Interface Circuits
Interfacing SIR transceivers to an RS232
port
A quite common method of adding the IrDA capability
to a desktop computer is the usage of a so-called dongle
connected to the COM - port (RS232 - port). This
connectivity is currently available at any desktop or
laptop computer but in future will be replaced by the
USB port.
For interfacing the SIR frontend transceivers (4000
series) as for other SIR transceivers an Encoder/
Decoder device (TOIM4232) is necessary to provide
the NRZ to RZI conversion. This device also provides
the clock generator and can be programmed by a set
of (8 bit-) commands. Drivers for the RS232 connector
with TOIM4232 are provided by Microsoft (R) with
the Operating Systems. The block diagram of a dongle
connection to RS232 is shown in figure 1