User manual

read with and without lighting. This makes them unlit, but a
little dimmer than a reflective version. Nevertheless, it is
probably the best compromise for lit LCDs. Transmissive displays
have no reflector at all. They can only be read with lighting
but are very bright. The LCD in the learning package is a
transflective LCD.
5.5 | The Controller of the LC-Display
Dot-matrix-displays are produced by many manufacturers around
the world (and particularly in Taiwan). In addition to displays
from large providers like Data-Vision, there are also displays
of which the manufacturer cannot be determined at all. Luckily,
the function and connection of the displays are always the same.
In this learning package, we will deal with displays that use
a controller type HD44780 (or compatible), e.g. the KS0066.
The consistent behaviour of all displays is due to a controller
chip that has become established as the standard and that is
installed by all manufacturers. This is the HD44780 by Hitachi.
5.6 | This is How the Display is Controlled by the Display Controller
The following figures show how the display controller (KS0066)
is connected to the display. These circuits do not need to be
performed by you. They are already present on the LCD modules.
The controllers are partially differently connected to the
displays and may also be switched differently depending on
manufacturer. Thus, it is possible that a single-line
16-character display is made up of 2 x 8 characters. You need
to check the data sheet for this. Larger displays also often use
two controller chips that have a Chipselect- (CS) or two Enable
lines. The reason for this is that a controller only has a
character buffer of 80 characters. By connecting several display
controllers, the character buffer will increase by another 80
characters each. The displays also have another connection and
are relatively easy to distinguish from the stand-
ard-LCD-modules. It can be assumed that a display without
lighting has 14 pins and one with lighting has 16 pins.
5.7 | The Contrast Setting of the Display
As in other screens, we can set the contrast for LCD-modules as
well. This is done, e.g., with a 10-kΩ-potentiometer, that is
switched as a variable voltage distributor. Since the LCDs have