Section A.2 - Application Notes.Design Examples
Version 1.3 - 2009-12
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A.2.2 Serial Interface
The serial interface of the module is Logic Level logic levels and the module can be connected to
an external CPU (see section A.2.2.1).
An external driver is needed if the module should be on another physical interface like RS232
(see section A.2.2.2 - A.2.2.3).
CTS (Clear To Send) and RTS (Request To Send) are used for hardware flow control.
DSR (Data Set Ready) can be used to make a connect attempt. See the Serial Port Adapter AT
commands specification.
DTR (Data Terminal Ready) can be used to detect if the module is up and running and ready to
receive data.
Note! The module must be configured to flow control none if hardware flow control is
not used, see the Serial Port Adapter AT Commands specification.
A.2.2.1 Logic level Mode
The serial UART interface can be used in a host controller application with a UART interface. The
design of the interface depends on the power supply voltage of the host system; see Figure 12
for a 3.0/3.3V host system and Figure 13 for a 5V host system.
Figure 12: A complete UART interface with a
3.0/3.3V host system.
Figure 13: A complete UART interface with a 5V host
system.
