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Rev. 1.20
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Rev. 1.20
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HT69F30A/HT69F40A/HT69F50A
TinyPower
TM
I/O Flash 8-Bit MCU with LCD & EEPROM
HT69F30A/HT69F40A/HT69F50A
TinyPower
TM
I/O Flash 8-Bit MCU with LCD & EEPROM
LCD Driver
For large volume applications, which incorporate an LCD in their design, the use of a custom
display rather than a more expensive character based display reduces costs significantly. However,
the corresponding COM and SEG signals required, which vary in both amplitude and time, to drive
such a custom display require many special considerations for proper LCD operation to occur.
These devices all contain an LCD Driver function, which with their internal LCD signal generating
circuitry and various options, will automatically generate these time and amplitude varying signals
to provide a means of direct driving and easy interfacing to a range of custom LCDs.
All devices include a wide range of options to enable LCD displays of various types to be driven.
The table shows the range of options available across the device range.
Device
Duty
Bias
Bias Type
Wave Type
HT69F30A
1/3 o� 1/4
1/2 o� 1/3
R o� C
A o� B
HT69F40A
HT69F�0A
LCD Selections
LCD Memory
An area of Data Memory is especially reserved for use for the LCD display data. This data area
is known as the LCD Memory. Any data written here will be automatically read by the internal
display driver circuits, which will in turn automatically generate the necessary LCD driving signals.
Therefore any data written into this Memory will be immediately reflected into the actual display
connected to the microcontroller.
As the LCD Memory addresses overlap those of the General Purpose Data Memory, it s stored in
its own independent Bank 1 area. The Data Memory Bank to be used is chosen by using the Bank
Pointer, which is a special function register in the Data Memory, with the name, BP. To access the
LCD Memory therefore requires first that Bank 1 is selected by writing a value of 01H to the BP
register. After this, the memory can then be accessed by using indirect addressing through the use
of Memory Pointer MP1. With Bank 1 selected, then using MP1 to read or write to the memory
area, starting with address “80H” for all the devices, will result in operations to the LCD Memory.
Directly addressing the Display Memory is not applicable and will result in a data access to the
Bank 0 General Purpose Data Memory.
The accompanying LCD Memory Map diagrams shows how the internal LCD Memory is mapped
to the Segments and Commons of the display for the devices. LCD Memory Maps for devices with
smaller memory capacities can be extrapolated from these diagrams.