TMP86CS44UG datasheet(84/172 Pages) TOSHIBA

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Page 74

8. 16-Bit TimerCounter 1 (TC1)

8.3 Function

TMP86CS44UG

8.3.5 Pulse Width Measurement Mode

In the pulse width measurement mode, the up-counter starts counting by the input pulse triggering of the

TC1 pin, and counts up at the edge of the internal clock. Either the rising or falling edge of the internal clock is

selected as the trigger edge in TC1CR<TC1S>. Either the single- or double-edge capture is selected as the trig-

ger edge in TC1CR<MCAP1>.

• When TC1CR<MCAP1> is set to “1” (single-edge capture)

Either high- or low-level input pulse width can be measured. To measure the high-level input pulse

width, set the rising edge to TC1CR<TC1S>. To measure the low-level input pulse width, set the

falling edge to TC1CR<TC1S>.

When detecting the edge opposite to the trigger edge used to start counting after the timer starts,

the up-counter captures the up-counter value into TC1DRB and generates an INTTC1 interrupt

request. The up-counter is cleared at this time, and then restarts counting when detecting the trigger

edge used to start counting.

• When TC1CR<MCAP1> is set to “0” (double-edge capture)

The cycle starting with either the high- or low-going input pulse can be measured. To measure the

cycle starting with the high-going pulse, set the rising edge to TC1CR<TC1S>. To measure the cycle

starting with the low-going pulse, set the falling edge to TC1CR<TC1S>.

When detecting the edge opposite to the trigger edge used to start counting after the timer starts,

the up-counter captures the up-counter value into TC1DRB and generates an INTTC1 interrupt

request. The up-counter continues counting up, and captures the up-counter value into TC1DRB and

generates an INTTC1 interrupt request when detecting the trigger edge used to start counting. The

up-counter is cleared at this time, and then continues counting.

Note 1: The captured value must be read from TC1DRB until the next trigger edge is detected. If not read, the cap-

tured value becomes a don’t care. It is recommended to use a 16-bit access instruction to read the captured

value from TC1DRB.

Note 2: For the single-edge capture, the counter after capturing the value stops at “1” until detecting the next edge.

Therefore, the second captured value is “1” larger than the captured value immediately after counting

starts.

Note 3: The first captured value after the timer starts may be read incorrectively, therefore, ignore the first captured

value.

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