BQ40Z50: PRES Pin Asserted

Fabio Gou

Expert 4375 points

Part Number: BQ40Z50

How can I understand “the average of four measurements” of PRES Pin asserted？

I guess it must be four consecutive samples "high"？ is it right?

over 1 year ago

0 Jose Couso over 1 year ago

TI__Mastermind 27321 points

Hi Fabio,

This is likely related to the 1 second report time. In normal mode, the devices takes measurements every 250ms, but it will report every 1 second. So, 4*250ms = 1sec.

It takes the average of the four samples in one second and it reports the average.

Regards,
Jose Couso

0 Fabio Gou over 1 year ago in reply to Jose Couso

TI__Expert 4375 points

But PRE is only 0 or 1. It is not like voltage or current.

How could this be averaged?

0 Jose Couso over 1 year ago in reply to Fabio Gou

TI__Mastermind 27321 points

Hi Fabio,

This is a better explanation. It looks like it does not take an average. If it is low for 4 samples (one second), the PRES flag is set.

Looking at the FW code, the best practice is to rely on the last sample within the second. The function is called four times in a second. The last time it is called, it will determine the true status of the PRES pin. The function primarily looks for the falling edge, if the pin is down, it will set PRES flag.

Regards,
Jose Couso

0 Fabio Gou over 1 year ago in reply to Jose Couso

TI__Expert 4375 points

Looking at the FW code, the best practice is to rely on the last sample within the second.

So if the first three samples are 1, only the last sample is 0. It will also change the PRES pin status?

i guess it must be continuous four samples.

0 Jose Couso over 1 year ago in reply to Fabio Gou

TI__Mastermind 27321 points

Hi Fabio,

The last sample should be 1, if not the PRES bit will clear.

Regards,
Jose Couso

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BQ40Z50: PRES Pin Asserted