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HMC778LP6CE handshaking sequence?

Question asked by Alejandro_FE on Apr 21, 2015
Latest reply on Apr 21, 2015 by MRichardson

Hello. I am working with a HMC778LP6CE eval kit and I am trying to program it through SPI iface using my own hardware. I have followed the instructions on the datasheet, my timming is correct (I am using a 1 MHz SPI CLK, CMOS levels).

 

I have tried setting an integer mode following the instructions on the datasheet (as no double-buffering is needed, writing 953Eh on Reg 06 and some value on Reg 03 should do the work) but there is just no way it works, the PLL just keeps unlocked. Surprisingly, if I use the provided (eval. kit) USB board with the provided software and I load an integer example file, then connect the SPI interface to my hardware and change the values of the registers with my own software, it works fine, but it won't work if I don't connect the SPI interface to the eval. kit USB board and load an example file first.

 

I have also tried replicating the R/W Register History of the eval. kit software with my hardware, but it still doesn't work.

 

I would like to know if there is some kind of handshaking routine that the provided software does and it triggers the PLL so it would get locked to the specified frequency, or something else I have been not considering

 

Thanks in advance.

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