Auxiliary Control Register (Duacr); Interrupt Status Register (Duisr); Interrupt Mask Register (Duimr); Interrupt Vector Register (Duivr) - Motorola MC68306 User Manual

shown in Figure 6-9. The mode, status, command, and clock-select registers are
duplicated for each channel to provide independent operation and control.
All serial module registers are only accessible as bytes. The
contents of the mode registers (DUMR1 and DUMR2), clock-
select register (DUCSR), and the auxiliary control register
(DUACR) bit 7 should only be changed after the
receiver/transmitter is issued a software RESET command—
i.e., channel operation must be disabled. Care should also be
taken if the register contents are changed during
receiver/transmitter operations, as undesirable results may be
produced.
In the registers discussed in the following pages, the numbers above the register
description represent the bit position in the register. The register description contains the
mnemonic for the bit. The values shown below the register description are the values of
those register bits after a hardware reset. A value of U indicates that the bit value is
unaffected by reset. The read/write status is shown in the last line.
Address
FFFFF7E1 MODE REGISTER A (DUMR1A, DUMR2A)
FFFFF7E3 STATUS REGISTER A (DUSRA)
FFFFF7E5
FFFFF7E7 RECEIVER BUFFER A (DURBA)
FFFFF7E9 INPUT PORT CHANGE REGISTER (DUIPCR)
FFFFF7EB

INTERRUPT STATUS REGISTER (DUISR)

FFFFF7ED COUNTER MODE:CURRENT MSB OF COUNTER
FFFFF7EF COUNTER MODE:CURRENT LSB OF COUNTER
FFFFF7F1 MODE REGISTER B (DUMR1B, DUMR2B)
FFFFF7F3 STATUS REGISTER B (DUSRB)
FFFFF7F5
FFFFF7F7 RECEIVER BUFFER B (DURBB)
FFFFF7F9

INTERRUPT VECTOR REGISTER (DUIVR)

FFFFF7FB INPUT PORT REGISTER (DUIP)
START COUNTER COMMAND 2
FFFFF7FD
STOP COUNTER COMMAND 2
FFFFF7FF
NOTES:
1. This address is used for factory testing and should not be read. Reading this location wiill result in undesired effects and
possible incorrect transmission or reception of characters. Register contents may also be changed.
2. Address-triggered commands
6.4.1.1 MODE REGISTER 1 (DUMR1). DUMR1 controls some of the serial module
configuration. This register can be read or written at any time. It is accessed when the
6-18
Register Read (R/W = 1)
DO NOT ACCESS 1
DO NOT ACCESS 1

Figure 6-9. Serial Module Programming Model

MC68306 USER'S MANUAL
NOTE
Register Write (R/W = 0)
MODE REGISTER A (DUMR1A, DUMR2A)
CLOCK-SELECT REGISTER A (DUCSRA)
COMMAND REGISTER A (DUCRA)
TRANSMITTER BUFFER A (DUTBA)

AUXILIARY CONTROL REGISTER (DUACR)

INTERRUPT MASK REGISTER (DUIMR)

COUNTER/TIMER UPPER REGISTER
COUNTER/TIMER LOWER REGISTER
MODE REGISTER B (DUMR1B, DUMR2B)
CLOCK-SELECT REGISTER B (DUCSRB)
COMMAND REGISTER B (DUCRB)
TRANSMITTER BUFFER B (DUTBB)
INTERRUPT VECTOR REGISTER (DUIVR)
OUTPUT PORT CONFIGURATION REGISTER
OUTPUT PORT (DUOP) 2 BIT SET
OUTPUT PORT (DUOP) 2 BIT RESET
(DUOPCR)
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