Raven Interrupt Controller Implementation
http://www.motorola.com/computer/literature
2-67
2
CI COUNT INHIBIT. Setting this bit to one inhibits counting for this
timer. Setting this bit to zero allows counting to proceed.
BC BASE COUNT. This field contains the 31 bit count for this timer.
When a value is written into this register and the CI bit transitions from a
1 to a 0, it is copied into the corresponding Current Count register and the
toggle bit in the Current Count register is cleared. When the timer counts
down to zero, the Current Count register is reloaded from the Base Count
register and the interrupt becomes pending in MPIC processing.
Timer Vector/Priority Registers
MASK MASK. Setting this bit disables any further interrupts from this
source. If the mask bit is cleared while the bit associated with this interrupt
is set in the IPR, the interrupt request will be generated.
ACT ACTIVITY. The activity bit indicates that an interrupt has been
requested or that it is in-service. The ACT bit is set to a one when its
associated bit in the Interrupt Pending Register or In-Service Register is
set.
PRIOR Interrupt priority 0 is the lowest and 15 is the highest. Note that
a priority level of 0 will not enable interrupts.
Offset
Timer 0 - $01120
Timer 1 - $01160
Timer 2 - $011A0
Timer 3 - $011E0
Bit
3
1
3
0
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
1
9
1
8
1
7
1
6
1
5
1
4
1
3
1
2
1
1
1
0 9 8 7 6 5 4 3 2 1 0
Name
TIMER VECTOR/PRIORITY
MA
S
K
AC
T
PRIOR
VECTOR
Operation
R/W
R
R
R/W
R
R/W
Reset
1
0
$000
$0
$00
$00