C868_02 Datasheet, PDF (88/244 Pages) Infineon Technologies AG – 8 - Bit CMOS Microcontroller

C868
On-Chip Peripheral Components
be selected as capture event, that is used to transfer the contents of timer T12 to the
CC6xR and CC6xSR registers. In order to work in capture mode, the capture pins have
to be configured as inputs.
CC6x_in
fper
in
R
edge
detection
F
Capt_re
Capt_fe
function
select
tr_T_R
tr_T_SR
tr_SR_R
MSEL6x
Figure 4-23 Capture Logic
The block diagram of the capture logic for one channel is shown in Figure 4-23. This
logic is identical for all three independent channels of timer T12. The input signal
(CC6x_in) from the input pin CC6x is connected to an edge detection logic delivering two
output signals, one for the rising edge (Capt_re) and one for the falling edge (Capt_fe).
These signals are also used as trigger sources for the channel interrupts if capture mode
is selected.
There are several possibilities to store the captured values in the registers. In double
register capture mode the timer value is stored in the channel shadow register CC6xSR.
The value formerly stored in this register is simultaneously copied to the channel register
CC6xR.This mode can be used if two capture events occur with very few time between
them. The SW can then check the new captured value and has still the possibility to read
the value captured before.
The selection of the capture mode is done by bitfield MSEL6x. According to the selected
mode and the detected capture event, the signals tr_T_R (transfer T12 contents to
register CC6xR), tr_T_SR (transfer T12 contents to register CC6xSR) or tr_SR_R
(transfer contents of CC6xSR to register CC6xR) are activated.
Note: In capture mode, a shadow transfer can be requested according to the shadow
transfer rules, except for the capture / compare registers, that are left unchanged.
4.7.1.10 Single Shot Mode
In single shot mode, the timer T12 stops automatically at the end of the its counting
period. Figure 4-24 shows the functionality at the end of the timer period in edge-aligned
User’s Manual
4-44
V 0.4, 2002-01