Incorrect timing information with ADP3450

[leonvs]

The other day I had the following situation:

I was monitoring an 8MHz signal which was reported by the ADP3450 as 13.333MHz. This was both on the logic analyzer and on the scope. Since I was convinced the signal was 8MHz, I checked with a different logic analyzer which correctly reported the expected 8MHz. 

Continuing the next day (after a power cycle) the ADP3450 reported the correct 8MHz.

Is this behaviour observed by anyone else or does somebody have a clue what could be causing this behaviour?

[attila]

Hi @leonvs

Could it be a wrongly specified external/reference frequency ?

[leonvs]

Thanks for the reply, no, I never touched this dialog, always use the default internal clock. I remember to have it seen before, this was during a recording session of the logic analyzer. Payed no attention to it then. 

Will keep my eye open and pay more attention when it happens again. Could it have to do with PLL's not being locked?

[leonvs]

It happened again, was using two scope channels, triggering on SPI traffic. The SPI frequency is 2MHz and it was reported as 3MHz. The signals on the analog channels were off likewise. Looked at the device status and everything was reported fine.

Switched the device (ADP3450) off, waited for a few seconds and restarted it. After this, using the same DUT everything was fine. The DUT has not been reset and just remained running while the ADP3450 was reset.

Before this happened I have been configuring Ethernet access which I could not get working. Connecting to my router and using the routers DNS, an IP address was handed out to the ADP3450. The manual said to reboot and the device should make a clicking sound. This sound was not heard and only USB access was reported in the device manager. Don't know if this can have anything to do with the mentioned timing issue but feel like mentioning it does not hurt.

[attila]

Hi @leonvs

The system clock frequency could be wrong after software reboot.

It will be fixed for the next version.
Thank you again for the observation.