5. ELECTRICAL DESCRIPTION
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LZ T 123 7 605 P1C
driven by low side switches return to open circuit when deactivated. This
allows the external application hardware to determine the desired logic
voltage levels with the appropriate pull-up.
The output drivers are low side switches which short the pin to GND if
they are activated.
Note!
As an alternative configuration signals OUT-3 and OUT-4 can be used to
support a second RS232 serial interface as RD-2 and CTS-2. Further
information is given below.
+4.8V Output Supply
Pin 9
There is a voltage regulator implemented inside the module that is capable
of supplying an external voltage source of +4.8V with a maximum current
of 75 mA.
The voltage source can be switched on/off with the DAC signal of the
internal Radio Device GSM engine.
By default the voltage source is switched on. A high level of 2.75V at the
DAC output of the Radio Device GSM engine will switch the voltage
source off.
Note!
The +4.8V source may be switched on/off via an embedded or external
application and so may be used as an optional digital output with levels of
+4.8V and open circuit.
5.2.6 Second RS232 Serial Interface
IN-3 and OUT-3 can be automatically reconfigured as signals TD-2 and
RD-2, of a second serial interface, by enabling UART3 of the internal
Radio Device. UART 3 may be enabled using AT command or intrinsic
function.
In addition, IN-2 and OUT-4 can be automatically reconfigured as signals
RTS-2 and CTS-2 of the second serial interface by enabling hardware flow
control for UART3 on the internal Radio Device. Hardware flow control
can be enabled using intrinsic function only.
Note!
The signal level thresholds for each of the digital inputs of the second serial
interface are: 3V<V
IH
<32V and V
IL
< 2.8V.
An external RS232 transceiver component may be used to convert the serial
interface to standard RS232 electrical levels. The Control Terminal's +4.8
V output can be used to provide power for the transceiver.