15.4.8 IO Settings Retention Mode

Before entering Backup mode with VDD3V3 voltage always supplied, the IO lines can be configured to keep their current states (input/output/pull-up/pull-down) when VDDCORE voltage is no longer supplied. This retention mode prevents any extra power consumption, current path or electrical compatibility with external devices connected to the IO lines.

When waking up from Backup mode (with no VDD3V3 voltage supplied), all IO lines are reset to their default state. Refer to “Reset State” in the table “Pin Description”.

IO retention can be configured in the IO Retention register. The granularity of the configuration is 8. Refer to the IO Retention register in the section “Special Function Registers (SFR)” for further details.