W79E548 Datasheet, PDF (45/79 Pages) Winbond – 8-BIT MICROCONTROLLER

W79E548/W79L548
Auto-reload Mode, Counting Up/Down
Timer/Counter 2 will be in auto-reload mode as an up/down counter if CP / RL2 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.
T2M = CKCON.5
osc
1/4
C/T = T2CON.1
1
0
1/12 ₀
1
T2 = P1.0
TR2 = T2CON.2
Down Counting Reload Value
0FFh 0FFh
TL2 TH2
T2EX = P1.1
RCAP2L RCAP2H
Up Counting Reload Value
DCEN = 1
T2CON.7
TF2
Timer 2
Interrupt
EXF2
T2CON.6
Figure 16. 16-Bit Auto-reload Up/Down Counter
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Publication Release Date: December 12, 2005
Revision A1