LPC1768 RTC frequency check with WDT. Compare RTC against MCU's microsecond Timer.

Dependencies:   mbed

Check LPC1768 RTC crystal frequency using WDT. Measure with MCU's microsecond Timer. The MCU's crystal may be off a bit as well. I measured the RTC frequency error at 22 ppm. The spec for the RTC crystal is 20 ppm. Using NTP and a GPS, I had measured the MCU's crystal frequency error at -2 ppm.

Frequency measurements for other MCU/RTC cyrstals at


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