HT82M99AE datasheet(13/47 Pages) HOLTEK

13 / 47 page

HT82M99EE/HT82M99AE

Rev. 1.00

February 8, 2006

by one or more cycles. If the wake-up results in the next

instruction execution, this will be executed immediately

after the dummy period is finished.

To minimize power consumption, all the I/O pins should

be carefully managed before entering the HALT status.

Reset

There are four ways in which a reset can occur:

· RES reset during normal operation

· RES reset during HALT

· WDT time-out reset during normal operation

· USB reset

The WDT time-out during HALT is different from other

chip reset conditions, since it can perform a

²warm re -

set

² that resets only the program counterand SP, leaving

the other circuits in their original state. Some registers

remain unchanged during other reset conditions. Most

registers are reset to the

²initial condition² when the re-

set conditions are met. By examining the PDF and TO

flags, the program can distinguish between different

²chip resets².

TO PDF

RESET Conditions

RES reset during power-up

RES reset during normal operation

RES wake-up HALT

WDT time-out during normal operation

WDT wake-up HALT

Note:

²u² stands for ²unchanged²

To guarantee that the system oscillator is started and

stabilized, the SST (System Start-up Timer) provides an

extra delay of 1024 system clock pulses when the sys-

tem resets (power-up, WDT time-out or RES reset) or

the system awakes from the HALT state.

When a system reset occurs, the SST delay is added

during the reset period. Any wake-up from HALT will en-

able the SST delay.

The functional unit chip reset status are shown below.

Program Counter

000H

Interrupt

Disable

Prescaler

Clear

WDT

Clear. After master reset,

WDT begins counting

Timer/event Counter

Off

Input/output Ports

Input mode

Stack Pointer

Points to the top of the stack

V D D

R E S

Reset Circuit

W a r m R e s e t

W D T

H A L T

C o l d

R e s e t

R E S

S y s t e m R e s e t

S S T

1 0 - b i t R i p p l e

C o u n t e r

O S C 1

Reset Configuration

t S S T

R E S

V D D

S S T T i m e - o u t

C h i p R e s e t

Reset Timing Chart

HT82M99AE Datasheet(PDF) 13 Page - Holtek Semiconductor Inc

HT82M99AE Datasheet(HTML) 13 Page - Holtek Semiconductor Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47

Datasheet Download

Link URL