W77E058A40DL Datasheet, PDF (56/87 Pages) Nuvotem Talema – GENERAL DESCRIPTION

W77E058A
12.3 Timer/Counter 2
Timer/Counter 2 is a 16 bit up/down counter which is configured by the T2MOD register and controlled
by the T2CON register. Timer/Counter 2 is equipped with a capture/reload capability. As with the
Timer 0 and Timer 1 counters, there exists considerable flexibility in selecting and controlling the clock,
and in defining the operating mode. The clock source for Timer/Counter 2 may be selected for either
the external T2 pin (C/T2 = 1) or the crystal oscillator, which is divided by 12 or 4 (C/T2 = 0). The clock
is then enabled when TR2 is a 1, and disabled when TR2 is a 0.
Clock Source
Mode input
div. by 4 osc/1
div. by 64 osc/16
div. by 1024 osc/256
T0 = P3.4
TR0 = TCON.4
T0M = CKCON.3
1/4
1
C/T = TMOD.2
0
1/12 0
1
GATE = TMOD.3
INT0 = P3.2
TR1 = TCON.6
TL0
0
7
TH0
0
7
TF0
Interrupt
TF1
Interrupt
Figure 13. Timer/Counter 0 Mode 3
12.3.1 Capture Mode
The capture mode is enabled by setting the CP / RL2 bit in the T2CON register to a 1. In the capture
mode, Timer/Counter 2 serves as a 16 bit up counter. When the counter rolls over from FFFFh to
0000h, the TF2 bit is set, which will generate an interrupt request. If the EXEN2 bit is set, then a
negative transition of T2EX pin will cause the value in the TL2 and TH2 register to be captured by the
RCAP2L and RCAP2H registers. This action also causes the EXF2 bit in T2CON to be set, which will
also generate an interrupt. Setting the T2CR bit (T2MOD.3), the W77E058 allows hardware to reset
timer 2 automatically after the value of TL2 and TH2 have been captured.
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