Claus

Hallo CW2, sorry, I didn't mean "adjusting the internal clock", I meant "adjusting the accuracy of the internal clock". Is it possible? Thank you, Claus

Hallo Mario, Thank you for your answer as well. I thought of adjusting the internal clock (DateTime.Now) via software. But I fear it isn't possible (or is it?). If only the onboard crystal is accountable for the inaccuracy (is it?) I thougth of applying an external high precision oscillator to the XIN pin of the AT91SAM7X512 (instead of the crystal) by making a little mainboard modification . But the manual is telling something about another timing register setup when an external oscillator is driving the main clock... Has someone experience with this issue? Another approach would be to apply a much more accurate crystal. But this would only make sense, if the internal clock is exactly driven by the Crystal, that means, that a 100% accurate crystal would result in an 100% accurate internal clock. Does anybody know if this is true? Thanks, Claus

Hallo Stefan, Thanks for your comment. I use already a DS1307 RTC to set initially the Netduino internal clock. With the inaccuracy of the internal clock I have to do this at least every hour. To set the internal clock from the RTC you have to poll the RTC until a change of the second takes place and then update the internal clock. I want to avoid this often polling, because it may affect the interrupt driven data logging more than necessary. The best solution would be to get the internal clock more accurate. Any idea... ? Thanks in advance Claus

I found the assembly and my SD card is working now. However, thank you, Claus