C511_1 Datasheet, PDF (59/128 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

On-Chip Peripheral Units
Note: P1.1/T2EX is sampled during S5P2 of every machine cycle. The next increment/decrement
of timer 2 will be done during S3P1 in the next cycle.
6.2.2.2 Capture Mode
In the capture mode there are two options selected by bit EXEN2 in SFR T2CON.
If EXEN2 = 0, timer 2 is a 16-bit timer or counter which upon overflow sets bit TF2 in SFR T2CON.
This bit can be used to generate an interrupt.
If EXEN2 = 1, timer 2 still does the above, but with added feature that a 1-to-0 transition at external
input T2EX causes the current value in TH2 and TL2 to be captured into RC2H and RC2L,
respectively. In addition, the transition at T2EX causes bit EXF2 in SFR T2CON to be set. The EXF2
bit, like TF2, can generate an interrupt. The capture mode is illustrated in figure 6-25.
Figure 6-25
Timer 2 in Capture Mode
The baud rate generator mode is selected by RCLK = 1 and/or TCLK = 1 in SFR T2CON. It will be
described in conjunction with the serial port.
Semiconductor Group
6-26