In this article we will discuss about
various types of Lcds used in Robots. Lcds stand for Liquid crystal display. It
is an electronic display module, it has a wider application in many fields.Lcds
are used in robots also to display any message for the user. If we want to
display value of sensors or any other data, these Lcds work a lot there. In
short it helps in debugging hardware and software components of Robots. For
displaying text we need to use software.We can represent an a single character
through an array of pixels. We need eight bytes to update one character on the
screen. The two starting command bytes tell us the two locations and the other
six bytes are used for the character.
Here we will talk about different types of Lcds used in small robots.Lcds are
preferable as they are more economical and easily programmable.
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2x8 display
It is a high contrast Lcds which is either in blue or neutral in color. It is
HD44780 compatible with built in ASCII character set. It either four or eight bit data base interface. The other
advantage of it that it is simply plug into PCB directly. It has 14vpins out of which pin no. 1 and 2 are for voltage
supplies, Pin 1 is used for ground.Using 3rd pin we can set contrast as much as we need. Pin no.7 to 14 are for displaying data
only.These all as we know work on a set of commands,i.e.for example if we provide it code 0000000001 It gives command to
clear all the display and then want the cursor
to return to home position, The first two 00s are for RS and R/W. In this way we
have different sets for different instructions. Plus if we want to create our own character, we can do this as
well. This can be possible by command "CG RAM Address set", This command defines the ASCII code and bit line."Data
write"command defines line by line the new character.
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The Lcds panel requires instructions to
give the display and for initialization.Lcd has an instruction register, the
required instruction is sent to this register which gets controlled by register
select.
Register line is Hardware inverted thus When pin corresponding to register line
is low, Instruction register is selected and so if we want to sent instructions
it is low and We place a data byte on Data lines and then give command to Lcd to
read it. We use Enable line. Now what we do we just set 0 in our control
register so that we can get high to low transition on strobe line.
16x2 display
A 16x2 Lcd is used to display 16 characters per line. And in this way two lines.
This Lcd has two registers. One is command and another is Data. The command
register stores the command instructions given to the LCD.This is done to
initialize it. Another tasks such as clearing screen, controlling its display is
also done by command register while the data which is to be displayed on the
screen is stored in data register. This is good to know that if initialization
is done properly, we should increase the delays.16x2 works with every
microcontroller.
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As we can see in pin-description that pin 1 is grounded, pin 2 is for supply
voltage while pin3 is used to adjust contrast.
4x20 Lcd
This Lcd is used to display 20 characters in each line and like this one line of
20 characters it can display 4 lines, therefore, this LCD has four lines of 20
characters, with an LED backlight. It needs only 5v as power source. We prefer parallax serial Lcds as they can be very easily interfaced with microcontroller.
Conclusion
There are so many lcds which we can use as display,these are described just to give you knowledge about one of the many hardware components used in robotics. Still if there is any doubt regarding this topic, i would try to clear it.