What’s the specified tolerance on the Au v2 oscillator? I am intending to provide a RTC service in the card i’m developing. I only need accuracy to 1/100 second (10 milliseconds). I will be providing time references regularly from an external disciplined clock, but how often I need to provide the time references depends on how fast the oscillator drifts. If the drift is too big I will have to figure out a whole local clock disciplining scheme, which will be annoying.
According to the oscillator’s datasheet here, the stability and tolerance are both ± 30 ppm
Oops, this is the 12 MHz for the FT2232 XD
The 100 MHz one for the FPGA is this one and the tolerence is ± 25 ppm
The drift is ± 5 ppm the first year
Nice, if it’s in that regime, I can send a realtime reference every minute or so, and never drift enough to visibly glitch on the resolution that this thing delivers.
I mean, it’s a real time clock feature for an Apple II, the accuracy expectations are pretty lenient.
This is the actual datasheet for the one on the latest batch of boards. It’s still 25ppm with 3ppm shift for the first year.
AlchitryOsc.pdf (360.4 KB)
The actual oscillator we put on each batch may change with availability and cost but they’ll be comparable.