C8051F020/1/2/3
23.2.
Capture/Compare Modules
Each module can be configured to operate independently in one of six operation modes: Edge-triggered Capture,
Software Timer, High Speed Output, Frequency Output, 8-Bit Pulse Width Modulator, or 16-Bit Pulse Width Modu-
lator. Each module has Special Function Registers (SFRs) associated with it in the CIP-51 system controller. These
registers are used to exchange data with a module and configure the module's mode of operation.
ule’s operating modes. Setting the ECCFn bit in a PCA0CPMn register enables the module's CCFn interrupt. Note:
PCA0 interrupts must be globally enabled before individual CCFn interrupts are recognized. PCA0 interrupts are glo-
bally enabled by setting the EA bit (IE.7) and the EPCA0 bit (EIE1.3) to logic 1. See Figure 23.3 for details on the
PCA interrupt configuration.
Table 23.2. PCA0CPM Register Settings for PCA Capture/Compare Modules
PWM16 ECOM
X
X
X
X
X
X
0
1
X
X
X
CAPP CAPN
1
0
1
0
1
1
0
0
0
0
0
MAT
0
0
0
1
1
X
X
X
TOG
0
0
0
0
1
1
0
0
PWM ECCF Operation Mode
Capture triggered by positive edge on
0
X
CEXn
Capture triggered by negative edge on
0
X
CEXn
Capture triggered by transition on
0
X
CEXn
0
X
Software Timer
0
X
High Speed Output
1
X
Frequency Output
1
X
8-Bit Pulse Width Modulator
1
X
16-Bit Pulse Width Modulator
1
0
1
0
1
0
1
0
1
0
X = Don’t Care
Figure 23.3. PCA Interrupt Block Diagram
(for n = 0 to 4)
PCA0CPMn
P
EC
W
CA
M
OP
1
MP
6
n n
n
C
A
P
N
n
MT
P
E
AO
W
C
TG
M
C
n n
n
F
n
PCA0CN
CC
F R
C
C
F
4
C
C
F
3
C
C
F
2
C
C
F
1
C
C
F
0
C
I
D
L
PCA0MD
C
P
S
2
C
P
S
1
CE
PC
S F
0
PCA Counter/
Timer Overflow
0
1
ECCF0
PCA Module 0
(CCF0)
ECCF1
0
1
EPCA0
(EIE1.3)
0
1
EA
(IE.7)
0
1
Interrupt
Priority
Decoder
PCA Module 1
(CCF1)
ECCF2
0
1
PCA Module 2
(CCF2)
ECCF3
0
1
PCA Module 3
(CCF3)
ECCF4
0
1
PCA Module 4
(CCF4)
0
1
252
Rev. 1.4
SILABS [ SILICON LABORATORIES ]
