MOTOROLA
MC68341 USER’S MANUAL
7- 25
Table 7-5. RCx Control Bits
RC1
RC0
Command
0
No Action Taken
0
1
Enable Receiver
1
0
Disable Receiver
1
Do Not Use
No Action Taken—The no action taken command causes the receiver to stay in its
current mode. If the receiver is enabled, it remains enabled; if disabled, it remains
disabled.
Receiver Enable—The receiver enable command enables operation of the channel's
receiver. If the serial module is not in multidrop mode, this command also forces the
receiver into the search-for-start-bit state. If the receiver is already enabled, this
command has no effect.
Receiver Disable—The receiver disable command disables the receiver immediately.
Any character being received is lost. The command has no effect on the receiver status
bits or any other control register. If the serial module is programmed to operate in the
local loopback mode or multidrop mode, the receiver operates even though this
command is selected. If the receiver is already disabled, this command has no effect.
Do Not Use—Do not use this bit combination because the result is indeterminate.
7.4.1.4 INPUT PORT CHANGE REGISTER (IPCR). The IPCR shows the current state
and the change-of-state for the CTSA and CTSB pins. This register can only be read when
the serial module is enabled (i.e., the STP bit in the MCR is cleared).
IPCR
$714
76543210
0
COSB
COSA
0
CTSB
CTSA
RESET:
000000U
U
Read Only
Supervisor/User
Bits 7, 6, 3, 2—Reserved by Motorola
COSB, COSA—Change-of-State
1 = A change-of-state (high-to-low or low-to-high transition), lasting longer than 25–
50
s when using a crystal as the sampling clock or longer than one or two
periods when using SCLK, has occurred at the corresponding CTS≈ input (MCR
ICCS bit controls selection of the sampling clock for clear-to-send operation).
When these bits are set, the ACR can be programmed to generate an interrupt to
the CPU32.
0 = The CPU32 has read the IPCR. No change-of-state has occurred. A read of the
IPCR also clears the ISR COS bit.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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