HT1621B Datasheet, PDF (12/20 Pages) Holtek Semiconductor Inc – RAM Mapping 32x4 LCD Controller for I/O MCU

Application Circuits
Host Controller with an HT1621 Display System
HT1621
M CU
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
32768H z
CS
*
RD
VDD
WR
V LC D
D ATA
H T1621B
*_R
BZ
IR Q
O SCI
BZ
O SCO CO M 0 ~ CO M 3
S E G 0~S E G 31
1 /2 o r 1 /3 B ia s ; 1 /2 , 1 /3 o r 1 /4 D u ty
LC D P anel
*
VR
P ie z o
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
Command Code
D/C
Function
Def.
1 1 0 A5A4A3A2A1A0D0D1D2D3 D Read data from the RAM
1 0 1 A5A4A3A2A1A0D0D1D2D3 D Write data to the RAM
1 0 1 A5A4A3A2A1A0D0D1D2D3 D READ and WRITE to the RAM
1 0 0 0000-0000-X
1 0 0 0000-0001-X
1 0 0 0000-0010-X
1 0 0 0000-0011-X
1 0 0 0000-0100-X
1 0 0 0000-0101-X
1 0 0 0000-0110-X
1 0 0 0000-0111-X
1 0 0 0000-1000-X
1 0 0 0000-1001-X
1 0 0 0000-11XX-X
1 0 0 0000-111X-X
1 0 0 0001-01XX-X
C
Turn off both system oscillator and LCD
bias generator
Yes
C Turn on system oscillator
C Turn off LCD bias generator
Yes
C Turn on LCD bias generator
C Disable time base output
C Disable WDT time-out flag output
C Enable time base output
C Enable WDT time-out flag output
C Turn off tone outputs
Yes
C Turn on tone outputs
C Clear the contents of time base generator
C Clear the contents of WDT stage
C System clock source, crystal oscillator
Rev. 1.30
12
August 6, 2003