UPD17708 datasheet(170/356 Pages) NEC

170 / 356 page

µPD17704, 17705, 17707, 17708, 17709

170

(2) Gate counter mode

The gate counter mode is used to count the width of a pulse input to the TM0G pin.

An example of a program is shown below.

In this program example, the width of the pulse input to the TM0G pin is counted from the falling edge

to the falling edge.

If the pulse width is 800 to 1200

µs, processing C is executed; otherwise, processing B is executed.

If the pulse width is 2560

µs or more, processing D is executed.

TM0800

DAT

0050H

; Count data = 80

TM01200

DAT

0078H

; Count data = 120

START:

INITIAL

; Reset address

; Interrupt vector address

NOP

; SIO1

NOP

; SIO0

NOP

; TM3

NOP

; TM2

NOP

; TM1

INT_TM0

; TM0

NOP

; INT4

NOP

; INT3

NOP

; INT2

NOP

; INT1

NOP

; INT0

NOP

; Down edge of CE

INITIAL:

INITFLG

NOT TM0EN, TM0RES, NOT TM0CK1, NOT TM0CK0

;

(Stop)

, (Reset) ,

(Basic clock = 10

µs)

INITFLG

TM0GCEG ,

TM0GOEG ,

TM0MD

;

(Falling close), (Falling open), (Gate counter)

SET1

TM0EN

; START

SET1

IPTM0

; Enables timer 0 interrupt

LOOP:

Processing A

LOOP

INT_TM0:

PUT

DBFSTK, DBF

; Saves data buffer

GET

DBF, TM0C

INITFLG

TM0EN, TM0RES

SKT1

TM0OVF

; Detects overflow status (2560

µs or more?)

AAA

Processing D

EI_RETI

AAA:

SUB

DBF0, #TM0800 AND 0FH

SUBC

DBF1, #TM0800 SHR4 AND 0FH

SKF1

; 800

µs or more?

BBB

SUB

DBF0, #TM01200 AND 0FH

UPD17708 Datasheet(PDF) 170 Page - NEC

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