C868_02 Datasheet, PDF (77/244 Pages) Infineon Technologies AG – 8 - Bit CMOS Microcontroller

C868
On-Chip Peripheral Components
4.7.1.2 Counting Rules
Referring to T12 input clock the counting sequence is defined by the following counting
rules:
T12 in edge-aligned mode:
• The counter is reset to zero and (if desired) the T12 shadow transfer takes place if the
period-match is detected. The counting direction is always upwards.
T12 in center-aligned mode:
• The count direction is set to counting up (CDIR=’0’) if the one-match is detected while
counting down.
• The count direction is set to counting down (CDIR=’1’) if the period-match is detected
while counting up.
• The counter counts up while CDIR=’0’ and it counts down while CDIR=’1’.
• If enabled the shadow transfer takes place:
• if the period-match is detected while counting up
• if the one-match is detected while counting down
The timer T12 prescaler is reset while T12 is not running to ensure reproducible timings
and delays.
The counting rules lead to the following sequences:
.
T12clk
T12P
T12P-1
T12P-2
period-match
zero-match
T12
1
0
up=0
CDIR
value n
Figure 4-11 T12 in edge-aligned mode
value n+1 CC6x
shadow transfer
User’s Manual
4-33
V 0.4, 2002-01