MSP430F47187: Hardware reset using battery and VCC both to microcontroller

Part Number:MSP430F47187

hi,

i am using MSP430F47187 and we use two supply for microcontroller.

1- VCC comes from capacitive supply.

2- battery CR2032 gives 3.1 volt.-----VBAT

now i want circuit which uses VBAT and VCC and switch to one supply to ON the microcontroller.

when VCC & VBAT is present  then it will switch to vcc and on the uc.

when battery VBAT is available and VCC is off then micro will ON through VBAT.

also please suggest reset circuitry.