I have been using the HMC767 evaluation board for a few weeks controlling it from our own DSP. Then we noticed that the frequency was not what we expected and we decided to troubleshoot it using the Hittite evaluation software. We realized that the evaluation software showed a "Lost Communication" message. We used the same Hittite USB Interface to control a different HMC767 evaluation board and this time it was working OK, which means that the Software + USB Interface combo is working fine. We then started troubleshooting the messages sent by the USB interface to the Evaluation Board and noticed that there is a difference between the working HMC767 and the bad HMC767 (please see attached). Also, please note that we measured all voltages and currents and they are the same between the two boards.
Can anybody help me fix this issue? Or at least understand why this is happening?
This was answered via email.
The “lost communication” message means the software is not able to read the chip id (Reg 0x00). Usually this happens because the chip has gotten into the wrong SPI mode. In this case power cycle the eval board leaving the GUI connected. Clicking “check lock” should come up with “lost lock” -- this indicates comms are working. Now load a register config file to get the part locked.
This error also occurs if the USB isn't plugged in and I suspect might occur if the memory chip on the eval board were damaged.