Liquid Crystal Displays
or
LCDs
are cheap and
popular way of representing information to the
end user of some electronic device. Character
LCDs can be used to represent standard and
custom characters in the predefined number of
fields. EasyAVR
™
v7 provides the connector and the
necessary interface for supporting
2x16 character
LCDs
in 4-bit mode. This type of display has two rows
consisted of 16 character fields. Each field is a 7x5 pixel
matrix. Communication with the display module is done
through
CN8
display connector. Board is fitted with uniquely
designed plastic display distancer, which allows the LCD module
to perfectly and firmly fit into place.
GND and VCC
- Display power supply lines
Vo
- LCD contrast level from potentiometer P2
RS
- Register Select Signal line
E
- Display Enable line
R/W
- Determines whether display is in Read or Write mode. It’s
always connected to GND, leaving the display in Write mode all
the time.
D0–D3
- Display is supported in 4-bit data mode, so lower half of
the data byte interface is connected to GND.
D4–D7
- Upper half of the data byte
LED+
- Connection with the back-light LED anode
LED-
- Connection with the back-light LED cathode
We have allowed LCD back-light to be enabled in two different
ways:
1. It can be
turned on with full brightness
using
SW3.1
switch.
2. Brightness level can be determined
with PWM signal
from the
microcontroller, allowing you to write custom back-light controlling
software. This back-light mode is enabled with
SW3.2
switch.
LCD 2x16 characters
V
ss
V
dd
V
ee
R
S
R
/W
E
D
0
D
1
D
2
D
3
D
4
D
5
D
6
D
7
A
K
CN8
LCD SOCKET
VCC-5V
P2
10K
VCC-5V
Q5
BC846
R32
56
R37
4K7
R36
1K
VCC-BRD
VEE
G
N
D
G
N
D
G
N
D
G
N
D
G
N
D
G
N
D
PC
7
PC
6
PC
5
PC
4
PD6
PA2
BCK PWM
BCK LIGHT
1
2
3
4
5
6
7
8
O
N
SW3
PD5
VCC-5V
DATA BUS
LCD
BC
K PWM
Figure 10-1: On-board LCD 2x16 display connector
Figure 10-2: 2x16 LCD
connection schematic
Standard and PWM-driven back-light
Connector pinout explained
Make sure to turn off the power supply before placing LCD onto
the board. Otherwise your display can be permanently damaged.
In order to use PWM back-light both
SW3.1
and
SW3.2
switches must
be enabled at the same time.
IMPORTANT:
IMPORTANT:
page 20
displa
ys
Easy
AVR
v7
