MOTOROLA
MC68341 USER’S MANUAL
7- 33
7.4.1.11 MODE REGISTER 1 (MR1). MR1 controls some of the serial module
configuration. This register can be read or written at any time when the serial module is
enabled (i.e., the STP bit in the MCR is cleared).
MR1A, MR1B
$710, $718
76543210
RxRTS
R/F
ERR
PM1
PM0
PT
B/C1
B/C0
RESET:
00000000
Read/Write
Supervisor/User
RxRTS—Receiver Request-to-Send Control
1 = Upon receipt of a valid start bit, RTS≈ is negated if the channel's FIFO is full.
RTS≈ is reasserted when the FIFO has an empty position available.
0 = RTS≈ is asserted by setting bit 1 or 0 in the OP and negated by clearing bit 1 or 0
in the OP.
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 will be disabled for both since
this configuration is incorrect. See 7.4.1.12 Mode Register 2 for information on
programming the transmitter RTS≈ control.
R/F—Receiver-Ready Select
1 = Bit 5 for channel B and bit 1 for channel A in the ISR reflect the channel FIFO full
status. These ISR bits are set when the receiver FIFO is full and are cleared
when a position is available in the FIFO.
0 = Bit 5 for channel B and bit 1 for channel A in the ISR reflect the channel receiver-
ready status. These ISR bits are set when a character has been received and are
cleared when the CPU32 reads the receive buffer.
ERR—Error Mode
This bit controls the meaning of the three FIFO status bits (RB, FE, and PE) in the SR
for the channel.
1 = Block mode—The values in the channel SR 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 command for the channel was issued. Refer to 7.4.1.3
Command Register (CR) for more information on serial module commands.
0 = Character mode—The values in the channel SR reflect the status of the
character at the top of the FIFO.
NOTE
ERR = 0 must be used to get the correct A/D flag information
when in multidrop mode.
F
re
e
sc
a
le
S
e
m
ic
o
n
d
u
c
to
r,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
c
..
.