Freescale Semiconductor, Inc.
Enhanced Capture Timer
Enhanced Capture Timer Modes of Operation
If the corresponding NOVWx bit of the ICOVW register is set, the capture
register cannot be written unless it is empty.
This will prevent the captured value to be overwritten until it is read.
14.3.1.2 Buffered IC Channels
There are two modes of operations for the buffered IC channels.
IC Latch Mode:
•
When enabled (LATQ=1), the main timer value is memorized in the IC
register by a valid input pin transition.
The value of the buffered IC register is latched to its holding register by
the Modulus counter for a given period when the count reaches zero, by
a write $0000 to the modulus counter or by a write to ICLAT in the
MCCTL register.
If the corresponding NOVWx bit of the ICOVW register is cleared, with a
new occurrence of a capture, the contents of IC register are overwritten
by the new value. In case of latching, the contents of its holding register
are overwritten.
If the corresponding NOVWx bit of the ICOVW register is set, the capture
register or its holding register cannot be written by an event unless they
are empty (see IC Channels). This will prevent the captured value to be
overwritten until it is read or latched in the holding register.
•
IC Queue Mode:
When enabled (LATQ=0), the main timer value is memorized in the IC
register by a valid input pin transition.
If the corresponding NOVWx bit of the ICOVW register is cleared, with a
new occurrence of a capture, the value of the IC register will be
transferred to its holding register and the IC register memorizes the new
timer value.
If the corresponding NOVWx bit of the ICOVW register is set, the capture
register or its holding register cannot be written by an event unless they
are empty (see IC Channels).
68HC(9)12D60 — Rev 4.0
MOTOROLA
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Enhanced Capture Timer
205
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