LE2432RDXA
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9
4) Acknowledge Bit (ACK)
The Acknowledge Bit is used to indicate a successful byte data transfer. The receiver sends a zero to
acknowledge that it has received each word (Device Code, Slave Address etc) from the transmitter.
5) Device addressing
To transmit between the bus master and slave device (EEPROM), the master must send a Start condition
to the EEPROM. The device address word of the EEPROM consists of 4-bit Device Code, 3-bit Slave
Device address code and 1-bit read/write code. By sending these, it becomes possible to communicate
between the bus master and the EEPROM.
The upper 4-bit of the device address word are called the Device Code, the Device Code of the EEPROM
uses 1010b fixed code. This device has the 3-bit of the Slave Device address as the Slave address (S0,
S1, S2). The value of Slave address are fixed S0 = 0, S1 = 0, and S2 = 1.
When the Device Code is received on the SDA, the device only responds if Slave address pin tied to VDD
or VSS is the same as the Slave address signal input. The 8
th
bit is the read/write bit. The bit is set to 1 for
Read operation and 0 for Write operation. If a match occurs on the Device Code, the corresponding
device gives an acknowledgement on SDA during the 9
th
bit time. If device does not match the Device
Code, it deselects itself from the bus, and goes into the Standby mode. Use the Random Read command
when you execute reading after the slave device was switched.
1 0 1 0 S2 S1 S0 R/W
S2 = 1, S1 = 0, S0 = 0
Device Code
Slave
Address
MSB
LSB
Device address word
Acknowledge
Bit output
Start
condition
1
SCL
From Transmitter
SDA
(From Transmitter)
SDA
(EEPROM output)
8
9
t
AA
t
DH
