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I/O UPDATE timing for AD9957

Question asked by ysuzuki on Feb 3, 2015
Latest reply on Feb 13, 2015 by Georgy

Hello ,


I have a question about operation of I/O UPDATE for AD9957.

In the lower left of datasheet(rev.C) P.47, it's described follows.


  The I/O update can either be sent after each communication cycle or when

  all serial operations are complete.


It seems that I can configure AD9957 correctly by one I/O UPDATE pulse after all SPI operation.

But AD9957 does not work when I send I/O UPDATE after sending all register data.

(AD9957 works well when I send I/O UPDATE after each communication cycle.)

I am sending the data in sequence of reg00 to reg19 .


Do I need send the data according to a rule of sequence of register if I send "I/O UPDATE" after all communication cycle ?



Best regards,




edited this message, ysuzuki