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ST162552

DUAL ASYNCHRONOUS RECEIVER/TRANSMITTER WITH FIFOs

Exar Corporation 

ST16C2552

BIT-2 BIT-1

0

0

0

1

1

0

1

1

MF* Function

OP2*

BAUDOUT*

RXRDY*

Reserved

AFR BIT 3-7:

Not used. All these bits are set to logic zero.

LINE CONTROL REGISTER (LCR)

The Line Control Register is used to specify the

asynchronous data communication format. The num-

ber of the word length, stop bits, and parity can be

selected by writing appropriate bits in this register.

LCR BIT1-0:

These two bits specify the word length to be transmit-

ted or received.

BIT-1 BIT-0

0

0

0

1

1

0

1

1

Word length

5

6

7

8

LCR BIT-2:

The number of stop bits can be specified by this bit.

BIT-2 Word length Stop bit(s)

0

5,6,7,8

1

5

1

6,7,8

1

1-1/2

2

LCR BIT-3:

Parity or no parity can be selected via this bit.

0=no parity

1=a parity bit is generated during the transmission,

receiver also checks for received parity.

LCR BIT-4:

If the parity bit is enabled, LCR BIT-4 selects the even

or odd parity format.

0=ODD parity is generated by forcing an odd number

of 1’s in the transmitted data, receiver also checks for

same format.

1= EVEN parity bit is generated by forcing an even

number of 1’s in the transmitted data, receiver also

checks for same format.

LCR BIT-5:

If the parity bit is enabled, LCR BIT-5 selects the

forced parity format.

LCR BIT-5=1 and LCR BIT-4=0, parity bit is forced to

“1” in the transmitted and received data.

LCR BIT-5=1 and LCR BIT-4=1, parity bit is forced to

“0” in the transmitted and received data.

LCR BIT-6:

Break control bit. It causes a break condition to be

transmitted (the TX is forced to low state).

0=normal operating condition.

1=forces the transmitter output (TX) to go low to alert

the communication terminal.

LCR BIT-7:

The internal baud rate counter latch enable (DLAB).

0=normal operation.

1=select Divisor Latch Register and Alternate Func-

tion Register.

MODEM CONTROL REGISTER (MCR)

This register controls the interface with the MODEM

or a peripheral device (RS232).

MCR BIT-0:

0=force DTR* output to high.

1=force DTR* output to low.

MCR BIT-1:

0=force RTS* output to high.

1=force RTS* output to low.

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