Quantcast
Channel: EngineerZone: Message List
Viewing all articles
Browse latest Browse all 22625

Re: FMCOMMS1: Clock Genarator adjustments...

$
0
0

Hey Kyle...

On FMCOMMS1 we have 19.2MHz which generate 768MHz for Sys Clock. I did not changed this in the original clock generation drivers written by AD for 122.88MHz.

You are right about R and S... it is a little difference in the datasheet and the Excel file calculation... comparing the  original registers for 122.88MHz I should calculate digital loop filter coeffs (alpha, beta, ...) by 30MHz*S/R and for S and R I should use 30MHz*(S+1)/(R+1)... am I right? I checked with an oscilloscope, I measure 80MHz with this number...

For instance, I set as below:

     R: 125

     S: 335

     U: 0

     V: 1

     (The rest are calculated in the Excel file with R=126 and S=336)

     alpha0: 0xE438

     alpha1: 0x9

     alpha2: 0

     alpha3: 0

     beta0: 0x13141

     beta1: 0x10

     gamma0: 0x147d8

     gamma1: 0x10

     delta0: 0x44cb

     delta1: 0x0b

 

You may have another suggestion for R and S.

When I read AD9548_REG_DLL_STATUS_0 (0x0D0A) I have 0x62 shows Freq is lock bot Phase is not... I checked with original 122.88MHz I have the same result... Is is OK?


Viewing all articles
Browse latest Browse all 22625

Trending Articles



<script src="https://jsc.adskeeper.com/r/s/rssing.com.1596347.js" async> </script>