Rainbow Electronics T89C51AC2 - Manual (Page 70)

70
T89C51AC2
Rev. B – 19-Dec-01
Figure 30. PCA Timer/Counter
The CMOD register includes three additional bits associated with the PCA.
• The CIDL bit which allows the PCA to stop during idle mode.
• The WDTE bit which enables or disables the watchdog function on module 4.
• The ECF bit which when set causes an interrupt and the PCA overflow flag CF in
CCON register to be set when the PCA timer overflows.
The CCON register contains the run control bit for the PCA and the flags for the PCA
timer and each module.
• The CR bit must be set to run the PCA. The PCA is shut off by clearing this bit.
• The CF bit is set when the PCA counter overflows and an interrupt will be generated
if the ECF bit in CMOD register is set. The CF bit can only be cleared by software.
• The CCF0:4 bits are the flags for the modules (CCF0 for module0...) and are set by
hardware when either a match or a capture occurs. These flags also can be cleared
by software.
15.2 PCA modules Each one of the five compare/capture modules has six possible functions. It can
perform:
• 16-bit Capture, positive-edge triggered
• 16-bit Capture, negative-edge triggered
• 16-bit Capture, both positive and negative-edge triggered
• 16-bit Software Timer
• 16-bit High Speed Output
• 8-bit Pulse Width Modulator.
In addition module 4 can be used as a Watchdog Timer.
CIDL CPS1 CPS0 ECF
It
CH CL
16 bit up/down counter
To PCA
modules
FPca/6
FPca / 2
T0 OVF
P1.2
Idle
CMOD
0xD9
WDTE
CF CR
CCON
0xD8
CCF4 CCF3 CCF2 CCF1 CCF0
overflow