EP80579 Datasheet, PDF (921/1916 Pages) Intel Corporation – Intel® EP80579 Integrated Processor Product Line

Intel^® EP80579 Integrated Processor
24.4.2.4
Read Byte/Word
Reading data is slightly more complicated than writing data. First a command to the
slave device must be written. Then it must follow that command with a repeated start
condition to denote a read from that device's address. The slave then returns one or
two bytes of data.
When programmed for the read byte/word command, the transmit slave address and
device command registers are sent. Data is received into the DATA0 on the read byte,
and the DAT0 and DATA1 registers on the read word. The order sent and received with
PEC disabled is shown in Table 24-36.
Read byte/word command with I2C_EN set produces undefined results. Software must
force the I2C_EN bit to 0 when running this command.
Table 24-36. Read Byte/Word Protocol without PEC
Read Byte Protocol
Read Word Protocol
Bit
Description
1
Start
2 – 8 Slave Address - 7 bits
9
Write
10 Acknowledge from slave
11 – 18 Command code - 8 bits
19 Acknowledge from slave
20 Repeated Start
21 – 27 Slave Address - 7 bits
28 Read
29 Acknowledge from slave
30 – 37 Data from slave - 8 bits
38 NOT acknowledge
39 Stop
Bit
Description
1
Start
2 – 8 Slave Address - 7 bits
9
Write
10 Acknowledge from slave
11 – 18 Command code - 8 bits
19 Acknowledge from slave
20 Repeated Start
21 – 27 Slave Address - 7 bits
28 Read
29 Acknowledge from slave
30 – 37 Data Byte Low from slave - 8 bits
38 Acknowledge
39 – 46 Data Byte High from slave - 8 bits
47 NOT acknowledge
48 Stop
The order sent and received with PEC enabled is shown in Table 24-37.
Table 24-37. Read Byte/Word Protocol with PEC
Read Byte Protocol
Read Word Protocol
Bit
Description
1
Start
2 – 8 Slave Address - 7 bits
9
Write
10 Acknowledge from slave
11 – 18 Command code - 8 bits
19 Acknowledge from slave
20 Repeated Start
21 – 27 Slave Address - 7 bits
Bit
Description
1
Start
2 – 8 Slave Address - 7 bits
9
Write
10 Acknowledge from slave
11 – 18 Command code - 8 bits
19 Acknowledge from slave
20 Repeated Start
21 – 27 Slave Address - 7 bits
August 2009
Order Number: 320066-003US
Intel^® EP80579 Integrated Processor Product Line Datasheet
921