Holtek HT-IDE, User Manual, Page: 206 / 258

rows and then at the columns and making the appropriate steps through
the table values. In section (10) the table read instruction is used to
determine the displayed value of the individual key, which is then placed
on Port B which illuminates the corresponding LEDs.
LCM
This unit describes the use of an 8-bit microcontroller used in conjunction
with a DV16100NRB liquid crystal display. This LCM is driven and control-
led by an internal Hitachi HD44780 device. In this application only the
timing requirements of the LCM need to be considered to produce the
correct microcontroller signals. For more detailed timing and instruction
information, the LCM manufacturer’s data should be consulted first.
LCMs can operate in either 4 bit or 8 bit mode. Using a 4 bit mode of
operation, transmitting a character or an instruction to the module re-
quires two transmission events to complete the operation. With an 8-bit
mode of operation only one transmit event is required, however an extra 4
I/O lines are required. This section shows the use of the statements #define,
if, else and endif.
Circuit design
PB0~PB7 are setup as I/O bits while PC0~PC2 as the LCM control lines
are setup as outputs. These can be setup according to the specific user
requirements.
HT-IDE User’s Guide
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