X-NUCLEO-SAFEA1 Expansion Boards STMicroelectronics X-NUCLEO-SAFEA1 Expansion Boards are based on the STSAFE-A110 secure element that can be used with any STM32 Nucleo development board. This on-board STSAFE-A110 is customized with a standard profile for evaluation and is compatible with the Arduino UNO R3 connector. The STSAFE-A110 offers authentication and brand protection secure solutions. The X-NUCLEO-SAFEA1 expansion board works with free X-CUBE-SAFEA1 or XCUBE-SBSFU software packages containing sample code to demonstrate how to implement security applications.