36.5.16.1 Introduction

The I/O line configuration freeze function can reinforce the protection against the effects of an abnormal access resulting from a Single-event upset that may corrupt the value of one bit on the system bus during an access to the PIO or any other peripheral. Freezing the configuration of an I/O line prevents an unexpected access from modifying the configuration of the I/O line. Once the freeze is done, the I/O line configuration cannot be modified whatever software sequence is performed on the PIO.