Справочник Пользователя для Silicon Laboratories C8051F342

In Software Timer mode, the PCA counter/timer value is compared to the module's 16-bit capture/compare 
register (PCA0CPHn and PCA0CPLn). When a match occurs, the Capture/Compare Flag (CCFn) in 
PCA0CN is set to logic 1 and an interrupt request is generated if CCF interrupts are enabled. The CCFn bit 
is not automatically cleared by hardware when the CPU vectors to the interrupt service routine, and must 
be cleared by software. Setting the ECOMn and MATn bits in the PCA0CPMn register enables Software 
Timer mode.

Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit 
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.

Match

16-bit Comparator

PCA0H

PCA0CPHn

Enable

PCA0L

PCA
Timebase

PCA0CPLn

0 0

0 0

0

1

x

ENB

ENB

0

1

Write to

PCA0CPLn

Write to

PCA0CPHn

Reset

PCA0CPMn

P

W

M

1
6
n

E
C

O
M

n

E
C
C
F

n

T

O
G

n

P

W

M

n

C
A
P
P

n

C
A
P
N

n

M

A

T
n

x

PCA0CN

C

F

C
R

C
C

F
0

C
C

F
2

C
C

F
1

C
C

F
4

C
C

F
3

PCA Interrupt