ST16C580
6
Rev. 1.22
-RI
41
I
Ring Indicator (active low) - A logic 0 on this pin indicates the
modem has received a ringing signal from the telephone
line. A logic 1 transition on this input pin will generate an
interrupt.
-RTS
32
O
Request to Send (active low) - A logic 0 on the -RTS pin
indicates the transmitter has data ready and waiting to send.
Writing a logic 1 in the modem control register (MCR bit-1)
will set this pin to a logic 0 indicating data is available. After
a reset this pin will be set to a logic 1. This pin only affects
the transmit and receive operations when Auto RTS func-
tion is enabled via the Enhanced Feature Register (EFR)
bit-6, for hardware flow control operation.
RX / IRRX
7
I
Receive Data - This pin provides the serial receive data input
to the 580. Two user selectable interface options are avail-
able. The first option supports the standard modem interface.
The second option provides an Infrared decoder interface, see
figures 2/3. When using the standard modem interface, the
RX signal will be a logic 1 during reset, idle (no data), or when
the transmitter is disabled. The inactive state (no data) for the
Infrared decoder interface is a logic 0. MCR bit-6 selects the
standard modem or infrared interface. During the local loop-
back mode, the RX input pin is disabled and TX data is
internally connected to the UART RX Input, internally, see
figure 12.
TX/IRTX
8
O
Transmit Data - This pin provides the serial transmit data from
the 580. Two user selectable interface options are available.
The first user option supports a standard modem interface.
The second option provides an Infrared encoder interface, see
figures 2/3. When using the standard modem interface, the TX
signal will be a logic 1 during reset, idle (no data), or when the
transmitter is disabled. The inactive state (no data) for the
Infrared encoder/ decoder interface is a Logic 0. MCR bit-6
selects the standard modem or infrared interface. During the
local loop-back mode, the TX input pin is disabled and TX data
is internally connected to the UART RX Input, see figure 12.
SYMBOL DESCRIPTION
Symbol
Pin
Signal
Pin Description
48
type