Timer2 is also can be configured as a periodical signal generator.
The MPC89x52A is able to generate a programmable clock output on P1.0. When T2OE bit is set
and C//T2 bit is cleared, Timer2 overflow pulse will generate a 50% duty clock and output that to
P1.0. The frequency of clock-out is calculated according to the following formula.
Oscillator frequency
4 x (65536 – RCAP2H, RCAP2L)
In the clock-out mode, Timer2 rollovers will not generate an interrupt.
Capture Mode (CP)
In the Capture mode, Timer2 is incremented by either OSC/12 or external pin (T2) 1-to-0
transition. TR2 controls the event to timer2 and a 1-to-0 transition on T2EX pin will trigger
RCAP2H and RCAP2L registers to capture the Timer2 contents onto them if EXEN2 is set. An
overflow in Timer2 sets TF2 flag and a 1-to-0 transition in T2EX pin sets EXF2 flag if EXEN2=1.
TF2 and EXF2 is ORed to request the interrupt service.
0
OSC/12
T2 pin
0
1
TL2 [7:0]
TH2[7:0]
TF2
1
C//T2
TR2
Interrupt
RCAP2L [7:0]
RCAP2H [7:0]
T2EX pin
EXF2
EXEN2
MEGAWIN
MPC89x52A Data Sheet
17
MEGAWIN [ MEGAWIN TECHNOLOGY CO., LTD ]
