7480 datasheet(222/337 Pages) RENESAS

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7480 Group and 7481 Group User's Manual

2-7

APPLICATIONS

Figure 2.2.5 Control Procedure Example of Measuring Water Flow Rate

2.2 Timer X and Timer Y

Set timer X mode register

TXM(Address 00F616)

Timer • event count mode

Writing to latch and timer simultaneously

Flow rate measuring routine

Timer X interrupt enable bit

← 1

Timer X

← C34F16 (Note 2)

Set timer XY control register

×× 00 00

TXYCON(Address 00F816)

Timer X count start

Set timer XY control register

TXYCON(Address 00F816)

Timer X count stop

Timer Y count stop

Timer X interrupt enable bit

← 0

Timer Y interrupt enable bit

← 0

Set timer Y mode register

TYM(Address 00F716)

Timer • event count mode

Writing to latch and timer simultaneously

00 0

Timer Y

← FFFF16 (Note 1)

Timer Y count start

END

RTI

Set timer XY control register

TXYCON(Address 00F816)

Timer X count stop

Timer Y count stop

Timer X interrupt service routine

Timer Y is read out (Note 3).

Timer X interrupt request bit

← 0

Timer Y interrupt request bit

← 0

Timer Y count source: CNTR1 pin input

Timer X count source: f(XIN)/16

CNTR1 edge selection bit

← 0

(counting rising edges)

Note 1: • Initial value.

• Write to timer Y in order of low-order to high-order byte.

2: • C34F16 = 50000 – 1.

• Write to timer X in order of low-order to high-order byte.

3: • (FFFF16 – the read value of Timer Y) = the number of CNTR1

edges detected during 100 ms.

• Read from timer Y in order of high-order to low-order byte.

Port P41 (alternative function of CNTR1) is set to input.

××

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