
μ
PD30102
14
Preliminary Data Sheet
(5) RS-232C interface signals
Signal Name
I/O
Function
RxD
I
This is a receive data signal. It is used when an external device sends serial data to
the V
R
4102.
CTS#
I
This is the transmit enable (“clear-to-send”) signal. This signal is asserted when the
RS-232C controller is ready to receive transmission of serial data.
DCD#/
GPIO15
I
This is a carrier detection signal. Assert this signal active when valid serial data is
being received.
It is also used when detecting a power-on factor for the V
R
4102.
When this is not used as the DCD# signal, this can be used as an interrupt detection
I/O signal for the GIU unit.
DSR#
I
This is the data set ready signal. Assert this signal active to set up transmission and
reception of serial data between the RS-232C controller and the V
R
4102.
TxD/CLKSEL2,
RTS#/CLKSEL1,
DTR#/CLKSEL0
I/O
This function differs depending on the state of the RTCRST# signal.
<When RTCRST# = 1>
These signals are used to perform serial communication.
TxD/CLKSEL2 signal:
This is a transmit data signal. It is used when the V
R
4102 sends serial data to an
external device.
RTS#/CLKSEL1 signal:
This is a transmit request signal. This signal is asserted when the V
R
4102 is ready
to receive serial data from the RS-232C controller.
DTR#/CLKSEL0 signal:
This is a terminal equipment ready signal. This signal is asserted when the V
R
4102
is ready to transmit or receive serial data.
<When RTCRST# = 0>
These signals (CLKSEL (0:2)) are used to set the operating frequency of the CPU core
and the BUSCLK output frequency.
CLKSEL[2:0]
CPU core operating
frequency (MHz)
RFU
RFU
53.6
49.2
45.4
42.1
BUSCLK output
frequency (MHz)
111
110
101
100
011
010
6.700
6.075
5.675
5.275
Caution
The selection of some frequencies shown above may be
disabled in the future.