-- re-posting with smaller attachment --
On Thu, Mar 17, 2016 at 12:40 PM, Logan Cummings <logan.cummi...@gmail.com> wrote: > I was planning on using the Due's ADC to measure the voltage on the > integrator capacitor, but hadn't decided yet about a "good" current source > vs. a series resistor on the output of an XOR or DFF phase comparator to > put charge on the capacitor. > > Hopefully someone else can chime in with some better links and circuit > descriptions. > You might want to consider the approach used in the attached schematic and write-up. This is for an Arduino Micro based system, but you should be able to adapt it to work with the Due. The simple RC network works OK if you can set the ADC full scale range to 2.5 V or less, but shows some nonlinearity at the high end due to the exponential charging. I have been experimenting with a circuit that uses a better current source, which I can pass along if you are interested. So far the performance seems to be about the same as this simple circuit. -- --Jim Harman -- --Jim Harman
Arduino GPSDO Schematic v4.pdf
Description: Adobe PDF document
Arduino GPSDO notes.docx
Description: MS-Word 2007 document
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