UPD17708 datasheet(283/356 Pages) NEC

No. de pieza	UPD17708

Descripción Electrónicos	4-BIT SINGLE-CHIP MICROCONTROLLERS WITH DEDICATED HARDWARE FOR DIGITAL TUNING SYSTEM

PDF	356 Pages

Scroll/Zoom	100%

Fabricante Electrónico	NEC [NEC]

Página de inicio	http://www.nec.com/

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283 / 356 page

283

µPD17704, 17705, 17707, 17708, 17709

18.4 Using IF Counter

The following sections 18.4.1 through 18.4.3 describe how to use the hardware of the IF counter, a program

example, and count error.

18.4.1 Using hardware of IF counter

Figure 18-9 shows the block diagram when the P1C0/FMIFC and P1C1/AMIFC pins.

As shown in the figure, the IF counter uses an input pin with an AC amplifier, the DC component of the input signal

must be cut with a capacitor.

When the P1C0/FMIFC or P1C1/AMIFC pin is selected for the IF counter function, switch SW turns ON, and the

voltage level on each pin reaches about 1/2VDD.

If the voltage has not risen to a sufficient intermediate level at this time, the IF counter does not operate normally

because the AC amplifier is not in the normal operating range.

Therefore, make sure that a sufficient wait time elapses after each pin has been specified to be used for the IF

counter until counting is started.

Figure 18-9. IF Count Function Block Diagram of Each Pin

To internal counter

FMIFC

AMIFC

External frequecny

UPD17708 Datasheet(PDF) 283 Page - NEC