Hardware sleep event enable register
| ENA_EVENT0 | Writing a 1 enables the Cortex-M4 core to put the part into any of the Power-down modes Deep-sleep, Power-down, or Deep power-down depending on the value in the PD0_SLEEP0_MODE register. |
| ENA_EVENT1 | Writing a 1 enables the Cortex-M0 core and the Cortex-M0 subsystem core to put the part into any of the Power-down modes Deep-sleep, Power-down, or Deep power-down depending on the value in the PD0_SLEEP0_MODE register. |
| RESERVED | Reserved, user software should not write ones to reserved bits. The value read from a reserved bit is not defined. |