Datasheet

ADM1066
Rev. E | Page 29 of 32
56
P
The master sends a command code telling the slave device
to erase the page. The ADM1066 command code for a page
erasure is 0xFE (1111 1110). Note that for a page erasure to
take place, the page address must be given in the previous
write word transaction (see the Write Byte/Word section). In
addition, Bit 2 in the UPDCFG register (Address 0x90)
must be set to 1.
04609-040
2413
SLAVE
ADDRESS
COMMAND
BYTE
(0xFE)
SWA A
Figure 40. EEPROM Page Erasure
As soon as the ADM1066 receives the command byte,
page erasure begins. The master device can send a stop
command as soon as it sends the command byte. Page
erasure takes approximately 20 ms. If the ADM1066 is
accessed before erasure is complete, it responds with a
no acknowledge (NACK).
Write Byte/Word
In a write byte/word operation, the master device sends a
command byte and one or two data bytes to the slave device, as
follows:
1.
The master device asserts a start condition on SDA.
2.
The master sends the 7-bit slave address followed by the
write bit (low).
3.
The addressed slave device asserts an ACK on SDA.
4.
The master sends a command code.
5.
The slave asserts an ACK on SDA.
6.
The master sends a data byte.
7.
The slave asserts an ACK on SDA.
8.
The master sends a data byte or asserts a stop condition.
9.
The slave asserts an ACK on SDA.
10.
The master asserts a stop condition on SDA to end the
transaction.
In the ADM1066, the write byte/word protocol is used for three
purposes:
• To write a single byte of data to the RAM. In this case, the
command byte is RAM Address 0x00 to RAM Address 0xDF,
and the only data byte is the actual data, as shown in Figure 41.
04609-041
SLAVE
ADDRESS
RAM
ADDRESS
(0x00 TO 0xDF)
S W A DATAAPA
2413 576 8
Figure 41. Single Byte Write to the RAM
• To set up a 2-byte EEPROM address for a subsequent read,
write, block read, block write, or page erase. In this case, the
command byte is the high byte of EEPROM Address 0xF8
to EEPROM Address 0xFB. The only data byte is the low
byte of the EEPROM address, as shown in Figure 42.
04609-042
SLAVE
ADDRESS
EEPROM
ADDRESS
HIGH BYTE
(0xF8 TO 0xFB)
SWA
EEPROM
ADDRESS
LOW BYTE
(0x00 TO 0xFF)
APA
2413 5 76 8
Figure 42. Setting an EEPROM Address
Because a page consists of 32 bytes, only the three MSBs of
the address low byte are important for page erasure. The
lower five bits of the EEPROM address low byte specify the
addresses within a page and are ignored during an erase
operation.
• To write a single byte of data to the EEPROM. In this case,
the command byte is the high byte of EEPROM Address 0xF8
to EEPROM Address 0xFB. The first data byte is the low
byte of the EEPROM address, and the second data byte is
the actual data, as shown in Figure 43.
04609-043
SLAVE
ADDRESS
EEPROM
ADDRESS
HIGH BYTE
(0xF8 TO 0xFB)
SWA
EEPROM
ADDRESS
LOW BYTE
(0x00 TO 0xFF)
APA
2413 5 7
A
9
DATA
86 10
Figure 43. Single Byte Write to the EEPROM
Block Write
In a block write operation, the master device writes a block of
data to a slave device. The start address for a block write must
have been set previously. In the ADM1066, a send byte opera-
tion sets a RAM address, and a write byte/word operation sets
an EEPROM address, as follows:
1.
The master device asserts a start condition on SDA.
2.
The master sends the 7-bit slave address followed by
the write bit (low).
3.
The addressed slave device asserts an ACK on SDA.
4.
The master sends a command code that tells the slave
device to expect a block write. The ADM1066 command
code for a block write is 0xFC (1111 1100).
5.
The slave asserts an ACK on SDA.
6.
The master sends a data byte that tells the slave device how
many data bytes are being sent. The SMBus specification
allows a maximum of 32 data bytes in a block write.
7.
The slave asserts an ACK on SDA.
8.
The master sends N data bytes.
9.
The slave asserts an ACK on SDA after each data byte.
10.
The master asserts a stop condition on SDA to end the
transaction.
04609-044
SLAVE
ADDRESS
SWA
2
COMMAND 0xFC
(BLOCK WRITE)
413
A
5
BYTE
COUNT
6
A
7
A
910
A PA
DATA
1
8
DATA
N
DATA
2
Figure 44. Block Write to the EEPROM or RAM