TSL2580, TSL2581

LIGHT-TO-DIGITAL CONVERTER

TAOS098 − MARCH 2010

9

The LUMENOLOGY

r Company

r

r

Copyright

E 2010, TAOS Inc.

www.taosinc.com

When an SMBus Block Write or Block Read is initiated (see description of COMMAND Register), the byte

following the COMMAND byte is ignored but is a requirement of the SMBus specification. This field contains

the byte count (i.e. the number of bytes to be transferred). The TSL2580 (SMBus) device ignores this field and

extracts this information by counting the actual number of bytes transferred before the Stop condition is

detected.

until a NACK is sent by the Master.

The data formats supported by the TSL2580 and TSL2581 devices are:

−

The transfer direction in this case is not changed.

−

At the moment of the first acknowledgment (provided by the slave receiver) the master transmitter

becomes a master receiver and the slave receiver becomes a slave transmitter.

−

During a change of direction within a transfer, the master repeats both a START condition and the slave

address but with the R/W bit reversed. In this case, the master receiver terminates the transfer by

generating a NACK on the last byte of the transfer and a STOP condition.

For

a

complete

description

of

SMBus

protocols,

please

review

the

SMBus

Specification

at

at http://www.semiconductors.philips.com.

Wr

7

Data Byte

Slave Address

S

1

AP

A

8

11

1

1

XX

A

Acknowledge (this bit position may be 0 for an ACK or 1 for a NACK)

P

Stop Condition

Rd

Read (bit value of 1)

S

Start Condition

Sr

Repeated Start Condition

Wr

Write (bit value of 0)

X

Shown under a field indicates that that field is required to have a value of X

...

Continuation of protocol

Master-to-Slave

Slave-to-Master