Ability to wake up from analog signal rising above a threshold level?

[dlofting9]

Posted on March 08, 2016 at 10:48

Hi, we are considering using an STM32F7 microcontroller however we need to establish whether or not a microcontroller from this range would be able to wake up from a low power mode from an analog signal rising above a configurable threshold level.

I understand that a rising or falling edge on a WKUP pin can trigger an IRQ which wakes the device up, however I need to clarify if this can be extended to wake up the device only when the input signal rises above 2V for example (and for that threshold to then be reconfigured to lets say 2.2V dynamically).

This seems like a great range but we need to ensure that it can meet specifications before we can use it. Hopefully someone can shed some light on this.

[re.wolff9]

Posted on March 08, 2016 at 12:39

I would suggest that you check out the datasheet and reference manual for the chip you intend to use. 

Check that it has an analog comparator, and/or analog watchdog. Read the referencemanual on the modules that you find it has. 

If you find your device has a comparator, but not the 'analog watchdog' then you may need to use the DAC for setting the threshold, and then using external routing to route that to a pin of the comparator. Then important things become: can the comparator wake up the chip? and Does the DAC keep working in sleep?

[Walid FTITI_O]

Posted on March 10, 2016 at 10:46

Hi DL3141, 

The comparator wakeup capability that you are asking for is available in the following STM32 familes: STM32F3x , STM32F0x, STM32L0x, STM32L4x.

-Hannibal-

[dlofting9]

Posted on March 24, 2016 at 18:04

Thanks.