Datasheet
One seven segment digit consist of 7+1
LEDs which are arranged in a specic
formation which can be used to represent
digits from 0 to 9 and even some letters.
One additional LED is used for marking
the decimal dot, in case you want to
write a decimal point in the desired
segment. EasyAVR
™
v7 contains four of
these digits put together to form 4-digit
7-segment display. Driving such a display
is done using multiplexing techniques.
Data lines are shared between segments,
and therefore the same segment LEDs in
each digit are connected in parallel. Each
digit has it’s unique digit select line,
which is used to enable the digit
to which the data is currently being
sent. By multiplexing data through all
four segments fast enough, you create
an illusion that all four segments are in
operation simultaneously.
This is possible because human eye has
a slower reaction time than the mention
changes. This way you can represent
numbers in decimal or hexadecimal form.
Eight data lines that are common for all
the digits are connected to PORTC, and
digit select lines are connected to PA0–
PA3 lines on the microcontroller sockets.
To enable digit select lines for the 4-digit
7-segment display you have to turn
on SW8.1, SW8.2, SW8.3 and SW8.4
switches. Digit select lines are connected
to PA0 – PA3 pins on the microcontroller
sockets, while data lines are connected to
PC0 – PC7 pins. Make sure to disconnect
other peripherals from the interface lines
in order not to interfere with signal/data
integrity.
1 2 3 4 5 6 7 8
O
N
SW8
R1 470
R2 470
R3 470
R4 470
R5 470
R6 470
R7 470
R11 470
Q4
BC846
Q3
BC846
Q2
BC846
Q1
BC846
R14
10K
R19
10K
R27
10K
R30
10K
COM3
COM0
COM1
COM2
DIS0
DIS1
DIS2
DIS3
PA1
PA3
PA2
PA0
DIS3
DIS0
DIS1
DIS2
seg E
seg D
seg C
seg DP
seg B
seg A
seg F
seg Q
PC7
PC6
PC4
PC3
PC2
PC1
PC0
PC5
DATA BUS
1
2
4
5 6
7
9
8
10
3
b
ac
d
e
f
g
dp
cc
1
2
4
5 6
7
9
8
10
3
b
ac
d
e
f
g
dp
cc
1
2
4
5 6
7
9
8
10
3
b
ac
d
e
f
g
dp
cc
1
2
4
5
6
7
9
8
10
3
b
ac
d
e
f
g
dp
cc
SEG A
SEG A
SEG A
SEG A
SEG B
SEG B
SEG B
SEG B
SEG C
SEG C
SEG C
SEG C
SEG D
SEG D
SEG D
SEG D
SEG E
SEG E
SEG E
SEG E
SEG F
SEG F
SEG F
SEG F
SEG G
SEG G
SEG G
SEG G
SEG DP
SEG DP
SEG DP
COM0
COM1
COM2
COM3
SEG DP
Figure 13-2: 4-digit 7-segment display schematic
Figure 13-1: Turn on switches
1 through 4 on SW8 to enable
4-digit 7-seg display
Enabling the display
4 digit
7-seg display
page 23
displays
EasyAVR
v7