
MC68331
USER’S MANUAL
REGISTER SUMMARY
MOTOROLA
D-7
D
D.2.7 PACTL
— Pulse Accumulator Control Register
PACNT
— Pulse Accumulator Counter
$YFF90C
$YFF90D
PACTL enables the pulse accumulator and selects either event counting or gated
mode. In event counting mode, PACNT is incremented each time an event occurs. In
gated mode, it is incremented by an internal clock.
PAIS — PAI Pin State (Read Only)
PAEN — Pulse Accumulator Enable
0 = Pulse accumulator disabled
1 = Pulse accumulator enabled
PAMOD — Pulse Accumulator Mode
0 = External event counting
1 = Gated time accumulation
PEDGE — Pulse Accumulator Edge Control
The effects of PEDGE and PAMOD are shown in the following table.
PCLKS — PCLK Pin State (Read Only)
I4/O5 — Input Capture 4/Output Compare 5
0 = Output compare 5 enabled
1 = Input capture 4 enabled
PACLK[1:0] — Pulse Accumulator Clock Select (Gated Mode)
PACNT — Pulse Accumulator Counter
Eight-bit read/write counter used for external event counting or gated time accumula-
tion.
15
14
13
12
11
10
9
8
7
0
PAIS
PAEN
PAMOD
PEDGE
PCLKS
I4/O5
PACLK
PACNT
RESET:
U
0
0
0
U
0
0
0
0
0
0
0
0
0
0
0
PAMOD
0
0
1
1
PEDGE
0
1
0
1
Effect
PAI Falling Edge Increments Counter
PAI Rising Edge Increments Counter
Zero on PAI Inhibits Counting
One on PAI Inhibits Counting
PACLK[1:0]
00
01
10
11
Pulse Accumulator Clock Selected
System Clock Divided by 512
Same Clock Used to Increment TCNT
TOF Flag from TCNT
External Clock, PCLK