HT1621

19

April 21, 2000

Name

ID

Command Code

D/C

Function

Def.

IRQ EN

100 100X-1XXX-X

C Enable IRQ output

F1

100 101X-X000-X

C

Time base/WDT clock

output:1Hz

The WDT time-out flag after: 4s

F2

100 101X-X001-X

C

Time base/WDT clock

output:2Hz

The WDT time-out flag after: 2s

F4

100 101X-X010-X

C

Time base/WDT clock

output:4Hz

The WDT time-out flag after: 1s

F8

100 101X-X011-X

C

Time base/WDT clock

output:8Hz

The WDT time-out flag after: 1/2 s

F16

100 101X-X100-X

C

Time base/WDT clock

output:16Hz

The WDT time-out flag after: 1/4 s

F32

100 101X-X101-X

C

Time base/WDT clock

output:32Hz

The WDT time-out flag after: 1/8 s

F64

100 101X-X110-X

C

Time base/WDT clock

output:64Hz

The WDT time-out flag after: 1/16 s

F128

100 101X-X111-X

C

Time base/WDT clock

output:128Hz

The WDT time-out flag after: 1/32 s

Yes

TEST

100 1110-0000-X

C Test mode, user don't use.

NORMAL

100 1110-0011-X

C Normal mode

Yes

Note: X : Don

A5~A0 : RAM addresses

D3~D0 : RAM data

D/C : Data/command mode

Def. : Power on reset default

All the bold forms, namely 110, 101, and 100, are mode commands. Of these, 100 indicates

the command mode ID. If successive commands have been issued, the command mode ID ex-

cept for the first command will be omitted. The source of the tone frequency and of the time

base/WDT clock frequency can be derived from an on-chip 256kHz RC oscillator, a 32.768kHz

crystal oscillator, or an external 256kHz clock. Calculation of the frequency is based on the

system frequency sources as stated above. It is recommended that the host controller should

initialize the HT1621 after power on reset, for power on reset may fail, which in turn leads to

the malfunctioning of the HT1621.