Teseo-LIV4F wakeup, interrupt, and nReset confusion

[nikos_vallianos]

It is unclear to me how to place the Teseo-LIV4F to a low power state. I am a bit confused with the nReset and the Wakeup or Extint pins. In the datasheet, pin 5 is marked as an input and named "WakeUp" and pin 9 is marked as an input and named nReset. Pin 18 is also an input and is named PRG but its description says "Program or WakeUp from DeepStandby. What is DeepStandby?

The Teseo-LIV4F has a $PSTMFORCESTANDBY command and the datasheet lists a SW-STANDBY consumption of 10uA with VCC=VBAT=3.3V (which is great for me) but the Hardware Manual says "Teseo-LIV4F offers 1 way of standby: HW standby".

What is the best way to enter and exit standby with VBAT at 3.0V and VCC also at 3.0V? Or is it better to just control VCC?

 

[Francesco Virlinzi]

Hi

You can use the commands:

 - $PSTMFORCESTANDBY,<seconds> to sleep N seconds and in case you can asinctronously wakeup the module using the pin Wakeup

 - $PSTMFORCESTANDBY,<seconds>,1 to deep-sleep N seconds and in case you can asinctronously wakeup the module using the pin PRG

 

[nikos_vallianos]

Thank you. I am sure all engineers are able to make some guesses. It would be useful to get an answer from an ST engineer or someone that has used the chip and knows the answers to these questions, that should have been part of the documentation:

1. Are the Wakeup and the PRG pins active low? Is the recommended low time same as tRSTL (100ms)?

2. Should the Wakeup and PRG pins be left HIGH or floating the rest of the time?

3. What is the difference between Sleep and Deep Sleep? Does the RTC run in both of them if the VBAT is powered?

Thank you!

[Francesco Virlinzi]

Hi

- RESETn is active low; you can keep it high or floating when not used; (it's better the host can drive this pin to guarantee firmware update procedure on the field)

- PRTRG is archive low; you can keep it high or floating when not used;

- Wakeup is active high; you can keep it low or floating when not used;

 

In deep-sleep the system moves in standby more parts to guarantee the lowest power consumption possible.