w79e532 Winbond Electronics Corp America, w79e532 Datasheet - Page 42

• Manufacturer Part Number: w79e532
• Description: 8-bit Microcontroller
• Manufacturer: Winbond Electronics Corp America

W79E532/W79L532
Auto-reload Mode, Counting Up
/Down
Timer/Counter 2 will be in auto-reload mode as an up/down counter if CP RL
/
2 bit in T2CON is
cleared and the DCEN bit in T2MOD is set. In this mode, Timer/Counter 2 is an up/down counter
whose direction is controlled by the T2EX pin. A 1 on this pin cause the counter to count up. An
overflow while counting up will cause the counter to be reloaded with the contents of the capture
registers. The next down count following the case where the contents of Timer/Counter equal the
capture registers will load an FFFFh into Timer/Counter 2. In either event a reload will set the TF2 bit.
A reload will also toggle the EXF2 bit. However, the EXF2 bit can not generate an interrupt while in
this mode.
Down Counting Reload Value
0FFh
0FFh
T2M = CKCON.5
C/T = T2CON.1
1/4
1
ptd
0
.7
T2CON
1/12
Timer 2
0
TL2
TH2
TF2
Interrupt
1
T2 = P1.0
TR2 = T2CON.2
RCAP2L
RCAP2H
Up Counting Reload Value
EXF2
T2EX = P1.1
DCEN = 1
T2CON.6
Figure 16. 16-Bit Auto-reload Up/Down Counter
Baud Rate Generator Mode
The baud rate generator mode is enabled by setting either the RCLK or TCLK bits in T2CON register.
While in the baud rate generator mode, Timer/Counter 2 is a 16 bit counter with auto reload when the
count rolls over from FFFFh. However, rolling over does not set the TF2 bit. If EXEN2 bit is set, then a
negative transition of the T2EX pin will set EXF2 bit in the T2CON register and cause an interrupt
request.
Figure 17. Baud Rate Generator Mode
- 42 -