Pin layout stm32:

PA5 / D13: SPI clock.
PA7 / D11: SPI data MOSI.
PA9 / D8: SPI cs.

PB4 / D5: button 1.
PB5 / D4: button 2.
PB6 / D10: button 3.
PB8 / D15: button 4.


Pin layour FPGA:
JB 7: SPI clock.
JB 8: SPI data.
JB 9: SPI cs.