Power Consumption by GPIO.

[A3]

I am using STM32F779NI for my project.

https://www.st.com/resource/en/application_note/dm00315319-stm32-gpio-configuration-for-hardware-settings-and-lowpower-consumption-stmicroelectronics.pdf

Section 6.1 of above pdf states that unused input GPIO should be configured as analog mode to reduce power consumption by Schmitt Trigger.

Now since after power on reset most of the GPIOs are in input floating mode by default, does that mean all those unused GPIOs needs to configure in analog mode to reduce the consumption?

[Peter BENSCH · Accepted solution]

Input floating means digital input without pull-up or pull-down, but connected to the internal Schmitt Trigger. When unused such a pin might catch some noise from the external world , i.e. triggering the Schmitt Trigger, which causes unwanted current consumption.

Therefore unused GPIOs should be configured in analog mode, if the total current consumption of the STM32 is of importance.

BTW: devices prior STM32L476 were configured by default to (digital) input floating, newer derivatives are mostly already set to analog input. To avoid confusion, it is still recommended to explicitly configure unused GPIOs for analog mode.

/Peter

[A3]

Thanks