
Timing System
Pulse Accumulator
MC68HC11E Family
—
Rev. 4
Technical Data
MOTOROLA
Timing System
205
9.8.1 Pulse Accumulator Control Register
Four of this register
’
s bits control an 8-bit pulse accumulator system.
Another bit enables either the OC5 function or the IC4 function, while two
other bits select the rate for the real-time interrupt system.
DDRA7
—
Data Direction for Port A Bit 7
Refer to
Section 6. Parallel Input/Output (I/O) Ports
.
PAEN
—
Pulse Accumulator System Enable Bit
0 = Pulse accumulator disabled
1 = Pulse accumulator enabled
PAMOD
—
Pulse Accumulator Mode Bit
0 = Event counter
1 = Gated time accumulation
PEDGE
—
Pulse Accumulator Edge Control Bit
This bit has different meanings depending on the state of the PAMOD
bit, as shown in
Table 9-7
.
Address:
$1026
Bit 7
6
5
4
3
2
1
Bit 0
Read:
DDRA7
PAEN
PAMOD
PEDGE
DDRA3
I4/O5
RTR1
RTR0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 9-25. Pulse Accumulator Control Register (PACTL)
Table 9-7. Pulse Accumulator Edge Control
PAMOD
PEDGE
Action on Clock
0
0
PAI falling edge increments the counter.
0
1
PAI rising edge increments the counter.
1
0
A 0 on PAI inhibits counting.
1
1
A 1 on PAI inhibits counting.