OPT3101-SDK: Negative calibration coefficients end up equal to 0

Hello Lucas,

Will you share your inputs for coffI, coffQ, coffIReg, coffQReg, and commonScale?  Also what you are getting as an output?

Rahland

Hi Rahland, 

In my application, I only use TX0. My inputs are the following:

Illumination-temperature xtalk:

- I (HDR0) = -10.816 (Reg=0) ; Q (HDR0) = 8.912 (Reg=46)

- I (HDR1) = -10.052 (Reg=0) : Q (HDR1) = 65.033 (Reg=218)

- commonScale = 7

Phase-Ambient xtalk:

- coeff0 = -0.317 (Reg=0) ; coeff1 = -0.052 (Reg=0) ; coeff2 = 0.147 (Reg=75); coeff3 = 0.045 (Reg=22)

- commonScale = 4

The Reg values and the outputs are always the same from what I can read in the registers afterwards. 

Lucas

Hello Lucas,

Thank you for your feedback.  Due to the holidays, i will get back you in a couple weeks.

Rahland

Hello Rahland,

Do you have any update on this matter ? 

Lucas 

Hello, 

Do you have any news on this issue ? 

Lucas

Hello Lucas,

What hardware are you using now?

Rahland

Hello Rahland, 

I'm using a custom board made following the provided guidelines, and a STM32 microcontroller.

Lucas

Lucas,

Which version of the SDK are you using?

Rahland

Rahland, 

As stated earlier, I'm using SDK v0.9.1.

Lucas

Hi Lucas,

Jumping in here since Rahland is out of office this week so apologies if I am missing anything you guys has discussed already. I understand that the negative temp coeff seems to be counted as 0 by the SDK. How do you know that it is counted as 0? Are you able to print out the Icoeff, Qcoeff and IcoeffReg and QcoeffReg values and send over so we can pinpoint when it is getting set to 0? Can you share the coeff register values written to the device as well? 

Best,

Alex

Hi Alex, 

We know that the coefficients are counted as 0 by reading in the corresponding registers after initialization. When trying to find the source of our measurement problems, it appeared to us that these registers were staying at 0. From what we can tell, it seems that the coefficients are set to 0 when they are casted into uint8_t or uint16_t (see file OP3101DesignCoefficients.cpp line 265, file OPT3101Calibration.cpp line 51-57 and 93) and thereafter written in the registers as 0. 

I attached a screenshot describing the input and the outputs of the system regarding these calibration coefficients. You can observe that the reg values corresponding to negative values are set to 0.

Could we consider the registers as signed registers and instead cast those variables into int8_t or int16_t, or is this "solution" not supported by the OPT?

Best, 

Lucas

Hello Lucas,

As per your first request, we were focusing in on negative coefficients with the illumination xtalk and were unable to replicate results.  We are now focusing in on phase offset temp xtalk.  We will get back to you on results.

Rahland