HT1621
Application Circuits
Host Controller with an HT1621 Display System
*
M C U
*
R
C S
R D
W R
D A T A
V D D
*
V L C D
V R
H T 1 6 2 1 B
B Z
P ie z o
B Z
IR Q
O S C I
C lo c k O u t
E x te r n a l C o lc k 1
E x te r n a l C o lc k 2
O n - c h ip O S C
C ry s ta l
3 2 7 6 8 H z
1 /2 o r 1 /3 B ia s ; 1 /2 , 1 /3 o r 1 /4 D u ty
O S C O
C O M 0 ~ C O M 3
S E G 0 ~ S E G 3 1
L C D
P a n e l
Note:
The connection of IRQ and RD pin can be selected depending on the requirement of the MCU.
The voltage applied to V
LCD
pin must be lower than V
DD
.
Adjust VR to fit LCD display, at V
DD
=5V, V
LCD
=4V, VR=15kW±20%.
Adjust R (external pull-high resistance) to fit user’s time base clock.
Command Summary
Name
READ
WRITE
READ-MODIFY-
WRITE
SYS DIS
SYS EN
LCD OFF
LCD ON
TIMER DIS
WDT DIS
TIMER EN
WDT EN
TONE OFF
TONE ON
CLR TIMER
CLR WDT
XTAL 32K
ID
110
101
101
100
100
100
100
100
100
100
100
100
100
100
100
100
Command Code
A5A4A3A2A1A0D0D1D2D3
A5A4A3A2A1A0D0D1D2D3
A5A4A3A2A1A0D0D1D2D3
0000-0000-X
0000-0001-X
0000-0010-X
0000-0011-X
0000-0100-X
0000-0101-X
0000-0110-X
0000-0111-X
0000-1000-X
0000-1001-X
0000-11XX-X
0000-111X-X
0001-01XX-X
D/C
D
D
D
C
C
C
C
C
C
C
C
C
C
C
C
C
Function
Read data from the RAM
Write data to the RAM
READ and WRITE to the RAM
Turn off both system oscillator and LCD
Yes
bias generator
Turn on system oscillator
Turn off LCD bias generator
Turn on LCD bias generator
Disable time base output
Disable WDT time-out flag output
Enable time base output
Enable WDT time-out flag output
Turn off tone outputs
Turn on tone outputs
Clear the contents of time base generator
Clear the contents of WDT stage
System clock source, crystal oscillator
Yes
Yes
Def.
Rev. 1.30
12
August 6, 2003
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
