Re: W8TEE B40 real time clock connections #w8tee

Rob Cox (N4MN)
 

Hi Don - 

I finally gave up on the RTC. I could live with slowing down the clock display updates but after some investigation, I found out that the RTC was messing with the AD9850. The output frequency of the 9850 at 7.000.000 Mhz is 39.2 Mhz and at 7.300.000 MHz it is 54.2 Mhz. Clearly nowhere close to 5Mhz or 4.7Mhz that I expected.
 
I wrote a small sketch using the AD9850SPI library and I could set the output frequency to 5Mhz just fine, so I know that the AD9850 was working properly. 
 
Mike (K5ESS) pointed me to a email discussion regarding the Antenna Analyzer that seemed to indicate that there may be a conflict between the AD9850 and other peripherals. In the email discussion on the AA boards, it was an SDCard interface, here it seems to be the RTC. Here is the link to the PDF
 
I found that the AD9850 runs properly until I enable the realtime clock. As soon as I hook-up the RTC module and uncomment the #define REALTIMECLOCK, then the output of the AD9850 goes wonky.
 
I hope to get some time over the holidays to dig into this a little deeper.

73,
-Rob (N4MN)
 
 

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