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Universal Asynchronous Receiver/Transmitter
11-8
MC68328 USER’S MANUAL 12/9/97
MOTOROLA
UART
11
PRELIMINARY
TX EN—Transmitter Enable
This bit enables the transmitter block. When this bit is low, the transmitter is disabled and
the transmit FIFO is flushed. This bit resets to 0.
0 = Transmitter disabled and transmit FIFO flushed.
1 = Transmitter enabled.
CLK MODE—Receiver Clock Mode
This bit controls the operating mode of the receiver. When this bit is low, the receiver is in
16x mode where it synchronizes to the incoming data stream and samples at the perceived
center of each bit period. When this bit is high, the receiver is in 1x mode where it samples
the datastream on each rising edge of the bit clock. This bit resets to 0.
0 = 16x clock mode.
1 = 1x clock mode.
PAR EN—Parity Enable
This bit controls the parity generator in the transmitter and parity checker in the receiver.
When this bit is high, they are enabled and when it is low, they are disabled.
0 = Parity disabled.
1 = Parity enabled.
ODD EVEN—Odd or Even Parity Selection
This bit controls the sense of the parity generator and checker. When this bit is high, odd
parity is generated on the transmitter and expected on the receiver. When it is low, even
parity is generated and expected. This bit has no function if PARITY EN is low.
0 = Even parity.
1 = Odd parity.
STOP—STOP Bit Selection
This bit controls the number of stop bits transmitted after a character. When this bit is high,
two stop bits are sent and when it is low, one stop bit is sent. This bit has no effect on the
receiver, which expects one or more stop bits.
0 = One STOP bit transmitted.
1 = Two STOP bits transmitted.
8/7—Character Word Length
This bit controls the character length. When this bit is high, the transmitter and receiver are
in 8-bit mode. When it is low, they are in 7-bit mode. The transmitter then ignores B7 and
the receiver sets B7 to 0.
0 = 7 transmit and receive bits per character.
1 = 8 transmit and receive bits per character.