Atmel AT89C52

OSC
EXF2
TF2
T2EX PIN
COUNT
DIRECTION
1=UP
0=DOWN
T2 PIN
TR2
CONTROL
OVERFLOW
(DOWN COUNTING RELOAD VALUE)
(UP COUNTING RELOAD VALUE)
TOGGLE
TIMER 2
INTERRUPT
12
RCAP2LRCAP2H
0FFH0FFH
TH2 TL2
C/T2 = 0
C/T2 = 1
÷
Figure 3. Timer 2 Auto Reload Mode (DCEN = 1)
OSC
SMOD1
RCLK
TCLK
Rx
CLOCK
Tx
CLOCK
T2EX PIN
T2 PIN
TR2
CONTROL
"1"
"1"
"1"
"0"
"0"
"0"
TIMER 1 OVERFLOW
NOTE: OSC. FREQ. IS DIVIDED BY 2, NOT 12
TIMER 2
INTERRUPT
2
2
6
16
RCAP2LRCAP2H
TH2 TL2
C/T2 = 0
C/T2 = 1
EXF2
CONTROL
TRANSITION
DETECTOR
EXEN2
÷
÷
÷
÷
Figure 4. Timer 2 in Baud Rate Generator Mode
8 AT89C52