
34
AT89C51RB2/RC2
4180E–8051–10/06
Table 23. CCON Register
CCON – PCA Counter Control Register (D8h)
Reset Value = 000X 0000b
Bit addressable
The watchdog timer function is implemented in Module 4 (see
Figure 14).The PCA interrupt system is shown in
Figure 12.
76
54
32
1
0
CF
CR
-
CCF4
CCF3
CCF2
CCF1
CCF0
Bit
Number
Bit
Mnemonic
Description
7CF
PCA Counter Overflow Flag
Set by hardware when the counter rolls over. CF flags an interrupt if bit ECF in
CMOD is set. CF may be set by either hardware or software but can only be
cleared by software.
6CR
PCA Counter Run Control Bit
Must be cleared by software to turn the PCA counter off.
Set by software to turn the PCA counter on.
5-
Reserved
The value read from this bit is indeterminate. Do not set this bit.
4
CCF4
PCA Module 4 Interrupt Flag
Must be cleared by software.
Set by hardware when a match or capture occurs.
3
CCF3
PCA Module 3 Interrupt Flag
Must be cleared by software.
Set by hardware when a match or capture occurs.
2
CCF2
PCA Module 2 Interrupt Flag
Must be cleared by software.
Set by hardware when a match or capture occurs.
1
CCF1
PCA Module 1 Interrupt Flag
Must be cleared by software.
Set by hardware when a match or capture occurs.
0
CCF0
PCA Module 0 Interrupt Flag
Must be cleared by software.
Set by hardware when a match or capture occurs.