Lcd Clock Source; Lcd Register - Holtek HT67F2350 Manual

HT67F2350/HT67F2360
HT67F2370/HT67F2390
Advanced A/D Flash MCU with LCD & EEPROM

LCD Clock Source

The LCD clock source is the internal clock signal, f
circuit. The f internal clock is supplied by either the LIRC or LXT oscillator, the choice of which
SUB
is determined by a software control bit. For proper LCD operation, this arrangement is provided to
generate an ideal LCD clock source frequency of 4 kHz.

LCD Register

There are control registers, named as LCDC0, LCDC1 and LCDC2, in the Data Memory which is
used to control the various setup features of the LCD Driver.
Various bits in these registers control functions such as LCD wave type, bias type, supply power
selection, total bias resistor selection together with the overall LCD enable and disable control.
The LCDEN bit in the LCDC0 register, which provides the overall LCD enable/disable function,
will only be effective when the device is in the FAST, SLOW or IDLE Mode. If the device is in
the SLEEP Mode then the display will always be disabled. Bits, RSEL2 ~ RSEL0, in the LCDC0
register select the internal total bias resistors to supply the LCD panel with the proper bias current.
A choice to best match the LCD panel used in the application can be selected also to minimise
bias current. The TYPE bit in the LCDC0 register is used to select whether Type A or Type B LCD
waveform signals are used. The RCT bit in the same register is used to select whether R Type or C
Type LCD bias is used. The LCDP1 and LCDP0 bits are used to select that the LCD supply power
comes from either the external pin or internal power supply for C type bias application.
The PLCD3~PLCD0 bits in the LCDC1 register are used to select the V
circuitry. The QCT2~QCT0 bits in the same register are used to determine the quick charge time
period.
Register
Name
7
LCDC0 TYPE
LCDC1 QCT2
LCDC2 —
LCDC0 Register
Bit 7
Name TYPE
R/W R/W
POR 0
TYPE: LCD waveform type selection
Bit 7
0: Type A
1: Type B
Bit 6 RCT: LCD bias type selection
0: R type
1: C type
Bit 5~4 LCDP1~LCDP0: C type bias LCD power supply selection
00: From external pin PLCD, V1 or V2
01: From internal reference voltage V
10: From internal voltage V
11: From internal voltage V
The V
Rev. 1.60
6 5 4
RCT LCDP1 LCDP0
QCT1 QCT0 —
— — —
LCD Registers List
6 5 4
RCT LCDP1 LCDP0
R/W R/W R/W
0 0 0
supplied to VB
DD
supplied to VA
DD
is an internal reference voltage with an approximate level of 1.08V.
REFIN
225
, divided by 8 using an internal divider
SUB
voltage for R type bias
A
Bit
3 2 1
RSEL2 RSEL1 RSEL0
PLCD3 PLCD2 PLCD1
— DTYC1 DTYC0
3 2 1
RSEL2 RSEL1 RSEL0
R/W R/W R/W
0 0 0
supplied to VC
REFIN
0
LCDEN
PLCD0
BIAS
0
LCDEN
R/W
0
May 16, 2019