Datasheet ESRF-ESF

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Software Reset Function [0xFE]

The device has an additional option to perform a software reset via the I2C communication

interface. This option is useful in specific cases depending on the application. For instance,

the user could issue a S/W reset to assure correct initialization after a hot-plug connection.

The procedure to reset the device is the same as changing a register, followed by the byte

0xFE. In other words, the user must first send the byte 0x8A (7 bit address plus write bit) and

acknowledge bit and immediately reset itself. After 100 milliseconds, the device will be ready

to give its first valid sample.

At power on reset, the sensor defaults to transmission of the contents of the Flow Data

Register. If the master device transmits the selected sensor 7-bit address (0x45) with R/W bit

set, the sensor returns the contents of the Flow Data Register after acknowledging (ACK) by

holding the SDA line low. The master should then provide at least 18 clock pulses on the SCL

line in order to readout the two Flow Data Bytes. An acknowledge bit (ACK) should be provided

pulse. The same frame structure also applies to a Temperature Data transaction. An example

of such a transaction can be seen below.

If in any case the master sends a slave address or a register address that is not recognized a

NACK condition will be returned by the sensor. The sensor supports clock stretching

functionality

Master

MCU

VDD

FLOW

SDA

SCL

S

...

Slave Add+W

A

Register Add

A S

Slave Add+R

A

Data 0

A

Data N

N P

Start

Stop

Slave ACK

Master ACK

SCL

SDA

Master NACK