HT46R71D Holtek Semiconductor, HT46R71D Datasheet - Page 24

• Manufacturer Part Number: HT46R71D
• Description: A/D with LCD Type 8-Bit MCU
• Manufacturer: Holtek Semiconductor

LCD Display Memory
The device provides an area of embedded data memory
for LCD display. This area is located from 40H to 49H of
the RAM at Bank 1. Bank pointer (BP; located at 04H of
the RAM) is the switch between the RAM and the LCD
display memory. When the BP is set as 1 , any data
written into 40H~49H will effect the LCD display. When
the BP is cleared to 0 or 1 , any data written into
40H~49H means to access the general purpose data
memory. The LCD display memory can be read and writ-
ten to only by indirect addressing mode using MP1.
When data is written into the display data area, it is auto-
matically read by the LCD driver which then generates
the corresponding LCD driving signals. To turn the dis-
play on or off, a 1 or a 0 is written to the correspond-
ing bit of the display memory, respectively. The figure
illustrates the mapping between the display memory
and LCD pattern for the device.
The LCD clock is driven by the IRC clock, which then
passes through a divider, the division ratio of which is
selected by configuration options to provide a range of
Rev. 1.00
LCD Driver Output (1/3 Duty, 1/2 Duty, R Type)
24
LCD frequencies from Int.RCOSC/3 to Int.RCOSC/4.
Note that the LCD frequency is controlled by configura-
tion options, which select the internal division ratio.
There are no internal registers associated with the
buzzer frequency.
LCD Driver Output
The output number of the device LCD driver can be
10 3 by configuration option (i.e., 1/ 2 duty or 1/3 duty).
The bias type LCD driver is R type only. The LCD driver
bias voltage can be 1/ 2 bias or 1/3 bias by option.
Display Memory
HT46R71D
January 9, 2006