Name

ID

Command Code

D/C

Function

Def.

F1

100 101X-0000-X

C

Time base clock output: 1Hz

The WDT time-out flag after: 4s

F2

100 101X-0001-X

C

Time base clock output: 2Hz

The WDT time-out flag after: 2s

F4

100 101X-0010-X

C

Time base clock output: 4Hz

The WDT time-out flag after: 1s

F8

100 101X-0011-X

C

Time base clock output: 8Hz

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

F16

100 101X-0100-X

C

Time base clock output: 16Hz

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

F32

100 101X-0101-X

C

Time base clock output: 32Hz

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

F64

100 101X-0110-X

C

Time base clock output: 64Hz

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

F128

100 101X-0111-X

C

Time base 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

Notes: 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 except for the

first command will be omitted. The source of the tone frequency and of the time base/WDT clock fre-

quency can be derived from a 32.768kHz crystal oscillator. Calculation of the frequency is based on

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

tialize the HT1620 after power on reset, for power on reset may fail, which in turn leads to malfunc-

tioning of the HT1620.

HT1620

16

July 26, 1999