C/T2:
Timer or counter select. 0 is for timer and 1 is for external event counter.
CP/RL2:
Capture/Reload flag. When set, captures will occurs on a negative transition at
T2EX
if
EXEN2=1.
When cleared, auto-reloads will occur either with Timer2 overflows or a negative transition at
T2EX
when
EXEN2=1.
When whether
TCLK
or
RCLK
is 1, this bits is ignored and the timer is
forced to auto-reload on Timer2 overflow.
TIMER0 (T0) AND TIMER1 (T1)
Mode 0
The timer register is configured as a 13-bits register. As when the count rolls over from all 1s to
all 0s, it sets the timer interrupt flag
TFx.
The counted input is enabled to the timer when
TRx
= 1
and either GATE=0 or INTx = 1. Mode 0 operation is the same for Timer0 and Timer1.
OSC/12
T0 or T1 pin
(sampled)
C//T
0
1
0
1
TLx[4:0] THx[7:0]
TFx
Interrupt
TRx
GATE
/INTx
Mode 0
Mode 1
Mode1 is the same as Mode0, except that the timer register is being run with all 16 bits.
OSC/12
T0 or T1 pin
(sampled)
C//T
TRx
GATE
/INTx
0
1
0
1
TLx[7:0] THx[7:0]
TFx
Interrupt
Mode 1
Mode 2
Mode 2 configures the timer register as an 8-bits counter (TLx) with automatic reload. Overflow
from TLx does not only set TFx, but also reloads TLx with the content of THx, which is
determined by user’s program. The reload leaves THx unchanged. Mode 2 operation is the
same for Timer0 and Timer1.
MEGAWIN
MPC89x51A Data Sheet
15