I was trying to set up communication with an LCD, but for some reason i can't set any differential capable pins to LVDS, only LVDS_e_3R. The error during compilation is: "Error (169218): I/O standard LVDS on output or bidirectional pin <PIN> is not supported by the device at location 38 (PAD_45) -- only input pins of this I/O standard are allowed at this location". I can't even find any datasheet thas specifies, which pins are input or outputs.
This might be due to several reason. Firstly, do you assign LVDS I/O standard on the pin? Secondly, if you are using bidirectional backplane, maybe you need to use BLVDS instead of this.
https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/hb/cyclone-iv/cyclone4-hand... (Page 128). Finally, are you assigning LVDS on 2.5V I/O Bank?