Function of ALERT pin(#19) for STUSB4500

[WGao.1]

In STUSB4500 datasheet, it says below for ALERT pin:

Pin 19, B2, ALERT, OD, I2C interrupt, active low open drain, To I2C master, ext. pull-up.

What does it mean - is the signal triggered when I2C command is sent from I2C master to STUSB4500?

Thanks,

Winston

[Peter BENSCH]

ALERT is a signal from the STUSB4500 to the master and signals some transmission. You will also find it in the libraries, e.g. STSW-STUSB003. 

When your question is answered, please close this topic by choosing Select as Best.

Regards

/Peter

[WGao.1]

Hi Peter,

Thanks for the answer. I have read the STW-STUSB003 but it does not give a hint as to when the signal will be sent.

That is what I want to know: can you give me some examples as to what transmission is signaled? Will the signal be sent once for each I2C transaction?

Thanks,

Winston

[Benoit FORET]

Hi Winston,

ALERT pin is not triggered I2C events but functional events. In the STSW-STUSB003 package, you can find a DOC directory which contains the product register map. ALERT pin behaviour can be configured by masking/unmasking relevant events or interrupts according to your application requirements. See ALERT_STATUS registers and similar @ 0x0B, 0x0C etc...

Hope it helps,

Rgds,

Benoit

[FColl.1]

@Benoit FORET​  Why has the datasheet not been updated to include the functional description this pin?

[Benoit FORET]

Hi. Thanks for your suggestion.

So far, this is a choice we made to document software related features in a separate section.

Rgds