Motorola MC68340 manual Acr, Isr

Freescale Semiconductor, Inc...

Freescale Semiconductor, Inc.

7.4.1.11AUXILIARY 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							$714
	7	6	5	4	3	2	1	0
	BRG	0	0	0	0	0	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.

7.4.1.12INTERRUPT 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							$715
7	6	5	4	3	2	1	0
COS	DBB	RxRDYB TxRDYB		XTAL_	DBA	RxRDYA TxRDYA
				RDY
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- 32MC68340 USER’S MANUALMOTOROLA

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