Hi, so I have managed to get my device functioning correctly now and generating the frequency I expect. However, it doesn't do this upon power-up of the device. The datasheet states that the registers must be written to in order from R5 through to R0, which is what I am doing. After this initialisation sequence has been followed the device outputs a random frequency, which is the same everytime, but unrelated to my INT, FRAC and MOD values. If I then re-write register 0 with the values that I wrote to the device during its initialisation sequence then i get the frequency that I am expecting. So far i have got round this by putting a 100us delay in between writing R1 and R0 during the initialisation sequence, but i am curious as to why this cures the problem. Just to note...I am conforming to all of the setup times specified in the datasheet.