Freescale Semiconductor, Inc.
7.4.1.11 AUXILIARY CONTROL REGISTER (ACR). The ACR selects which baud rate is
used and controls the handshake of the transmitter/receiver. This register can only be
written when the serial module is enabled (i.e., the STP bit in the MCR is cleared).
ACR
7
$714
0
6
0
5
0
4
0
3
0
2
0
1
BRG
IECB
IECA
RESET:
0
0
0
0
0
0
0
0
Write Only
Supervisor/User
BRG—Baud Rate Generator Set Select
1 = Set 2 of the available baud rates is selected.
0 = Set 1 of the available baud rates is selected. Refer to 7.4.1.6 Clock-Select
Register (CSR) for more information on the baud rates.
IECB, IECA—Input Enable Control
1 = ISR bit 7 will be set and an interrupt will be generated when the corresponding bit
in the IPCR (COSB or COSA) is set by an external transition on the channel's
CTS≈ input (if bit 7 of the interrupt enable register (IER) is set to enable
interrupts).
0 = Setting the corresponding bit in the IPCR has no effect on ISR bit 7.
7.4.1.12 INTERRUPT STATUS REGISTER (ISR). The ISR provides status for all potential
interrupt sources. The contents of this register are masked by the IER. If a flag in the ISR
is set and the corresponding bit in IER is also set, the IRQ≈ output is asserted. If the
corresponding bit in the IER is cleared, the state of the bit in the ISR has no effect on the
output. This register can only be read when the serial module is enabled (i.e., the STP bit
in the MCR is cleared).
NOTE
The IER does not mask reading of the ISR. True status is
provided regardless of the contents of IER. The contents of
ISR are cleared when the serial module is reset.
ISR
7
$715
6
5
4
3
2
1
0
COS
DBB RxRDYB TxRDYB XTAL_
RDY
DBA RxRDYA TxRDYA
RESET:
0
0
0
0
1
0
0
0
Read Only
Supervisor/User
COS—Change-of-State
1 = A change-of-state has occurred at one of the CTS≈ inputs and has been
selected to cause an interrupt by programming bit 1 and/or bit 0 of the ACR.
0 = The CPU32 has read the IPCR.
7- 32
MC68340 USER’S MANUAL
MOTOROLA
For More Information On This Product,
Go to: www.freescale.com
FREESCALE [ Freescale ]
