EM73866 datasheet(26/39 Pages) EMC

26 / 39 page

* This specification are subject to be changed without notice.

EM73866

4-BIT MICRO-CONTROLLER FOR LCD PRODUCT

12.29.1999

RESETTING FUNCTION

When CPU in normal working condition and RESET pin holds in low level for three instruction cycles at least,

then CPU begins to initialize the whole internal states, and when RESET pin changes to high level, CPU begins

to work in normal condition.

The CPU internal state during reset condition is as following table :

Hardware condition in RESET state

Initial value

Program counter

0000h

Status flag

01h

Interrupt enable flip-flop ( EI )

00h

MASK0 ,1, 2, 3

00h

Interrupt latch ( IL )

00h

P10, 11,14, 16, 19, 21, 22, 25, 27, 28, 29, 31

00h

P1, 3, 4, 5, 6, 7, 8

0Fh

Both oscillator

Start oscillation

The RESET pin is a hysteresis input pin and it has a pull-up resistor available by mask option.

The simplest RESET circuit is connect RESET pin with a capacitor to V

SS and a diode to VDD.

PROGRAM EXAMPLE

To enable WDT with 7x213/LXIN detection time.

LDIA

#0001B

OUTA P21

; set WDT detection time and clear WDT counter

RESET

EM73866 Fiches technique(PDF) 26 Page - ELAN Microelectronics Corp