WIT2492
RFM/Cirronet Inc
2
WIT2492
4. MODEM INTERFACE
Electrical connection to the WIT2492 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 WIT2492 buffers receive data until RTS is asserted.
(0v)
1 = Receive data (RxD) enabled
(3.3v)
0 = Receive data (RxD) disabled.
6
SLEEP
Input
Sleeps/wakes radio transceiver. In sleep mode all radio functions are
disabled consuming less than 50µA. 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
-
-
Reserved for future use. Do not connect.
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.
RTS
DCD
CTS
CFG
Reset
