TMP86FS23UG datasheet(97/252 Pages) TOSHIBA

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Page 85

TMP86FS23UG

8.3.3 Pulse Width Measurement mode

In this mode, pulse widths are counted on the falling edge of logical AND-ed pulse between ECIN pin input

(window pulse) and the internal clock. When using this mode, set TC1CR1<TC1CK> to suitable internal clock

and then set TC1CR2<SEG> to “0” (Both edges can not be used).

An INTTC1 interrupt is generated when the ECIN input detects the falling edge of the window pulse or both

rising and falling edges of the window pulse, that can be selected by TC1CR2<SGEDG>.

The contents of TREG1A should be read while the count is stopped (ECIN pin is low), then clear the counter

using TC1CR1<TC1C> (Normally, execute these process in the interrupt program).

When the counter is not cleared by TC1CR1<TC1C>, counting-up resumes from previous stopping value.

When up counter is counted up from 3FFFFH to 00000H, an overflow occurs. At that time, TC1SR<HEOVF>

is set to “1”. TC1SR<HEOVF> remains the previous data until the counter is required to be cleared by

TC1CR1<TC1C>.

Note:In pulse width measurement mode, if TC1CR1<TC1S> is written to "00" while ECIN input is "1", INTTC1 inter-

rupt occurs. According to the following step, when timer counter is stopped, INTTC1 interrupt latch should be

cleared to "0".

Note 1: When SGEDG (window gate pulse interrupt edge select) is set to both edges and ECIN pin input is "1" in

the pulse width measurement mode, an INTTC1 interrupt is generated by setting TC1S (TC1 start control)

to "10" (start).

Note 2: In the pulse width measurement mode, HECF (operating status monitor) cannot used.

Note 3: Because the up counter is counted on the falling edge of logical AND-ed pulse (between ECIN pin input and

the internal clock), if ECIN input becomes falling edge while internal source clock is "H" level, the up

counter stops plus "1".

Figure 8-4 Pulse width measurement mode timing chart

Example :

TC1STOP :

; Clear IMF

CLR

(EIRL). 7

; Clear bit7 of EIRL

(TC1CR1), 00011010B

; Stop timer couter 1

(ILL), 01111111B

; Clear bit7 of ILL

SET

(EIRL). 7

; Set bit7 of EIRL

; Set IMF

n-2

n-1

n+1

ECIN pin input

INTTC1 interrupt

Internal clock

AND-ed pulse

(Internal signal)

Up counter

TC1CR1<TC1C>

Interrupt

Read Clear

Count Start

Count Stop

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