ST16C550 Exar Corporation, ST16C550 Datasheet - Page 7

• Manufacturer Part Number: ST16C550
• Description: UART WITH 16-BYTE FIFO
• Manufacturer: Exar Corporation

SYMBOL DESCRIPTION
-CTS
-DSR
-DTR
-RI
-RTS
RX
TX
Symbol
Rev. 4.30
37
33
32
40
36
39
10
11
Pin
44
41
37
43
36
11
13
40
48
38
39
33
32
41
7
8
Signal
type
O
O
O
I
I
I
I
Data Terminal Ready (active low) - A logic 0 on this pin
Request to Send (active low) - A logic 0 on the -RTS pin
Clear to Send (active low) - A logic 0 on the -CTS pin indicates
the modem or data set is ready to accept transmit data from
the ST16C550. Status can be tested by reading MSR bit-4.
This pin has no effect on the UART’s transmit or receive
operation.
Data Set Ready (active low) - A logic 0 on this pin indicates
the modem or data set is powered-on and is ready for data
exchange with the UART. This pin has no effect on the
UART’s transmit or receive operation.
indicates that the ST16C550 is powered-on and ready. This
pin can be controlled via the modem control register.
Writing a logic 1 to MCR bit-0 will set the -DTR output to
logic 0, enabling the modem. This pin will be a logic 1 after
writing a logic 0 to MCR bit-0, or after a reset. This pin has
no effect on the UART’s transmit or receive operation.
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.
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 has no effect
on the UART’s transmit or receive operation.
Receive Data - This pin provides the serial receive data
input to the ST16C550. A logic 1 indicates no data or an idle
channel. 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.
Transmit Data - This pin provides the serial transmit data
from the ST16C550, the TX signal will be a logic 1 during
reset, idle (no data). During the local loop-back mode, the
TX pin is set to a logic 1 and TX data is internally connected
to the UART RX Input, see figure 12.
7
Pin Description
ST16C550