A processing system comprising a first sub-circuit configured to be powered by a first supply voltage and a second sub-circuit configured to be powered by a second supply voltage. The first sub-circuit comprises a general-purpose input/output register. The second sub-circuit comprises: a storage circuit configured to selectively store configuration data from the general-purpose input/output register; an input/output interface, at least one peripheral and a selection circuits to exchange signals of the peripherals, and the stored configuration data with the input/output interface. A power management circuit is configured to manage a normal operating mode, and a low-power mode during which the configuration data are maintained stored and the first sub-circuit is switched off. The power management circuit activates the low-power mode in response to receiving a commands, and resumes the normal operating mode in response to a wake-up events.