Serial interface specification: Detailed pin description
Integrator’s Guide – RIM 801D OEM Radio Modem
22
simply be left disconnected. This line has a built in current limit that allows
it to drive an LED directly as visual feedback for a user.
This line will supply 3 mA to a standard LED, and is short-circuit protected.
This line is low when the Radio is off.
ONI
ON Indication is an output from the radio that indicates when the radio is
on and operational. This line should be used by a host system to qualify the
handshaking outputs on the serial interface. If CTS is low, and ONI is high,
then the unit is ready to receive data, but if CTS is low and ONI is low, then
the radio is not ready to receive data because it is off.
When ONI is low, all inputs to the radio should be held low or disconnected
to assure the unit power consumption is minimized.
ONI has an output impedance of 1 k
Ω
.
TURNON
This input turns on the radio unit – a TTL and CMOS compatible signal.
This pin’s electrical characteristics are different from the others, as shown in
the table below.
Input High Voltage
2.5 Volts Min.
Input Low Voltage
0.8 Volts Max.
Input Leakage Current High
500
µ
A Max.
Input Leakage Current Low
-50
µ
A Max.
Due to the higher current requirements of this pin, a direct drive CMOS or
TTL output must be used. An open-collector output could also be used,
provided it is pulled up by a 10 k
Ω
resistor or smaller.
