I am looking for a way to use an external Low noise 10MHZ oscillator on the external Ref input on the AD-FMCOMMS3-EBZ evaluation board driven by an Avnet Zed board. I already removed the oscillator crystal and put the ceramic cap in and it works fine when I put an external 40MHZ source in. Now how do I reprogram the reference dividers to make it work with 10MHZ ? I looked through the PDF documentation for the registers to change and and canned software files on the zed board but couldn't figure out what file to change. Is this possible at that level or I have to develop my own driver to control the AD9361? I was hoping I could change a variable for the reference dividers but the supplied software doesn't seem to allow that.