HD66712 Datasheet, PDF (23/88 Pages) Hitachi Semiconductor – Dot-Matrix Liquid Crystal Display Controller/Driver

HD66712U
Liquid Crystal Display Driver Circuit
The liquid crystal display driver circuit consists of 34 common signal drivers and 60 segment signal
drivers. When the character font and number of lines are selected by a program, the required common
signal drivers automatically output drive waveforms, while the other common signal drivers continue to
output non-selection waveforms.
Character pattern data is sent serially through a 60-bit shift register and latched when all needed data has
arrived. The latched data then enables the driver to generate drive waveform outputs.
Sending serial data always starts at the display data character pattern corresponding to the last address of
the display data RAM (DDRAM).
Since serial data is latched when the display data character pattern corresponding to the starting address
enters the internal shift register, the HD66712 drives from the head display.
Cursor/Blink Control Circuit
The cursor/blink (or white-black inversion) control is used to produce a cursor or a flashing area on the
display at a position corresponding to the location in stored in the address counter (AC).
For example (Figure 10), when the address counter is (08)H, a cursor is displayed at a position
corresponding to DDRAM address (08)H.
Scroll Control Circuit
The scroll control circuit is used to perform a smooth-scroll in the unit of dot. When the number of
characters to be displayed is greater than that possible at one time on the liquid crystal module, this
horizontal smooth scroll can be used to display all characters.
AC = (08)16
1 2 3 4 5 6 7 8 9 10 11
00 01 02 03 04 05 06 07 08 09 0A
Display position
DDRAM address
Cursor position
Figure 10 Cursor/Blink Display Example
386