AT89C51RB2/RC2
Table 25. PCA Module Modes (CCAPMn Registers)
ECOMn CAPPn CAPNn
MATn
TOGn
PWMm ECCFn Module Function
0
0
1
0
0
0
0
0
0
0
No Operation
16-bit capture by a positive-edge
trigger on CEXn
X
0
0
0
1
0
0
0
0
X
16-bit capture by a negative trigger
on CEXn
X
X
1
0
1
0
1
1
0
0
0
0
X
X
X
16-bit capture by a transition on
CEXn
16-bit Software Timer/Compare
mode.
1
1
1
0
0
0
0
0
0
1
0
1
1
0
0
1
0
X
0
16-bit High-speed Output
8-bit PWM
X
X
Watchdog Timer (Module 4 only)
There are two additional registers associated with each of the PCA Modules. They are
CCAPnH and CCAPnL and these are the registers that store the 16-bit count when a
capture occurs or a compare should occur. When a Module is used in the PWM mode
these registers are used to control the duty cycle of the output (see Table 26 and
Table 27).
Table 26. CCAPnH Registers (n = 0-4)
CCAP0H – PCA Module 0 Compare/Capture Control Register High (0FAh)
CCAP1H – PCA Module 1 Compare/Capture Control Register High (0FBh)
CCAP2H – PCA Module 2 Compare/Capture Control Register High (0FCh)
CCAP3H – PCA Module 3 Compare/Capture Control Register High (0FDh)
CCAP4H – PCA Module 4 Compare/Capture Control Register High (0FEh)
7
-
6
-
5
-
4
-
3
-
2
-
1
-
0
-
Bit
Bit
Number
Mnemonic Description
PCA Module n Compare/Capture Control
CCAPnH Value
7 - 0
-
Reset Value = 0000 0000b
Not bit addressable
37
4180E–8051–10/06
ATMEL [ ATMEL ]
