TMP93CS44 datasheet(121/224 Pages) TOSHIBA

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TMP93CS44/S45

2004-02-10

93CS44-119

3. Pulse width measurement

This mode allows to measure the “H” level width of an external pulse. While

keeping the 16-bit timer/event counter counting (Free running) with the internal

clock input, the external pulse is input through the TI4 pin. Then the capture

function is used to load the UC4 values into CAP1 and CAP2 at the rising edge

and falling edge of the external trigger pulse respectively. The interrupt INT4

occurs at the falling edge of TI4.

The pulse width is obtained from the difference between the values of CAP1 and

CAP2 and the internal clock cycle.

For example, if the internal clock is 0.8 microseconds and the difference

between CAP1 and CAP2 is 100, the pulse width will be 100

× 0.8 µs = 80 µs.

Additionally, the pulse width which is over the UC4 maximum count time

specified by the clock source can be measured by changing software.

Figure 3.8.16 Pulse Width Measurement

Note:

Only in this pulse width measuring mode (T4MOD<CAP12M1:0>

= 10),

external interrupt INT4 occurs at the falling edge of TI4 pin input. In other

modes, it occurs at the rising edge.

The width of “L” level can be measured by multiplying the difference between

the first C2 and the second C1 at the second INT interrupt and the internal clock

cycle together. See Figure 3.8.17 “Time Difference Measurement”.

TI4 pin (External pulse)

Loading UC16 into CAP1

Count clock

(Internal clock)

Loading UC16 into CAP2

INT4

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