15-14
MCF5249UM
MOTOROLA
Register Description and Programming
Table 15-3 Mode Register 1 Bit Descriptions
BIT NAME
DESCRIPTION
RxRTS
Receiver Request-to-Send Control
1 = On receipt of a valid start bit, RTS is negated if the UART FIFO is full. RTS is reasserted
when the FIFO has an empty position available.
0 = The receiver has no effect on RTS. The RTS is asserted by writing a one to the Output
Port Bit Set Register (UOP1)
This feature can be used for flow control to prevent overrun in the receiver by using the RTS
output to control the CTS input of the transmitting device. If both the receiver and transmitter
are programmed for RTS control, RTS control is disabled for both because such a
configuration is incorrect.
RxIRQ
On UART 2, RRxIRQ — Receiver Interrupt Select
1 = FFULL is the source that generates IRQ
0 = RxRDY is the source that generates IRQ
ERR
The Error Mode bit controls the meaning of the three FIFO status bits (RB, FE, and PE) in
the USR.
1 = Block mode—The values in the channel USR are the accumulation (i.e., the logical OR)
of the status for all characters coming to the top of the FIFO since the last reset error status
more information on UART module commands.
0 = Character mode—The values in the channel USR reflect the status of the character at
the top of the FIFO.
ERR = 0 must be used to obtain the correct A/D flag information when in multidrop mode.
PM1–PM0
The Parity Mode bits encode the type of parity used for the channel (see
Table 15-4). The
parity bit is added to the transmitted character and the receiver performs a parity check on
incoming data. These bits can alternatively select multidrop mode for the channel.
PT
The Parity Type bit selects the parity type if parity is programmed by the parity mode bits; if
multidrop mode is selected, it configures the transmitter for data character transmission or
address character transmission.
Table 15-4 lists the parity mode and type or the multidrop
mode for each combination of the parity mode and the parity type bits.
Note:
“Force parity low” means forcing a 0 parity bit.
“Force parity high” forces a 1 parity bit.
Table 15-4 PMx and PT Control Bits
PM1
PM0
PARITY MODE
PT
PARITY TYPE
0
With Parity
0
Even Parity
0
With Parity
1
Odd Parity
0
1
Force Parity
0
Low Parity
0
1
Force Parity
1
High Parity
1
0
No Parity
X
No Parity
1
Multidrop Mode
0
Data Character
1
Multidrop Mode
1
Address Character
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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