14.2 Clock Sources
The device has the following clock source options, selectable by Flash Fuse bits as shown below. The clock from the selected source is input to the AVR clock generator, and routed to the appropriate modules.
Device Clocking Option | CKSEL[3:0] |
---|---|
Low Power Crystal Oscillator | 1111 - 1000 |
Low Frequency Crystal Oscillator | 0101 - 0100 |
Internal 128kHz RC Oscillator | 0011 |
Calibrated Internal RC Oscillator | 0010 |
External Clock | 0000 |
Reserved | 0001 |
Note: For all fuses, '1' means unprogrammed while '0' means programmed.