12.4.5 BFRC Oscillator

The dsPIC33A devices contain one instance of the Internal Backup Fast RC (BFRC) Oscillator and can function as the system clock in the event of an FRC failure. The BFRC Oscillator provides a nominal 8 MHz clock without requiring an external crystal or ceramic resonator, which results in system cost savings for applications that do not require a precise clock reference. The BFRC oscillator can be enabled or disabled by the BFRCEN bit in the OSCCTRL register and is ready when the BFRCRDY bit is set in the OSCCTRL registers. The BFRC is always enabled after any Reset.

The application software can tune the frequency of the oscillator using the TUN[5:0] bits in the FRC Oscillator Tuning register BFRCTUN.