
16 of 49
www.murata.com