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How to change register settings in HMC704?

Thread Summary

The user inquired about handling register settings shorter than 24 bits in HMC SPI mode. The final answer confirmed that all register transfers require 24 data bits, and unused bits should be filled with 0 or 1 in the MSB positions. The product supports two SPI modes, and details are provided in the associated application note.
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I want to change more register settings than just N, N-fract, and charge pump values.  All of those registers are 24 bits long, whereas others are not (for example, Reg 06h is 23 bits long).  Given that the datasheet specifically says to place 24 data bits on the bus (in HMC SPI mode), should I fill with zeros, for words <24 bits?  And if so, should I fill the LSBs or MSBs?  It’s my understanding that I issue a 0 to indicate a Write cycle, then 6 address bits, then 24 data bits, then the bus goes away after the 32nd clock edge.  But it’s not clear how this would work for words shorter than 24 bits.