Philips Semiconductors
Preliminary data
P89C51RB2/P89C51RC2/
P89C51RD2
80C51 8-bit Flash microcontroller family
16KB/32KB/64KB ISP/IAP Flash with 512B/512B/1KB RAM
2001 Jun 27
24
CMOD Address = D9H
Reset Value = 00XX X000B
CIDL
WDTE
–
CPS1
CPS0
ECF
Bit:
Symbol
Function
CIDL
Counter Idle control: CIDL = 0 programs the PCA Counter to continue functioning during idle Mode. CIDL = 1 programs
it to be gated off during idle.
WDTE
Watchdog Timer Enable: WDTE = 0 disables Watchdog Timer function on PCA Module 4. WDTE = 1 enables it.
–
Not implemented, reserved for future use.*
CPS1
PCA Count Pulse Select bit 1.
CPS0
PCA Count Pulse Select bit 0.
CPS1
CPS0
Selected PCA Input**
0
Internal clock, fOSC/6 in 6 clock mode (fOSC/12 in 12 clock mode)
0
1
Internal clock, fOSC/2 in 6 clock mode (fOSC/4 in 12 clock mode)
1
0
2
Timer 0 overflow
1
3
External clock at ECI/P1.2 pin
(max. rate = fOSC/4 in 6 clock mode, fOCS/8 in 12 clock mode)
ECF
PCA Enable Counter Overflow interrupt: ECF = 1 enables CF bit in CCON to generate an interrupt. ECF = 0 disables
that function of CF.
NOTE:
*
User software should not write 1s to reserved bits. These bits may be used in future 8051 family products to invoke new features. In that case, the reset or inactive value of the
new bit will be 0, and its active value will be 1. The value read from a reserved bit is indeterminate.
** fOSC = oscillator frequency
SU01318
7
6
5
432
1
0
Figure 17. CMOD: PCA Counter Mode Register
CCON Address = D8H
Reset Value = 00X0 0000B
CF
CR
–
CCF4
CCF3
CCF2
CCF1
CCF0
Bit Addressable
Bit:
Symbol
Function
CF
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.
CR
PCA Counter Run control bit. Set by software to turn the PCA counter on. Must be cleared by software to turn the PCA
counter off.
–
Not implemented, reserved for future use*.
CCF4
PCA Module 4 interrupt flag. Set by hardware when a match or capture occurs. Must be cleared by software.
CCF3
PCA Module 3 interrupt flag. Set by hardware when a match or capture occurs. Must be cleared by software.
CCF2
PCA Module 2 interrupt flag. Set by hardware when a match or capture occurs. Must be cleared by software.
CCF1
PCA Module 1 interrupt flag. Set by hardware when a match or capture occurs. Must be cleared by software.
CCF0
PCA Module 0 interrupt flag. Set by hardware when a match or capture occurs. Must be cleared by software.
NOTE:
*
User software should not write 1s to reserved bits. These bits may be used in future 8051 family products to invoke new features. In that case, the reset or inactive value of
the new bit will be 0, and its active value will be 1. The value read from a reserved bit is indeterminate.
SU01319
76
5
4
3
210
Figure 18. CCON: PCA Counter Control Register