HT56R66 Holtek Semiconductor Inc., HT56R66 Datasheet - Page 30

• Manufacturer Part Number: HT56R66
• Description: Tinypower Tm A/d Type With Lcd 8-bit Otp Mcu
• Manufacturer: Holtek Semiconductor Inc.

Display Memory
An area of Data Memory is especially reserved for use
for the LCD/LED display data. This data area is known
as the Display Memory. Any data written here will be au-
tomatically read by the internal display driver circuits,
which will in turn automatically generate the necessary
LCD or LED driving signals. Therefore any data written
into this Memory will be immediately reflected into the
actual display connected to the microcontroller.
As the Display Memory addresses overlap those of the
General Purpose Data Memory, it s stored in its own in-
dependent 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 Display Memory therefore re-
quires 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 40H, will result in operations to the Display
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 Display Memory Map diagrams
shows how the internal Display Memory is mapped to
the Segments and Commons of the display for the larg-
est device, which is the HT56R666. Display Memory
Maps for devices with smaller memory capacities can
be extrapolated from these diagrams.
Rev. 1.10
HT56R666 Memory Map - 48´16
30
The accompanying waveform diagrams show the gen-
erated waveforms for a range of duty and bias types.
The huge number of permutations of available for the
LCD and LED waveform types does not permit all types
to be depicted.
HT56R666 Memory Map - 56´8
HT56R66/HT56R666
September 8, 2009