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3.11 Generic I2C Read Command and Response

3.12 Board Test Command and Response

3.13 Other Commands for Different Applications

Generic I2C Read Command and Response

USB PACKET

USB

COMMAND

BYTE 0

USB PACKET

PACKET

COMMENTS

DESCRIPTION

COMMAND

BYTES 6–63

BYTE 1

BYTE 2

BYTE 3

BYTE 4

BYTE 5

CODE

Y = 1st

X # of

The 1st byte

byte to

bytes (1

of data to

write +

to 62) to

write is usually

Generic I2C

0x1D

A number of bytes (2 to 60) to write

read bit 1

read back

(device

Read

USB

address < 1 +

byte 62

byte 63

write bit of 0).

USB PACKET

USB

COMMAND

BYTE 0

USB PACKET

PACKET

COMMENTS

DESCRIPTION

COMMAND

BYTES 6-63

BYTE 1

BYTE 2

BYTE 3

BYTE 4

BYTE 5

CODE

Response from

Success: 0

0x9D

X number of bytes (1 to 62) read back from slave

Generic I2C

Fail: 1

Read

This is a generic I2C Read transaction command that can be applied to majority of I2C applications. The

detailed bit-banking is as follows: I2C start

→ repeat (write 1 data byte, slave ACK) for A number of

times

→ repeated start → write Y → slave ACK → read X number of bytes (with master ACKs in

between) from a slave

→ master NACK → I2C stop.

Basically, all the transaction bytes are placed one after another, such as address byte (7-bit slave address

shifted left by 1 bit + write bit of 0), one or multiple command bytes, then repeated start, write address

byte Y (7-bit slave address shifted left by 1 bit + read bit of 1), and read back x number of bytes from the

slave device being addressed. The USB interface adapter carries out the bit banking. For maximum

flexibility, this generic command for any I2C read transactions is recommended.

USB

PACKET

USB

COMMAND

BYTE 0

PACKET

COMMENTS

DESCRIPTION

COMMAND

BYTE 1

BYTE 2

BYTE 3

BYTE 4

BYTE 5

BYTES 6-63

CODE

Start toggling eight

LEDs connected to the

Board Test

0x7F

eight GPIO pins

simultaneously for 5 s.

USB

PACKET

USB

COMMAND

BYTE 0

PACKET

COMMENTS

DESCRIPTION

COMMAND

BYTE 1

BYTE 2

BYTE 3

BYTE 4

BYTE 5

BYTES 6-63

CODE

Response from

0xFF

Board test is done

Board Test

This command is for internal testing of USB interface adapter evaluation boards during production only.

Do not use this command for any other application.

For applications other than I2C/GPIO, such as PMBUS, SMBUS, HDQ, etc., see the corresponding

literature for more details.

Firmware Programming and Communications Protocol

SLLU093 – August 2006

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