Serial Communications (16C452)
Request-To-Send (RTS0*, RTS1*)
The RTS* pin is set active (low) by writing a logical 1 to bit 1 of the
associated UART’s Modem Control register. Both RTS* pins are
disabled (set high) by reset. The RTS* signal on each UART is used
to enable the modem. When active, an RTS* pin indicates that its
UART has data ready to transmit. In half-duplex operations, RTS* is
used to control the direction of the line.
Serial Data Inputs (SIN0, SIN1)
The serial data inputs move information from the communication line
or modem to the UART receiver circuits. A mark (1) is high; a space
(0) is low. Data on serial data inputs is disabled when operating in the
loopback mode.
Serial Data Outputs (SOUT0, SOUT1)
These lines are the serial data outputs from the UARTs’ transmitter
circuitry. A mark (1) is a logical 1 (high); a space (0) is a logical 0
(low). Each SOUT is held in the mark condition when the transmitter
is disabled, when RESET* is active (low), when the Transmitter
register is empty, or when in the loopback mode.
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