C509-L_97 Datasheet, PDF (112/290 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

On-Chip Peripheral Components
C509-L
The bits T2PS, T2PS1, T2P1, and T2P0 are prescaler select bits. T2R1 and T2R0 select the reload
mode. T2I1 and T2I0 select the clock input source of timer 2. Bits ET2, EXEN2, EXF2, and TF2 are
interrupt control bits/flags. Detailed bit definition is given in the table below.
Bit
T2PS
T2P1
T2P0
T2PS1
T2R1
T2R0
T2I1
T2I0
ET2
Symbol
Timer 2 prescaler select bits
Based on f_OSC/6 these bits define the prescaler divider ratio of the timer 2
input clock according the following table.
T2P1
0
0
0
0
1
1
1
1
T2P0
0
0
1
1
0
0
1
1
T2PS1
0
1
0
1
0
1
0
1
Timer 2
Input Clock
T2PS=0
f_OSC ÷ 6
f_OSC ÷ 24
f_OSC ÷ 12
f_OSC ÷ 48
f_OSC ÷ 24
f_OSC ÷ 96
f_OSC ÷ 48
f_OSC ÷ 192
Timer 2
Input Clock
T2PS=1
f_OSC ÷ 12
f_OSC ÷ 48
f_OSC ÷ 24
f_OSC ÷ 96
f_OSC ÷ 48
f_OSC ÷ 192
f_OSC ÷ 96
f_OSC ÷ 384
Timer 2 reload mode selection
T2R1
0
1
1
T2R0
X
0
1
Reload Mode
Reload disabled
Mode 0: auto-reload upon timer 2 overflow (TF2)
Mode 1: reload upon falling edge at pin P1.5 / T2EX
Timer 2 input selection
T2I1
0
0
1
1
T2I0
0
1
0
1
Input Mode
No input selected : timer 2 stops
Timer function : input frequency see table above
Counter function : external input controlled by pin
P1.7 / T2
Gated timer functiol : input controlled by pin T2/P1.7
Timer 2 Interrupt Enable.
If ET2 = 0, the timer 2 interrupt is disabled.
Semiconductor Group
6-34
1997-10-01