ST16C580
LCRBIT-7:
LCR BIT-4:
The internal baud rate counter latch and Enhance
Feature mode enable.
Logic 0 = Divisor latch disabled. (normal default
condition)
Logic 1 = Divisor latch and enhanced feature register
enabled.
If the parity bit is enabled with LCR bit-3 set to a logic
1, LCR BIT-4 selects the even or odd parity format.
Logic 0 = ODD Parity is generated by forcing an odd
number of logic 1’s in the transmitted data. The
receiver must be programmed to check the same
format. (normal default condition)
Modem Control Register (MCR)
Logic 1 = EVEN Parity is generated by forcing an even
the number of logic 1’s in the transmitted. The receiver
must be programmed to check the same format.
This register controls the interface with the modem or
a peripheral device.
LCR BIT-5:
MCR BIT-0:
If the parity bit is enabled, LCR BIT-5 selects the
forced parity format.
LCR BIT-5 = logic 0, parity is not forced (normal
default condition)
Logic 0 = Force -DTR output to a logic 1. (normal
default condition)
Logic 1 = Force -DTR output to a logic 0.
LCR BIT-5 = logic 1 and LCR BIT-4 = logic 0, parity bit
is forced to a logical 1 for the transmit and receive
data.
LCR BIT-5 = logic 1 and LCR BIT-4 = logic 1, parity bit
is forced to a logical 0 for the transmit and receive
data.
MCR BIT-1:
Logic 0 = Force -RTS output to a logic 1. (normal
default condition)
Logic 1 = Force -RTS output to a logic 0.
Automatic RTS may be used for hardware flow control
by enabling EFR bit-6 (See EFR bit-6).
LCR
LCR
LCR
Parity selection
MCR BIT-2:
Bit-5 Bit-4 Bit-3
Logic 0 = Set -OP1 output to a logic 1. (normal default
condition)
X
0
0
1
1
X
0
1
0
1
0
1
1
1
1
No parity
Odd parity
Even parity
Force parity “1”
Forced parity “0”
Logic 1 = Set -OP1 output to a logic 0.
MCR BIT-3:
Logic 0 = Set -OP2 output to a logic 1. (normal default
condition)
Logic 1 = Set -OP2 output to a logic 0.
LCR BIT-6:
MCR BIT-4:
When enabled the Break control bit causes a break
condition to be transmitted (the TX output is forced to
a logic 0 state). This condition exists until disabled by
setting LCR bit-6 to a logic 0.
Logic 0 = Disable loop-back mode. (normal default
condition)
Logic 1 = Enable local loop-back mode (diagnostics).
MCR BIT-5:
Not used.
Logic 0 = No TX break condition. (normal default
condition)
Logic 1 = Forces the transmitter output (TX) to a logic
0 for alerting the remote receiver to a line break
condition.
MCR BIT-6:
Logic 0 = Enable Modem receive and transmit input/
output interface. (normal default condition)
Logic 1 = Enable infrared IrDA receive and transmit
Rev.1.20
22
EXAR [ EXAR CORPORATION ]
