We used the evaluation board EVAL-ADF4351 in our project. Instead of the USB, an external microcontroller was used to write to registers via SPI. However, we failed. Are the test points CLK, DATA and LE on the evaluation board used for external controlling? In other words, is the evaluation board only suit for USB conrolling?
Good to here. Let me know if you have any other questions.
I understand that this is an old directory but I have the same problem. I found this discussion and did take out the R51, R52, and R56, but it did not work still.
When I run SPI, the lock detects LED turned ON which is a good sign and it was not turn ON when these resistors were connected.
1st clk, 2nd data and 3rd is LE.
I hope I will get a reply from you. Thank you.
Thank you for your reply. As you said for 35Mhz and 1Ghz '' it looks like you are driving a square wave into the spectrum analyzer or over driving the input '' then the output signal generation from EVAL is wrong! As it supposes to sinusoidal output wave.
Does it means that there is something wrong with SPI communication? What should I do?
Why not look at the output with scope instead of a spectrum analyzer, you certainly can at 35MHz.
Hello, Here is the 35Mhz signal from the scope.
A certain amount of mismatch is observed, as for 35Mhz acquire frequency is 34.78Mhz and peak to peak voltage should be 1.125v but it is 1.48v.
'' I found a serious problem! Let me allow to say, As there are differential outputs from ADF4351 Eval board and these differential signals I need for my quadrature modulator as it is the differential modulator. Now after the SPI, the board should support to produce 2 same signals(frequency, power and out of phase with each other) but it did not. Let say for 35Mhz, channel 1 and 2 connected to the scope and found that channel1 signal is ok but channel 2 observation is wrong.'' am I sound right?
However, I have no clue how to solve it now.
My idea was wrong! I said wrong in the last reply. I put back resistors and see the observation from both channels and found the same for 35Mhz. The output 2 channels from eval board are differential but I don't actually know they are performing. In general differential amplifier as I know it gives 2 output range in the same freq. and amplitude but here clueless.
However, I checked other things on my set up and found some connections problem, solve it and found that it is working.
Great. I'm glad to hear you got things working. Let me know if you have other questions.