No. 5544-8/14

LC72P366

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Pin No.

Symbol

I/O

I/O type

Function

70

69

68

HCTR

LCTR

SNS

I

I

I

Input

Input

Input

Universal counter/general-purpose input shared-function input port

The IOS instruction b3 with PWn = 3 switches the pin function between universal counter

input and general-purpose input.

• Frequency measurement

The universal counter function is selected by an IOS instruction with PWn = 3 and b3 = 0.

HCTR frequency measurement mode is set up by a UCS instruction with b3 = 0 and b2 =

0, and counting is started with a UCC instruction after the count time is selected.

The CNTEND flag is set when the count completes.

To operate this circuit as an AC amplifier in this mode, the input must be capacitor

coupled.

• General-purpose input pin use

The general-purpose input port function is selected by an IOS instruction with PWn = 3

and b3 = 1.

An internal register (address: 0EH) input instruction INR (b0) is used to acquire data from

this pin.

Input is disabled in clock stop mode. (The input pin will be pulled down.)

During the power-on reset, the universal counter function is selected.

Universal counter (frequency and period measurement)/general-purpose input shared-

function input port

The IOS instruction b2 with PWn = 3 switches the pin function between universal counter

input and general-purpose input.

• Frequency measurement

The universal counter function is selected by an IOS instruction with PWn = 3 and b2 = 0.

LCTR frequency measurement mode is set up by a UCS instruction with b3 = 0 b2 = 1,

and counting is started with a UCC instruction after the count time is selected.

The CNTEND flag is set when the count completes.

To operate this circuit as an AC amplifier in this mode, the input must be capacitor

coupled.

• Period measurement

With the universal counter function selected, set up period measurement mode with a

UCS instruction with b3 = 1 and b2 = 0, and start the count with a UCC instruction after

selecting the count time. The CNTEND flag will be set when the count completes. In this

mode, the signal must be input with DC coupling to turn off the bias feedback resistor.

• General-purpose input pin use

The general-purpose input port function is selected by an IOS instruction with PWn = 3,

b2 = 1.

An internal register (address: 0EH) input instruction INR (b1) is used to acquire data from

this pin.

Input is disabled in clock stop mode. (The input pin will be pulled down.)

During the power-on reset, the universal counter function (in HCTR frequency

measurement mode) is selected.

Voltage sense/general-purpose input pin shared-function port

This circuit is designed for a relatively low input threshold voltage.

• Voltage sense pin usage

This input pin is used to determine whether or not a power failure occurred after recovery

from backup (clock stop) mode. An internal sense F/F is used for this determination. The

sense F/F is tested with a TUL instruction (b2).

• General-purpose input port usage

When used as a general-purpose input port, the state is sensed by using a TUL

instruction (b3).

Since, unlike other input ports, input is not disabled in clock stop mode and during the

power-on reset, special care is required with respect to through currents.