mc9s12e256 Freescale Semiconductor, Inc, mc9s12e256 Datasheet - Page 431

• Manufacturer Part Number: mc9s12e256
• Description: Hcs12 Microcontrollers 16-bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

13.3.2.17 Pulse Accumulators Count Registers (PACNT)
Read: Anytime
Write: Anytime
These registers contain the number of active input edges on its input pin since the last reset.
When PACNT overflows from 0xFFFF to 0x0000, the Interrupt flag PAOVF in PAFLG (0x0021) is set.
Full count register access should take place in one clock cycle. A separate read/write for high byte and low
byte will give a different result than accessing them as a word.
Freescale Semiconductor
Reset
Reset
W
W
R
R
PACNT15
PACNT7
15
0
0
7
active edge on the pulse accumulator input pin may miss the last count
because the input has to be synchronized with the bus clock first.
Reading the pulse accumulator counter registers immediately after an
Figure 13-24. Pulse Accumulator Count Register High (PACNTH)
Figure 13-25. Pulse Accumulator Count Register Low (PACNTL)
PACNT14
PACNT6
14
0
0
6
PACNT13
PACNT5
MC9S12E256 Data Sheet, Rev. 1.08
13
0
0
5
PACNT12
PACNT4
NOTE
12
0
0
4
PACNT11
PACNT3
11
0
3
0
PACNT10
PACNT2
Chapter 13 Timer Module (TIM16B4CV1)
10
0
0
2
PACNT9
PACNT1
0
0
9
1
PACNT8
PACNT0
0
0
0
0
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