Rainbow Electronics AT89C55WD - Manual (Page 14)

14
AT89C55WD
1921B–MICRO–09/02
Figure 7. Timer 2 Auto Reload Mode (DCEN = 1)
Figure 8. Timer 2 in Baud Rate Generator Mode
OSC
EXF2
TF2
T2EX PIN
COUNT
DIRECTION
1=UP
0=DO
T2 PIN
TR2
CONTROL
OVERFLOW
TOGGLE
TIMER 2
INTERRUPT
12
RCAP2L RCAP2H
0FFH 0FFH
TH2 TL2
C/T2 = 0
C/T2 = 1
÷
(DOWN COUNTING RELOAD VALUE)
(UP COUNTING RELOAD VALUE)
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
16
16
RCAP2L RCAP2H
TH2 TL2
C/T2 = 0
C/T2 = 1
EXF2
CONTROL
TRANSITION
DETECTOR
EXEN2
ч
ч
ч
ч