signal with High-z value can't update in process block!
I design a system that contain SDRAM and spartan6 FPGA. I wrote SDRAM-Controller code for handle the SDRAM. In my code the defualt value of the SDRAM_DQ is High-z. My problem is that i send my data to SDRAM and recieved it but the received value is always 0xFF...FF.
the code is :
SDRAM_DQ <= (others => 'z');
case state_reg is
when wr0 =>
SDRAM_DQ <= Data_in;
data_out <= SDRAM_DQ;
seems the SDRAM_DQ signal wouldn't update and always has High-z value.