TMP88CU74F datasheet(76/132 Pages) TOSHIBA

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TMP88CU74

2003-02-17

88CU74-76

(3) Capture mode

The pulse width, period and duty of the TC3 pin input are measured in this mode,

which can be used in decoding the remote control signals or distinguishing AC 50/60

Hz, etc. The counter is free running by the internal clock. On the rising (falling) edge of

the TC3 pin input, the current contents of counter is loaded into TREG3A, then the

up-counter is cleared to “0” and an INTTC4 interrupt is generated. On the falling

(rising) edge of the TC3 pin input, the current contents of the counter is loaded into

TREG3B. In this case, counting continues. On the next rising (falling) edge of the TC3

pin input, the current contents of counter are loaded into TREG3A, then the counter is

cleared again and an interrupt is generated. If the counter overflows before the edge is

detected. FFH is set into TREG3A, and the counter is cleared and an INTTC3 interrupt

is generated. During interrupt processing, it can be determined whether or not there is

an overflow by checking whether or not the TREG3A value is FFH. Also, after an

interrupt (capture to TREG3A, or overflow detection) is generated, capture and

overflow detection are halted until TREG3A has been read out; however, the counter

continues. As reading out TREG3A resumes capture/overflow detection, TREG3B must

be beforehand read out.

Figure 2.8.3 Capture Mode Timing Chart (at INT4ES

= 0)

−1

Source clock

Up-counter

TC3 pin input

TREG3A

− 2

−1

Overflow

FF (Overflow)

−1 k 0

FE FF

Capture

TREG3B

INTTC3 interrupt

Reading TREG3A

2007-10-19

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