I'm just starting to learn microblaze and xps and I have a problem with xps_spi core v 1.00. I made some simle design on my Spartan 3e board with this core but SS signal is constantly low. It looks that after I call XSpi_Transfer function device remains busy. The transfer looks ok just after reset (during first while loop), I can see ss signal going from high to low, sck pulses and correct data at the output. Could you please give me some suggestion where can be a problem?