HT1647 datasheet(13/24 Pages) HOLTEK

13 / 24 page

HT1647

April 21, 2000

Time base and Watchdog Timer - WDT

The time base generator and WDT share the

same divided (/256) counter. The IRQ clock can be

programmed as 1Hz, 2Hz, ...., 128Hz output.

TIMER DIS/EN/CLR, WDT DIS/EN/CLR and

IRQ EN/DIS are independent from each other.

Once the WDT time-out occurs, the IRQ pin will

remain at a logic low level until the CLR WDT

or the IRQ DIS command is issued.

If an external clock is selected as the system

frequency source, the SYS DIS command turns

out invalid and the power down mode fails to be

carried out until the external clock source is re-

moved.

W D T E N /D IS

IR Q E N /D IS

CL R W D T

C l o ck S o u r ce

/ 256

Ti m e B a s e

CL R T i m e r

IR Q

WD T

V DD

TI M E R E N / D I S

Time base and WDT configurations

Name

Command Code

Function

TONE OFF

X100-0000-1000-XXXX

Turn-off tone output

TONE 4K

X100-0001-0000-XXXX

Turn-on tone output, tone frequency is 4kHz

TONE 2K

X100-0001-0001-XXXX

Turn-on tone output, tone frequency is 2kHz

Buzzer tone output command code

Buzzer tone output

A simple tone generator is implemented in the

HT1647. The tone generator can output a pair

of differential driving signals on the BZ and BZ

which are used to generate a single tone.

By executing the TONE 4K and TONE 2K com-

mands there are two tone frequency outputs

selectable and turn on tone output. The TONE

4K and TONE 2K commands set the tone fre-

quency to 4kHz and 2kHz, respectively. The

tone output can be turned off by invoking the

TONE OFF command. The tone outputs,

namely BZ and BZ, are a pair of differential

driving outputs used to drive a piezo buzzer.

Once the system is disabled or the tone output

is inhibited, the BZ and the BZ outputs will re-

main at low level.

Command format

The HT1647 can be configured by software set-

ting. There are two mode commands to config-

ure the HT1647 resource and to transfer the

LCD display data.

The configuration mode of the HT1647 is called

command mode, and its command mode ID is

100. The command mode consists of a system

configuration command, a system frequency se-

lection command, an LCD configuration com-

mand, a tone frequency selection command, a

bias current selection command, a gray scale

level selection command, a timer/WDT setting

command, and an operating command. The

data mode, on the other hand, includes READ,

WRITE, and READ-MODIFY-WRITE opera-

tions.

HT1647 Datasheet(PDF) 13 Page - Holtek Semiconductor Inc

HT1647 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

Datasheet Download

Link URL