ST16C580
SYMBOL DESCRIPTION
Symbol
Pin
44
Signal
type
Pin Description
40
48
UART’stransmitorreceiveoperation.
-RI
39
43
36
41
I
RingIndicator(activelow)-Alogic0onthispinindicatesthe
modem has received a ringing signal from the telephone
line. A logic 1 transition on this input pin will generate an
interrupt.
-RTS
32
32
O
Request to Send (active low) - A logic 0 on the -RTS pin
indicatesthetransmitterhasdatareadyandwaitingtosend.
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
10
11
7
I
Receive Data - This pin provides the serial receive data
input to the 580. Two user selectable interface options are
available. 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
11
13
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.
Rev.1.20
7
EXAR [ EXAR CORPORATION ]
