RIM 1902G Integrator Manual page 54

Chapter 6: Interface specification
Pin Label
11 ONI On Indicate
This line is a digital output from the radio that indicates that the radio is on and operational.
This line can be used by a computing device to qualify the handshaking outputs on the serial
interface. If CTS is low, and ONI is high, the unit is ready to receive data, but if CTS is low and
ONI is low, the radio modem is not ready to receive data because it is off.
When ONI is low, all inputs to the radio modem should be low or disconnected. Otherwise,
power is consumed and wasted.
12 TRI Transmit Indicate
The active (radio transmitting) state of this line is high.
This output from the radio modem is asserted while the radio is transmitting a packet to the
network base station. TRI has a built-in current limiter that enables it to directly drive an LED ,
which provides real-time visual feedback that the radio is transmitting packets. If this is not
necessary, you can leave the line disconnected.
This line supplies 3 mA to a standard LED, and is short-circuit protected. This line is low when
the radio modem is off.
13 TX2 Secondary Transmit
This line is an input to the radio modem (for RIM internal use only).
14 ~RI ~Ring Indicate
This line is an output from the radio modem. It indicates an incoming call on the serial line.
When ~DTR is not asserted (high), the radio modem asserts ~RI (low) to indicate that it has
data waiting for the computing device. The radio modem does not transfer the data until
~DTR is asserted (low). This line can be used to wake up a suspended computing device when
the radio modem needs to communicate with it. If ~DTR is already asserted (low) when the
radio modem has data to send the computing device, ~RI is not asserted.
15 ~CTS ~Clear To Send
This line is a digital output from the radio modem to the computing device. The active (clear
to send) state of this line is low.
When asserted low by the radio modem, this line indicates that it is ready to receive data from
the computing device. While this line is high, any data sent from the computing device to the
RIM 1902G or RIM 1802G may be lost. This line is a flow control mechanism that is normally
reacted to by the UART in your serial communication system. If you do not plan to use it, leave
~CTS disconnected.
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Description
RIM OEM Radio Modem for GSM/GPRS Wireless Networks