[time-nuts] Rb Oscillator - rather fundamental question
time-nuts at kasperkp.dk
Wed Feb 24 07:14:48 UTC 2010
On 02/23/2010 11:10 PM, Matthew Smith wrote:
> BTW: does anyone know if a 0.55V p-t-p sine wave from an Rb source would
> be enough to clock an Atmel AVR microcontroller? The crystal/clock
> input *is* an amplifier, but didn't know if I'd need to do anything to
> the signal first, to get it closer to the 5V logic level.
Set the fuses as you would have for a 10MHz crystal, and capacitively
couple the source to XTAL1. Leave XTAL2 open.
Do not set the fuses for 'external clock mode'.
Do put something like 100pF+1k Ohm in series with the input. While they
won't promise anything, I have deliberately run 1A into the protection
diodes of an ATMega16 for many seconds and still had a functional part.
More information about the time-nuts