VL6524 datasheet(35/70 Pages) STMICROELECTRONICS

35 / 70 page

VL6524/VS6524

Host communication - I²C control interface

35/70

Start (S) and Stop (P) conditions

A START (S) condition defines the start of a V2W message. It consists of a high to low

transition on SDA while SCL is high.

A STOP (P) condition defines the end of a V2W message. It consists of a low to high

transition on SDA while SCL is high.

After STOP condition the bus is considered free for use by other devices. If a repeated

START (Sr) is used instead of a stop then the bus stays busy. A START (S) and a repeated

START (Sr) are considered to be functionally equivalent.

Figure 22.

START and STOP conditions

Acknowledge

After every byte transferred the receiver must output an acknowledge bit. To acknowledge

the data byte receiver pulls SDA during the 9th SCL clock cycle generated by the master. If

SDA is not pulled low then the transmitter stops the output of data and releases control of

the bus back to the master so that it can either generate a STOP or a repeated START

condition.

Figure 23.

Data acknowledge

START

condition

STOP

condition

SDA

SCL

START condition

Negative acknowledge (A)

Acknowledge (A)

Clock pulse for acknowledge

SDA data output

by transmitter

SDA data output

by receiver

SCL clock from

master

VL6524 Datenblatt(PDF) 35 Page - STMicroelectronics