Need higher resolution speed measurement in FOC code.

In my sensorless application driving a BLDC I need the best resolution possible.

I set the SPEED_UNIT to _001Hz but the feedback from the SPD_GetAvrgMecSpeedUnit procedure still seems to be in units rounded to 6.

For example I can read 3059 and 3064 but nothing in between. I'm running a 6 pole-pair motor at nominally 30.5Hz and my requirement for speed variation is <2us p-p jitter. I'm finding it quite challenging ;)

I'm using a STM32G431 48-pin device with a STSPIN233 using 5V on a custom board. My start current peak is about 700mA and my run current is typically 35mA peak.

For my speed feedback in procedure STC_CalcTorqueReference is SPD_GetAvrgMecSpeedUnit the correct procedure to use to get measured speed?

Also, I can not find the source code that SPD_GetAvrgMecSpeedUnit uses to calculate the average, I think it is procedure STO_PLL_CalcAvrgMecSpeedUnit. Is that available?

Thank you for consideration of my problem. All suggestions welcomed.