Renesas H8S/2100 Series, Hardware Manual

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Section 12 16-Bit Duty Period Measurement Timer (TDP)
Rev. 1.00 Apr. 28, 2008 Page 348 of 994
REJ09B0452-0100
(3) Determination of External Event (TDPCYI) Stoppage
Stoppage for an external event (TDPCYI) can be determined from the timer overflow flag. There
are two types of such stoppage.
Stoppage for an external event can be considered to have occurred when the timer overflows
within the period from the start of cycle measurement mode to the detection of the first edge
(rising or falling, as selected by the POCTL bit in TDPCR1).
Figure 12.10 shows an example of the timing of this type of stoppage for an external event.
φ
TDPCYI
Start of measurement
TDPMDS
TWDMXOVF/TWDMNUDF/
TPDMXOVF/TPDMNUDF
TDPCNT
H'0000 H'FFFF H'0000 N H'0000 H'0001 H'0002
OVF
Stoppage for an external event can be determined.
Figure 12.10 Example of Timing for Stoppage for an External Event (1)
When any of the TWDMXOVF, TWDMNUDF, TPDMXOVF, and TPDMNUDF flags is set to 1
while the CPSPE bit in TDPCR1 is 1, cycle measurement stops. Thereafter, when the
corresponding flag is cleared, cycle measurement restarts. When the timer overflows before the
first edge is detected after the restart of cycle measurement, it is possible to determine stoppage for
an external event.
Figure 12.11 shows an example of the timing for this type of stoppage for an external event.
φ
TDPCYI
Start of measurement
CPSPE
TWDMXOVF/TWDMNUDF/
TPDMXOVF/TPDMNUDF
TDPCNT
H'5555 H'0000 H'FFFF H'0000 N H'0000 H'0001
OVF
Restart of measurement
Stoppage for an external event can be determined
Figure 12.11 Example of Timing for Stoppage for an External Event (2)