C161 Datasheet, PDF (224/400 Pages) Infineon Technologies AG – 16-Bit Single-Chip Microcontroller

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GPT2 Capture/Reload Register CAPREL in Capture Mode
This 16-bit register can be used as a capture register for the auxiliary timer T5. This
mode is selected by setting bit T5SC=‘1’ in control register T5CON. Bit CT3 selects the
external input pin CAPIN or the input pins of timer T3 as the source for a capture trigger.
Either a positive, a negative, or both a positive and a negative transition at pin CAPIN
can be selected to trigger the capture function, or transitions on input T3IN or input
T3EUD or both inputs T3IN and T3EUD. The active edge is controlled by bit field CI in
register T5CON.
The maximum input frequency for the capture trigger signal at CAPIN is f_CPU/4. To
ensure that a transition of the capture trigger signal is correctly recognized, its level
should be held for at least 4 f_CPU cycles before it changes.
Input
Clock
CAPIN
T3IN/
T3EUD
MUX
CT3
Edge
Select
CI
Up/Down
Auxiliary Timer T5
Interrupt
Request
T5CLR
T5SC
CAPREL Register
Interrupt
Request
MCB02044B.VSD
Figure 10-19 GPT2 Register CAPREL in Capture Mode
When the timer T3 capture trigger is enabled (CT3=’1’) register CAPREL captures the
contents of T5 upon transitions of the selected input(s). These values can be used to
measure T3’s input signals. This is useful e.g. when T3 operates in incremental interface
mode, in order to derive dynamic information (speed acceleration) from the input signals.
User’s Manual
10-32
1999-08