CCS/TMS320F28069M: Instaspin-focto implement the servo motor control with a absolute encoder

Tool/software: Code Composer Studio

Now I want to implement the servo motor control using the Instaspin-foc.Obviously，the FAST encdoer can not work well.

we need an Incremental encoder or an absolute encoder to measure the Electrical angle.

Now I select an absolute encoder which is based on Biss protocol.

I use the TMS320F 28069M and a FPGA implement the servo motor control.

the FPGA read the absolute encoder value and sent the data to the 28069 via SPI bus.

Now I have some question and this scheme.

1.whether the 28069 and fpga scheme is reasonable？

2.I do not konw how to use the abssolute encoder offer the Electrical angle instead of FAST software encoder.

// generate the motor electrical angle
angle_pu = EST_getAngle_pu(obj->estHandle);

3.the 28069 read the electrical angle from the fpga via spi.

whether the 28069 read program can use the spi interrupt ?

how to add the spi read program into the instaspin-foc?

Thanks