adrv9002 fast boot with stored calibration coefficients

Hi inc,

Can you clarify your issue? From my reading of your question, it sounds like you're changing where the coefficients are stored, and nothing about the coefficients themselves.

To answer "can I use the same coeffs on every boot? Is it safe to use? I am trying to reduce the first boot time.":

Warmboot is intended to replace the need for intial calibrations - this is very effective for speeding up boot time, but best practice is to ensure that you only use the coefficients generated on the specific device that you're booting. If, for example, you save the calibration coefficients for one ADRV9002, and used those same coefficients to warm boot 10 different ADRV9002 chips, that might not work as well.

The calibrations have a much better chance of working well if the environmental conditions are the same at the time of the warm boot as they were at the original calibrations, when they were first saved. Furthermore, these calibrations are typically supplemented using tracking calibrations, so a small mismatch in environmental conditions may be compensated for, if you are using tracking calibrations. If, for example, you generated the Warmboot coefficients at 20 degrees C, but in the field, the ADRV9002 is operating at 80 degrees C, those coefficients may not work as well (or at all).

I hope that answers your queries, but let me know if you have any other questions.

Kind Regards,
Michał

Hi Michal,

Thanks and sorry for confusion.

We are planning to calibrate each unit independently. But the actual question was can the coefficients I get during the fist boot, be used all the time? Or does the ADRV9002 needs to be calibrated at least once on its first boot? (say we have two profiles for our application)

What we are currently doing is, we have two profiles and we calibrate the ADRV9002 on these two profiles on each first boot. Then we store the coefficients(separately) in the RAM memory. So, for further profile changes we use Warmboot feature to reduce the profile change time. And. further profile changes can happen any time during runtime.

From that point, we think that, if we calibrate the device on these two profiles and store the coefficients in a flash memory, we can also reduce the first boot time as well. From your answer, I understand that this is possible. But the limitation is the temperature. Unfortunately, there is no guarantee that the operating conditions will remain constant.

And, above temperature limitation brings new question. Lets say we have only one profile we consistently calibrate the ADRV9002 on each boot. Basically, it is a normal operation and doesn't involve Warmboot. And say the temperature is 20 C during calibration(first boot). Then device starts to operate and the temperature slowly increases to 80 C. Can the tracking calibrations sill compensate this much temperature change? Or, do we need to do re-calibrate the unit under this temperature?

Thanks.

Hi inc,

I'm still not sure that I understand your wording. Your two options sound like they are describing the same thing:
"Can the coefficients I get during the fist boot, be used all the time?"
"Or does the ADRV9002 needs to be calibrated at least once on its first boot?"

You can't get calibration coefficients without first calibrating. The coefficients that you get during the first boot are the results of the ADRV9002 being calibrated. If you don't calibrate the ADRV9002, you don't get coefficients. If I'm not understanding your question correctly, I'm afraid I might need you to try clarifying this again.

As for the tracking calibrations, I don't have the equipment to test this myself, but my understanding is that this is the purpose of these calibrations. The temperature of the ADRV9002 silicon die fluctuates even in static environmental conditions (e.g. when using TDD with long frames), so it's expected that tracking calibrations will keep up with it.

Kind Regards,
Michał

Hi Michal,

Thanks. I actually haven't received the notification email via the forum. So, I wasn't aware the your reply. Sorry for the late response.

Since the tracking calibrations take care of the on the fly tuning, we rely on this feature. We now store the calibration coeffs in a non volatile memory and start with warm boot with stored coeffs. So this ultimately reduced the boot time with almost no-cost!