EEPROM
is short for
Electrically Erasable
Programmable Read Only Memory
. It is
usually a secondary storage memory in devices
containing data that is retained even if the device
looses power supply. Because of the ability to
alter single bytes of data, EEPROM devices are
used to store personal preference and configuration
data in a wide spectrum of consumer, automotive,
telecommunication, medical, industrial, and PC
applications.
EasyAVR
™
v7 supports serial EEPROM which uses
I
2
C
communication interface
and has
1024 bytes
of available
memory. Board contains socket for serial EEPROMs in DIP8
packaging, so you can easily exchange it with different memory size
EEPROM IC. EEPROM itself supports single byte or 16-byte (page) write and
read operations. Data rate is 400 kHz for both 3.3V and 5V power supply.
In order to connect I
2
C EEPROM to the
microcontroller you must enable
SW5.7
and
SW5.8
as well as appropriate
SW6
switches
depending on socket you want to use, as shown
on
Figure 17-1
.
1kΩ
pull-up resistors necessary
for I
2
C communication are already provided on
SDA
and
SCL
lines once switches are turned
on. Prior to using EEPROM in your application,
make sure to disconnect other peripherals, LEDs
and additional pull-up or pull-down resistors from
the interface lines in order not to interfere with
signal/data integrity.
I
2
C is a multi-master serial single-ended bus that is used to attach low-speed peripherals to computer or embedded
systems. I²C uses only two open-drain lines,
Serial Data Line (SDA)
and
Serial Clock (SCL)
, pulled up with
resistors.
SCL
line is driven by a master, while
SDA
is used as bidirectional line either by master or slave device.
Up to 112 slave devices can be connected to the same bus. Each slave must have a unique address.
I
2
C EEPROM
1
2
3
4
5
6
7
8
O
N
SW5
EEPROM-SCL
EEPROM-SDA
SCL
SDA
DATA BUS
C25
100nF
VCC-BRD
VCC-BRD
VCC-BRD
R48
1K
R49
1K
A0
A1
A2
VSS
SDA
SCL
WP
VCC
1
2
3
4
5
6
7
8
U4
24C08
1
2
3
4
5
6
7
8
O
N
SW6
PB0
PB2
PC1
PC0
PC4
PC5
PA6
PA4
SCL4
SDA4
SCL3
SDA3
SCL2
SDA2
SCL1
SDA1
DIP20B
DIP40B
DIP28
DIP14
I2
C
SE
LE
CT
IO
N
Enabling I
2
C EEPROM
What is I
2
C?
page 27
Figure 17-1:
Schematic of
I
2
C EEPROM
module
connected to
DIP40B socket
pins
modules
Easy
AVR
v7
