¡ Semiconductor
MSM82C51A-2RS/GS/JS
SYNDET/BD (Input or output terminal)
This is a terminal whose function changes according to mode.
In“internalsynchronousmode.”thisterminalisathighlevel,ifsynccharactersarereceivedand
synchronized. If a status word is read, the terminal will be reset.
In “external synchronous mode, “this is an input terminal.
A “High” on this input forces the MSM82C51A-2 to start receiving data characters.
In “asynchronous mode,” this is an output terminal which generates “high level”output upon
the detection of a “break” character if receiver data contains a “low-level” space between the
stop bits of two continuous characters. The terminal will be reset, if RXD is at high level.
After Reset is active, the terminal will be output at low level.
DSR (Input terminal)
This is an input port for MODEM interface. The input status of the terminal can be recognized
by the CPU reading status words.
DTR (Output terminal)
ThisisanoutputportforMODEMinterface. ItispossibletosetthestatusofDTRbyacommand.
CTS (Input terminal)
This is an input terminal for MODEM interface which is used for controlling a transmit circuit.
The terminal controls data transmission if the device is set in “TX Enable” status by a command.
Data is transmitable if the terminal is at low level.
RTS (Output terminal)
This is an output port for MODEM interface. It is possible to set the status RTS by a command.
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